We use to build similar setups back maybe 40 years ago for testing different things. The constant vacuum source setup can be used for multiple things. Ummm, maybe the only thing I personally would add would be another valve on your red line are vacuum source so you can close it and do a count down after the desired vacuum is acquired. This release's the constant vacuum and can give you a finer reading even though you may not want to test that far. But having the other valve does allow for testing other things that may require a more definite leak test. But that is just my opinion and how some of us use to do it way back. We built multiple different plates etc. for testing different ways. It is good to see someone like you to build your setup. SO many people now days can't figure out anything past a computer are diagnostic screen.
Thx for watching, commenting, & the kinds words. I like ur idea regarding the additional ball valve. In fact, I’ve seen something similar on a hand vacuum tester. However, I’m not sure how to quantify if the valve seat is good or not based on the time it takes to lose vacuum.
@@RelentlessRacingAJ As a starting point, Measure each combustion chamber are single valve are whatever checking. Write down each and try and make all as good as best best one. You will want them natural and clean, do not use any grease as some so mechanics have shown on videos, that defeats the point when trying to get the best seal possible. Plus a vacuum gauge and a tach together can diagnose most anything even the fanciest scanners and equipment can do. If you know what your doing are willing to learn.
excellent tool and video! much more cost effective than buying the whole tool from goodson! and the electric pump could have lots of other uses like getting bubbles out when pouring urethane etc. im working on my own and looking to make an adapter that covers the combustion chamber, so can check all 4 valves at once as well as potentially seeing potential cracks in a head if the valves seal on the outer ports but the chamber itself is not!
I learned something new today, I always use a leak down tester or compression gauge after a engine build which is like putting to cart before the donkey. thanks for the interesting information!
exactly why I made the tool... it's not the end all be all, but it serves a as quick check so I don't waste my time installing the head and whole motor in the car and find out there is an issue. Glad you liked the vid. Pls subscribe. Thx AJ
I have tested my head with vacum but using manual hand pump, is more cheap and you can see easy enhough if the head is good or not. mine got to 25/26 on manual pump.
Good info here, i was doing some diy work on my subaru heads and used the water and air method. It kept failing . I needed to work late and poked around also building a tool . I made mine from an old refridgerator compressor an automotive vacuum gauge a plastic sheet and an oring seal from an old oil filter(junk i had at my disposal) it worked flawlessly. Since the minimum is 22 i passed. It is good also for a quiet setup as the refridgerator compressor has a vacuum and makes very little noise.
I recently duplicated your rig using a 1 Stage 1.5 CFM A/C vac pump with a 0.020" diameter Orfice Restriction fitting placed on the pump suction fitting....I also Added a vacuum In-line Ball cut--off valve between the Orfice Restriction & the Head Port Pad....These additional components let's me measure Significantly Large vac Reading Differences between known Measured valve seat Concentricity measuments of near perfect 0.0005", 0.002" & 0.006" valve seat runout with vac gauge showing Incremental Hg reading differences....The Vacuum shut-off valve closed shows Large vac leak-down rate timings....
I did a valve job and got 3 cylinders ports or whatever maxed out and the 4th one has 25 hg vac. That 4th port valve was super pitted on the intake. MY exhaust valves are perfect
Nice. That’s why I don’t do valve jobs. I figure the machine is much more accurate than me. Also, I only use this tool as a quick check before installing a new head w a fresh valve job.
Awesome video! Great info which I plan to follow. Do you know would I be able to test valves with a single stage 3cfm vacuum pump as that is all I can find locally? Not any 2 stage pumps Thanks
I don't understand why everyone is saying that this test doesn't take into account valve guide/stem/seal leakage. It absolutely DOES. If the head of the valve is sealing one end of the port, and the other end of the port is sealed by the test adapter, it doesn't matter whether there even IS a stem seal or large clearance on the stem. Both ends of the port are sealed during the test. There is no place for the vacuum to leak in that case, other than the valve seat, or the seal on the vacuum tester to the port.
You need to shut off the vacuum and see how long the vacuum holds, A large vacuum pump will pull that vacuum with a poorly seated valve. Another method is to put a bubble glass in the vacuum line to actually see air flow.
Thx for watching and commenting. Agreed… this was discussed already. I have a Goodson hand pump and they had some numbers on the instructions. However, it is unclear how to quantify the correct amount of time for a hood valve seat to hold vacuum. Do you have any suggestions?
It is a very useful tool. I even modified the tool w another ball valve which shuts off the vacuum source. B4 and after lapping valves I measure how long the suction plate stays adhered once the vacuum source is cut off. It tells me how much better the valve seat is sealing as a result of lapping.
@RelentlessRacingAJ I, too, put a tiny ball valve in line to time leak down. Your numbers on good sealing are good numbers to go by and if you get more inches of mercury, that's even better. I think my sealing numbers were closer to 28 in/hg and that was without valve springs on. After those valves smack the seat a few hundred times, they will be set for good. I know I have a good feeling about how the valves sealed in my 4G63 head that I just put on the shortblock yesterday. Good info for everyone! 👍
@@martywilsonwilsonenginesho7940nice... I have been using this tool to evaluate used motors. Usually allows me to get a deal on the motor. I've noticed bent valves won't hold any vacuum. Also, if the valve seat isn't perfect or has corrosion or debris (carbon build up) it at least will hold some vacuum (at least 10 in-Hg). I had a port not hold any vacuum, but fortunately it was large debris between the valve and seat. Some vacuum is my indicator I may have a shot at lapping the valves and saving myself from taking the head to the head rebuilder for a full valve job/replacement. However, if it is a race motor I always rebuild the head and replace the valves and all the other crap anyways. Thx for watching and commenting
Thx for watching and commenting. Remember this is a quick check and u still need to verify w a leak down test. Pls subscribe for more automotive content. Thx again AJ
Very informative, well made video. How does the test described here differ in diagnostic capabilities compared to a water test with pressurized air through the ports. I tested a used head I purchased and out of the 20 valves only two of he exhaust valves show bubbles with the water/air test. Would this method be a more reliable way of telling if there is a valve leak? Thank you
Thx for watching and commenting. Pls subscribe. I’ve found using liquid (I use alcohol) and air pressure thru the ports is ineffective bc with enough air pressure, it can overcome the spring pressure and open the valve.
Good question. B4 I made this contraption, I purchased a hand actuated vacuum from Goodson and couldn’t get a consistent reading bc the suction pad and ports only hold vacuum for so long. Recall, the port is not completely sealed. It leaks thru the valve guide, valve seal, and valve seat (hopefully your machine shop did a good job and the valve seat seals well). Thus, to get a consistent reading I built this contraption to mimic what my machine shop uses to quickly check their heads after final assembly. Don’t forget to subscribe bc I have a lot more content coming soon.
@@RelentlessRacingAJ Thanks for the response! I was asking out of curiosity as I made my own the other day and I've been pulling the vacuum from the head side and if I use a light smear of lithium grease I can turn the pump off and it holds the vac at like - 30inhg for like 20 secs and slowly drops down. Which to me is plenty good of a seal. I figure the piston is going to build pressure and detonate way quicker than the valve can leak down.
@@mgakowski ah... my Goodson hand pump kit came w some light oil for that same reason. I’ve used mine to the head side too, but I prefer checking the port side so I know if it’s the INT or EXH side is leaking. What is CFM rating on your vacuum pump?
Is it possible to use a smaller pump? That pump’s a little pricey so was wanting to get a smaller less expensive one that would do the job. Thoughts, suggestions?
Based on the pass or fail criteria from the gauge at port flow, u need to use the same size pump they use. I haven’t verified that pump size yet. Assuming the pump i chose is correct, using a smaller pump will give u erroneous results
Hi i took my head cylinder for suction test to 2 shops.they both said the test was ok.i put water with detergent on the valves and blow is compressor; some valve were bubbling badly.which sould i follow?.
@@clementmakamo4557 sorry I missed this comment. The vacuum test is not the best all and all test. The real test is a leak down test, but the head must be on the motor for a leak down test. Also, blowing compressed air into the port is not a valid test bc the air pressure and push the valve open. One adtl which I discovered after I made this video is what I call a drop test. I use the same method to apply vacuum to the port, but I added a procedure where I turn off the vacuum source and time how long it takes the suction plate to fall off. Good valve seat seals allow the suction plate to stay attached for about a minute. Hope this helps. -AJ
Is the health of the valve guids and valve seals taken into consideration of your testing? Because they are going to affect how much vacuum is held a great deal.
I believe one has to use some common sense here. The tool merely tells u there is some sort of leak (and how much of leak) and it’s up to the user to figure out where that leak is. I created this tool as a quick check for a new rebuilt head bc I didn’t want to assume the head is good after the rebuild. Also, I’ve wasted my time bc I assumed a rebuilt head was good. It is definitely not the be all end all, but again it’s merely a quick check. A leak can come from a cracked head, valve seal, valve seat, or valve guide. This tool can figure out if it is a valve seat bc it can vacuum the bottom of the head w a larger adapter.
I am not familiar w diesel engines enough (despite having a Cummins as a tow rig) to able to answer your question. However, I do know the cylinder pressures are much higher in a diesel. I’d suggest consulting w a head shop that specializes in diesel head work. Thx for watching and commenting
I had a shop do my engine, lower end work and head work. He did it all. And when he was done i picked it up and the only thing i had to do was put the head on. At some point i watched a youtube video about a guy who checked his valves with water and compressed air. Blowing air in the ports revealed bubbles in the burningchamber. So before i mounted the head back on i did the same test. Some valves let trough some air and i was quite pissed. All that work costed me a lot of money. So i went back with the head. The guy at the shop showed me his test with the vacuum gauge. And guess what......, all valvles seated good. Now the engine is build back together and when im done with the rest of the car i can go to a dyno-shop to set the new ecu. it is now running on a base map. Sometimes i hear a small backfire, and im hoping its because of the basemapping. Or a small vacuum leak. Really hope the valves are seating as they should.
With the pump on it would have to be a leak so bad that the pump couldn't keep up, which is not likely. A real test would be to isolate the pump after vacuum is applied then wait to see if vacuum drops.
Thx for watching and commenting. I learned of this method from my head shop… the only difference is their vacuum pump was part of their head machine. In my experience, when the valve seat leaks (as a result of a bent valve or a bad valve seat) the gauge will not meet the minimum 22 inches of mercury. The method you mentioned does work, but the question is how does one quantify the valve seat is good or not… is 10 seconds for the vacuum to drop off or 15 seconds. Also, keep in mind the port won’t hold vacuum bc the of the imperfections in the valve seat and valve seal. Note, this was discuss in earlier comments. Thx again, AJ
@@RelentlessRacingAJ with the pump on and poorly sealing valves you will almost always attain a lower vacuum reading than other cylinders.. this tool makes it pretty easy to check that the valves pull a consistent and even amount of vacuum.. I have used a similar pnuematic tool and sometimes found a 4" difference in vacuum can be remedied by another hand lap of the offending valves... your better off making sure everything is close before the engine is running
The intake and exhaust port won’t hold perfect vacuum which is why I’m looking for a minimum vacuum number (because it isn’t possible). The leak can be from an out of spec valve guide (meaning the valve guide hole is too big or worn), an old valve seal, or the valve seat. This tool serves as a quick check after a head has been rebuilt. If u get a number below the minimum, then it’s on you to figure out what isn’t sealing properly. I hope this answers your question
Let’s assume you reverse the process & fill the port with positive pressure. The positive pressure can easily over power the spring pressure holding the valve closed.
@@RelentlessRacingAJ it depends on the size of u'r cylinder and the volume from bottom dead center to top dead center, then you can determine how much pressure your going to put in the head
@@siegfredvisitacion736 I am familiar w leak down testing and that’s typically down w the piston at TDC. I’ve never considered the method u r proposing. Pls explain more
I love the idea of making this tool at home. But I think there might be an easier way of doing it. An R134 A/C manifold set already includes the gauge, and the fittings to connect to the A/C Vacuum Pump. You will need the valve test plate and an adapter to connect it to the low side (blue hose) fitting.
Yeah I thought about doing it that way, but didn’t want to destroy my gauge set. Also, when I priced out the gauge sets they were more expensive compared to my contraption. Thx for watching and commenting. Pls subscribe for more automotive content 👊
@v8powerv8jim the vacuum pump is always on bc the ports won’t hold vacuum wo the pump on bc there is a slight leak thru the valve guide and valve seal.
@@RelentlessRacingAJ I’m using a hand operated vacuum pump, I can get all the valves to around 22 inches of vacuum but the readings slowly go down if I stop pumping, so all good right?
@@v8powerv8jim I made the mistake of buying a hand pump, too. The hand pump can’t maintain enough of a constant vacuum for you to determine if your valve guides, seals, or seats are sealing well enough. That’s y I built this tool. Take ur head to a head shop and have it tested. Good luck
So, it looks to me that you’re supplying a consistent negative pressure to your test area? Wouldn’t you want to see how much negative pressure the runner or chamber can hold on its own?
AJ JAQUIAS well, for one, it’s pretty hard to know how much vacuum is leaking through the guide vs seat. I’ve always used a plate on the chamber. Sioux makes a pneumatic vacuum plate gun (very expensive) I used to be cylinder head specialist years ago. I would achieve a positive seal on chambers. I am now working on a 454 of my own, and have achieved slow leakage after a 3 angle which I’ve done. I started to look on line to see if there was a certain amount of leak down which is acceptable. I used to hand lap slow leaking valves after 3 angle if necessary to achieve 0 leak down, but at this point I’m ready to get engine put back together and assume that with the slight amount of leak down, they will seat the rest of the way.
@@tonysabatino4725 well, I originally bought the Goodson hand vacuum pump & found I couldn’t achieve consistent data. Also, the purpose of this was to double check the head shop after a head rebuild so I don’t put the whole motor together and install it to find out on the dyno I have a leaking valve seat. It’s merely a quick check and if there’s an issue I know I have to take apart the suspect valve and perform an inspection of the seat and valve
Were the spring installed when you did this? I have a problem where i had seats done and the valves still leak. i believe the issue is weak springs and this would help me narrow down the issue.
Barry Spurlock yes they springs were installed. Any time there is a leak, the port will not hold vacuum. Also, a leak is generally at the seat and caused by a bad valve job or a bent valve.
Nice video & you've got the correct concept, but your rig needs a few tweaks to be functionality helpful....Your 3 Cfm pump is way too large & grossly Over-pumping the typical 200 cc (0.01 Cu.Ft.) cyl head port making your tester Very Insensitive to all but extreme leaking valves...Use a Smaller 0.2 Cfm pump or put a small 0.020" diameter restriction Orfice directly on the large pump...You Must also add a vacuum isolation/shut off ball valve to the vac test pad hose line to enable the critical "pump off/vacuum hold" timed test where > 10 sec per 10 lost Psi is required for test pass....
Ahhh. Finally someone w numbers. May I ask where your numbers come from? Also, I’ve added another ball valve so I can shut off the vacuum and see how long the port will hold vacuum.
Also,....Even the cheapest 1 stage AC vacuum pump Will pull 29" Hg vacuum into a perfect airtight plug--off But I notice commercially built cylinder head machines (like Serdi, etc) valve vacuum test pump Only pulls to 22" Hg on a 0 --30" Hg vac gauge.....I'm fairly sure their pump is much smaller than a typical HVAC vac pump you're using & may Not even be a Rotary Vane type !! Could be a much simpler Piston/Diaphragm vac pump that can only pull 22" Hg vacuum !! The "Timed" Vacuum Hold test seems to be the "Real" important Valve to Seat Sealing performance Indicator type test...
@@tomstrum6259 sounds interesting, but where are you referencing all these numbers? I’d like to research what you are stating more. Does Serdi post the specs on their pumps?
Well,...not being in the "trade",...my best info Reference is the "Cummings N14 Cyl Head Vacuum Testing Valve Seating using the ST--1257 Vacuum Tester".....That procedure requires pulling 20" --25" Hg vac on the pump with a Timed pump off/Leak-Down rate from 18" Hg to 8" Hg Greater than 10 seconds time....Another reliable Reference is the "VACUTEST 116 Electric Vacuum Tester" that pump is Spec'd at 11.6 L/minute (0.4 CFM) at
There are tools like this for sale but they are quite expensive which is why I made this one. With respect, to using this as a leak down tester I don’t think it will work. It would easier and cheaper to purchase a quality leak down tester. Thx for watching and commenting on my video. Pls subscribe for more automotive content. 👊
Yes your pulling vacuum, but most pumps for a/c are designed to pull 30lbs , the real test is after pulling vacuum shut the pump off , you should hold the vacuum. best is to have a shut off valve between pump & head. reason for that is you will pull oil out of pump when shut off without a shut off valve. every head i do must hold 30 pounds vacuum with pump off. if it don't hold vacuum with the pump off you have a leak. fill the ports with laquer thinner & blow air around valve you will see were it is leaking. think about it just because you are pulling vacuum don't mean they are not leaking. holding vacuum is the real test
@@ScottGreen-r3r I agree w you and have since changed my setup to turn off the vacuum. Again, this is merely a quick check and not the be all end all for a valve seat test. It won’t hold vacuum forever because it is not a perfectly sealed orifice. So, the question begs how long should it hold vacuum? I have some valves which hold over a minute before the pad falls off after turning off the vacuum. So, again, what’s the criteria… how long should it hold the pad there and does 20 more secs equal more HP? How much HP for x amount of seconds? Appreciate your comment and you watching.
I’ve visited Port Flow about 6,000 times and his valve cutting machine has a vacuum gauge attached to it. His gauge not only has inHg on it, but also an area colored in green indicating an acceptable valve seat seal and that’s where the .7 bar threshold came from.
@@RelentlessRacingAJ How does his vacuum pump compare to yours though? A higher volume pump will create more vacuum for a given valve to valve seat gap. A pressure leakdown tester with a known orifice size would be a more reproducible method I think
@@paulkube5338 I’m not sure if I agree... vacuum is vacuum - meaning one can only achieve so much vacuum (at sea level 29.92 in Hg). Thus, using a larger vacuum pump doesn’t mean it will pull more vacuum, it means it will evacuate the air faster for a given volume. Additionally, using a leak down pressure tester works well when the motor is assembled bc it applies pressure to bottom of the valve in the combustion chamber and then the operator determines the leakage point (valve seats, rings, or head gasket). Testing the ports w vacuum is an industry standard as opposed to pressure testing the ports. Why? Bc it is very easy to apply enough pressure to overcome the spring pressure on the seats and it is an easy test when the cylinder head is off the block. Hope this helps.
@@RelentlessRacingAJ In your setup, the pressure on the front (combustion chamber side) of the valves is constant atmospheric pressure. On a particular cylinder, the seat gap causing the valves not to seal perfectly is a constant size. So the rate of flow of air through the gap is a function of air pressure at the back (manifold side) of the valves only. But what is that pressure? At equilibrium it's the pressure that makes the flow through the valves equal the flow into the vacuum pump. So you can see that a high-flow pump can create a lower manifold pressure (better vacuum) than a low-flow pump for a given valve seat gap.
@@paulkube5338 that’s a good point. I suppose the way I’m thinking about it is for a perfectly sealed system. So, u r correct... in a leaking system flow rate will have an effect on the vacuum level. I’ll have to ask Tom which machine he has and verify the flow rate of his pump. In any case, I created this as a quick check for a cylinder head b4 it is installed on a block. I installed one of my motors multiple times w a leaking valve seat and it was extremely time consuming. After the ordeal, I tried different methods to test the seats and this one proved to b the most reliable. The tests I tried included pressure into the ports (the pressure exceeded the spring force), alcohol in the top of the combustion chamber, alcohol in the top of the combustion chamber w pressure in the ports, and cold leak down test at 100 psi (air came thru known good seats). Pls share if u have a better method.
Thx for watching and commenting. Agreed, but what is the acceptable decay rate? Note, we have discussed this in the comments already and no one seems to know what the acceptable decay rate is. Perhaps, u can be the savior. thx again, AJ
@@RelentlessRacingAJ decay rate would depend on temperature since most valve jobs consist of of having the valves cut 0.5° shallower than the seat so in theory the seal would be ideal at operating temperature. The best measurement I can think of would be using microns and at near perfect vacuum with the head at room temperature as a control. Similar to drawing a deep vacuum on an AC/heat pump system many things influence your decay rate(moisture,ambient temperature, non-condensables, etc). For a street head if it could hold 25-26 inhg for 10 seconds that is probably sealed more than enough to pass a leak down test and therefore have a proper seal for combustion. There really is no way of knowing unless a perfectly sealed head under ideal testing conditions was measured to be used as a control. This is just my opinion do with it what you will just figured I'd throw it out there
@@anjewbagel4755 appreciate the explanation, but again this is only used as a quick check prior to installing a head. You can quickly double check for a bad seat or bent valve.
I used to do that too, but it’s not a good check. A slightly leaking valve seat can still hold a liquid. Also, if the valves hold liquid you don’t really know how good the valve is sealing. This tool tells how good or bad the valve is sealing against the valve seat. Another test is to pull vacuum on the port, remove the vacuum, and time how long the suction plate takes to fall off. I use this to check if lapping the valve improved the seal between the valve and seat.
After having more testing time & Experience with this type of Vacuum Tester, my takeaway is the Highest gauge Hg reading With Running pump Only test Can mask some slightly Leaking valve seats & confuse the Real valve sealing Quality Evaluation...With any pump ( at least capable of 25" Hg vac) the Highest Resolution leak Detection Results Is with pump Off, valve closed & Carefully Timing the Leak-Down Rate....A known High Quantity valve seat Will hold Vacuum with Leak-Down rate of > 10 seconds per Hg" or > 100 seconds per 10 Hg"...
im thinking about adding a check valve to the tool I am making, or have it easily installed right after the port adapter so that with a trigger style vacuum tester you could start a timer as soon as you let off the momentary switch (and hopefully the check valve seals quick enough to not lose any vacuum) of course the vacuum gauge would also need to be port side before the check valve to get a reading.
You're not doing it right. You pull a vacuum then you shut off sustion from the pump and watch to see how long it holds the vacuum. If it doesn't hold it at least 7-10 seconds you don't have a good seal on your valve.
I’ve seen that method as well and I agree w u. Again, I agree w u. However, I am using this as a quick check for detecting a gross leakage in the seat.
@@RelentlessRacingAJ After I posted I realized that the method I mentioned only works by placing the suction on the cylinder side with the springs intalled. It would never work on the port side since you have guides that will cause considerable leakage. I just happen to be doing a valve job on a Cummins 15L ISX at the moment so the procedure fo it was fresh in my mind. I too made a setup for it using almost the identical setup you have. However there is no recess in the cylinder area so applying the suction cap isn't a problem like it would be on your head. Anyway you're right for your application and I was right for mine. If nothing else my post gave us something to ponder.
As mentioned, this is not the end all be all test. I merely created this tester to check if the head shop made a blatant mistake. Also, according to my research and testing, the vacuum pump is not too strong. A port will not hold over 22 in Hg if there is a small leak. If you don’t believe it, get off the keyboard and make a tester and prove it to yourself.
I had doubts about using vaccum......but your methodology was perfect!!!! Great tool...great job!!!
Thx for watching, commenting, and the kind words. Pls subscribe
We use to build similar setups back maybe 40 years ago for testing different things. The constant vacuum source setup can be used for multiple things. Ummm, maybe the only thing I personally would add would be another valve on your red line are vacuum source so you can close it and do a count down after the desired vacuum is acquired. This release's the constant vacuum and can give you a finer reading even though you may not want to test that far. But having the other valve does allow for testing other things that may require a more definite leak test. But that is just my opinion and how some of us use to do it way back. We built multiple different plates etc. for testing different ways. It is good to see someone like you to build your setup. SO many people now days can't figure out anything past a computer are diagnostic screen.
Thx for watching, commenting, & the kinds words. I like ur idea regarding the additional ball valve. In fact, I’ve seen something similar on a hand vacuum tester. However, I’m not sure how to quantify if the valve seat is good or not based on the time it takes to lose vacuum.
@@RelentlessRacingAJ As a starting point, Measure each combustion chamber are single valve are whatever checking. Write down each and try and make all as good as best best one. You will want them natural and clean, do not use any grease as some so mechanics have shown on videos, that defeats the point when trying to get the best seal possible. Plus a vacuum gauge and a tach together can diagnose most anything even the fanciest scanners and equipment can do. If you know what your doing are willing to learn.
@@rickyshuptrine2831 next head I check I’ll try it. Thx again, AJ
Brilliant video . Your dam right about having to check other peoples work also .
I appreciate the kind words. Pls subscribe bc there’s more automotive content coming soon.
excellent tool and video! much more cost effective than buying the whole tool from goodson! and the electric pump could have lots of other uses like getting bubbles out when pouring urethane etc. im working on my own and looking to make an adapter that covers the combustion chamber, so can check all 4 valves at once as well as potentially seeing potential cracks in a head if the valves seal on the outer ports but the chamber itself is not!
I learned something new today, I always use a leak down tester or compression gauge after a engine build which is like putting to cart before the donkey. thanks for the interesting information!
exactly why I made the tool... it's not the end all be all, but it serves a as quick check so I don't waste my time installing the head and whole motor in the car and find out there is an issue. Glad you liked the vid. Pls subscribe. Thx AJ
I have tested my head with vacum but using manual hand pump, is more cheap and you can see easy enhough if the head is good or not. mine got to 25/26 on manual pump.
Good info here, i was doing some diy work on my subaru heads and used the water and air method. It kept failing . I needed to work late and poked around also building a tool . I made mine from an old refridgerator compressor an automotive vacuum gauge a plastic sheet and an oring seal from an old oil filter(junk i had at my disposal) it worked flawlessly. Since the minimum is 22 i passed. It is good also for a quiet setup as the refridgerator compressor has a vacuum and makes very little noise.
Nice. Like I wrote b4, it’s not the be all end all, but merely a quick check. pls subscribe. Thx AJ
I recently duplicated your rig using a 1 Stage 1.5 CFM A/C vac pump with a 0.020" diameter Orfice Restriction fitting placed on the pump suction fitting....I also Added a vacuum In-line Ball cut--off valve between the Orfice Restriction & the Head Port Pad....These additional components let's me measure Significantly Large vac Reading Differences between known Measured valve seat Concentricity measuments of near perfect 0.0005", 0.002" & 0.006" valve seat runout with vac gauge showing Incremental Hg reading differences....The Vacuum shut-off valve closed shows Large vac leak-down rate timings....
I did a valve job and got 3 cylinders ports or whatever maxed out and the 4th one has 25 hg vac. That 4th port valve was super pitted on the intake. MY exhaust valves are perfect
Nice. That’s why I don’t do valve jobs. I figure the machine is much more accurate than me. Also, I only use this tool as a quick check before installing a new head w a fresh valve job.
Awesome video!
Great info which I plan to follow.
Do you know would I be able to test valves with a single stage 3cfm vacuum pump as that is all I can find locally?
Not any 2 stage pumps
Thanks
yes it will work
I don't understand why everyone is saying that this test doesn't take into account valve guide/stem/seal leakage. It absolutely DOES. If the head of the valve is sealing one end of the port, and the other end of the port is sealed by the test adapter, it doesn't matter whether there even IS a stem seal or large clearance on the stem. Both ends of the port are sealed during the test. There is no place for the vacuum to leak in that case, other than the valve seat, or the seal on the vacuum tester to the port.
You need to shut off the vacuum and see how long the vacuum holds,
A large vacuum pump will pull that vacuum with a poorly seated valve.
Another method is to put a bubble glass in the vacuum line to actually see air flow.
Thx for watching and commenting. Agreed… this was discussed already. I have a Goodson hand pump and they had some numbers on the instructions. However, it is unclear how to quantify the correct amount of time for a hood valve seat to hold vacuum. Do you have any suggestions?
I made a tool almost identical to yours and they DO work really well and gives you Peace of Mind! ❤ Good video, better than mine, lol.
It is a very useful tool. I even modified the tool w another ball valve which shuts off the vacuum source. B4 and after lapping valves I measure how long the suction plate stays adhered once the vacuum source is cut off. It tells me how much better the valve seat is sealing as a result of lapping.
@RelentlessRacingAJ I, too, put a tiny ball valve in line to time leak down. Your numbers on good sealing are good numbers to go by and if you get more inches of mercury, that's even better. I think my sealing numbers were closer to 28 in/hg and that was without valve springs on. After those valves smack the seat a few hundred times, they will be set for good. I know I have a good feeling about how the valves sealed in my 4G63 head that I just put on the shortblock yesterday. Good info for everyone! 👍
@@martywilsonwilsonenginesho7940nice... I have been using this tool to evaluate used motors. Usually allows me to get a deal on the motor. I've noticed bent valves won't hold any vacuum. Also, if the valve seat isn't perfect or has corrosion or debris (carbon build up) it at least will hold some vacuum (at least 10 in-Hg). I had a port not hold any vacuum, but fortunately it was large debris between the valve and seat. Some vacuum is my indicator I may have a shot at lapping the valves and saving myself from taking the head to the head rebuilder for a full valve job/replacement. However, if it is a race motor I always rebuild the head and replace the valves and all the other crap anyways. Thx for watching and commenting
excellent teacher , all I can sa;y , thanks a million .
Thx for watching and commenting. Remember this is a quick check and u still need to verify w a leak down test. Pls subscribe for more automotive content. Thx again AJ
Very informative, well made video. How does the test described here differ in diagnostic capabilities compared to a water test with pressurized air through the ports. I tested a used head I purchased and out of the 20 valves only two of he exhaust valves show bubbles with the water/air test. Would this method be a more reliable way of telling if there is a valve leak? Thank you
Thx for watching and commenting. Pls subscribe. I’ve found using liquid (I use alcohol) and air pressure thru the ports is ineffective bc with enough air pressure, it can overcome the spring pressure and open the valve.
@@RelentlessRacingAJ Thank you.
Excellent work! Thank you for sharing.
Thx for watching and commenting. Pls subscribe. Thx AJ
Well spoken my dude
Thank you. Pls subscribe. -AJ
How do valves go holding vaccum when you turn off the vac pump or close off the suction source? Do they hold that vacuum or how quickly does it drop?
Good question. B4 I made this contraption, I purchased a hand actuated vacuum from Goodson and couldn’t get a consistent reading bc the suction pad and ports only hold vacuum for so long. Recall, the port is not completely sealed. It leaks thru the valve guide, valve seal, and valve seat (hopefully your machine shop did a good job and the valve seat seals well). Thus, to get a consistent reading I built this contraption to mimic what my machine shop uses to quickly check their heads after final assembly. Don’t forget to subscribe bc I have a lot more content coming soon.
@@RelentlessRacingAJ Thanks for the response! I was asking out of curiosity as I made my own the other day and I've been pulling the vacuum from the head side and if I use a light smear of lithium grease I can turn the pump off and it holds the vac at like - 30inhg for like 20 secs and slowly drops down. Which to me is plenty good of a seal. I figure the piston is going to build pressure and detonate way quicker than the valve can leak down.
@@mgakowski ah... my Goodson hand pump kit came w some light oil for that same reason. I’ve used mine to the head side too, but I prefer checking the port side so I know if it’s the INT or EXH side is leaking. What is CFM rating on your vacuum pump?
Is it possible to use a smaller pump? That pump’s a little pricey so was wanting to get a smaller less expensive one that would do the job. Thoughts, suggestions?
Based on the pass or fail criteria from the gauge at port flow, u need to use the same size pump they use. I haven’t verified that pump size yet. Assuming the pump i chose is correct, using a smaller pump will give u erroneous results
Hi i took my head cylinder for suction test to 2 shops.they both said the test was ok.i put water with detergent on the valves and blow is compressor; some valve were bubbling badly.which sould i follow?.
@@clementmakamo4557 sorry I missed this comment. The vacuum test is not the best all and all test. The real test is a leak down test, but the head must be on the motor for a leak down test. Also, blowing compressed air into the port is not a valid test bc the air pressure and push the valve open. One adtl which I discovered after I made this video is what I call a drop test. I use the same method to apply vacuum to the port, but I added a procedure where I turn off the vacuum source and time how long it takes the suction plate to fall off. Good valve seat seals allow the suction plate to stay attached for about a minute. Hope this helps. -AJ
Is the health of the valve guids and valve seals taken into consideration of your testing? Because they are going to affect how much vacuum is held a great deal.
I believe one has to use some common sense here. The tool merely tells u there is some sort of leak (and how much of leak) and it’s up to the user to figure out where that leak is. I created this tool as a quick check for a new rebuilt head bc I didn’t want to assume the head is good after the rebuild. Also, I’ve wasted my time bc I assumed a rebuilt head was good. It is definitely not the be all end all, but again it’s merely a quick check. A leak can come from a cracked head, valve seal, valve seat, or valve guide. This tool can figure out if it is a valve seat bc it can vacuum the bottom of the head w a larger adapter.
Hello are these values -0.7bar just for petrol engines or for diesel as well? Thank you for the great content
I am not familiar w diesel engines enough (despite having a Cummins as a tow rig) to able to answer your question. However, I do know the cylinder pressures are much higher in a diesel. I’d suggest consulting w a head shop that specializes in diesel head work. Thx for watching and commenting
I had a shop do my engine, lower end work and head work.
He did it all. And when he was done i picked it up and the only thing i had to do was put the head on.
At some point i watched a youtube video about a guy who checked his valves with water and compressed air. Blowing air in the ports revealed bubbles in the burningchamber.
So before i mounted the head back on i did the same test.
Some valves let trough some air and i was quite pissed. All that work costed me a lot of money. So i went back with the head.
The guy at the shop showed me his test with the vacuum gauge. And guess what......, all valvles seated good.
Now the engine is build back together and when im done with the rest of the car i can go to a dyno-shop to set the new ecu.
it is now running on a base map. Sometimes i hear a small backfire, and im hoping its because of the basemapping. Or a small vacuum leak.
Really hope the valves are seating as they should.
I created this tool as a quick check and it’s not the end all be all, but I serves its purpose. Good luck w ur cylinder head. Pls subscribe AJ
With the pump on it would have to be a leak so bad that the pump couldn't keep up, which is not likely. A real test would be to isolate the pump after vacuum is applied then wait to see if vacuum drops.
Thx for watching and commenting. I learned of this method from my head shop… the only difference is their vacuum pump was part of their head machine. In my experience, when the valve seat leaks (as a result of a bent valve or a bad valve seat) the gauge will not meet the minimum 22 inches of mercury. The method you mentioned does work, but the question is how does one quantify the valve seat is good or not… is 10 seconds for the vacuum to drop off or 15 seconds. Also, keep in mind the port won’t hold vacuum bc the of the imperfections in the valve seat and valve seal. Note, this was discuss in earlier comments. Thx again, AJ
@@RelentlessRacingAJ with the pump on and poorly sealing valves you will almost always attain a lower vacuum reading than other cylinders.. this tool makes it pretty easy to check that the valves pull a consistent and even amount of vacuum.. I have used a similar pnuematic tool and sometimes found a 4" difference in vacuum can be remedied by another hand lap of the offending valves... your better off making sure everything is close before the engine is running
Thanks for a great video
Welcome. Thx for the kind words. It has been very helpful in verifying a heads valve and seat condition. Pls subscribe. Thx AJ
If you check on the in.and ex. Ports what about the clearance in the valve guide
How does that hold a vacuum?
The intake and exhaust port won’t hold perfect vacuum which is why I’m looking for a minimum vacuum number (because it isn’t possible). The leak can be from an out of spec valve guide (meaning the valve guide hole is too big or worn), an old valve seal, or the valve seat. This tool serves as a quick check after a head has been rebuilt. If u get a number below the minimum, then it’s on you to figure out what isn’t sealing properly. I hope this answers your question
What if u'll going to reverse the process put a pressure on the head and test for any leaks
Let’s assume you reverse the process & fill the port with positive pressure. The positive pressure can easily over power the spring pressure holding the valve closed.
@@RelentlessRacingAJ it depends on the size of u'r cylinder and the volume from bottom dead center to top dead center, then you can determine how much pressure your going to put in the head
@@siegfredvisitacion736 I am familiar w leak down testing and that’s typically down w the piston at TDC. I’ve never considered the method u r proposing. Pls explain more
Great job how to make one of that tester
Thank you for watching and commenting. Pls subscribe.
Can you list the brands for those plates please? I would appreciate thanks
Thanks for watching the video. Pls note all the parts used are listed in the video and source is included, too.
I love the idea of making this tool at home. But I think there might be an easier way of doing it. An R134 A/C manifold set already includes the gauge, and the fittings to connect to the A/C Vacuum Pump. You will need the valve test plate and an adapter to connect it to the low side (blue hose) fitting.
Yeah I thought about doing it that way, but didn’t want to destroy my gauge set. Also, when I priced out the gauge sets they were more expensive compared to my contraption. Thx for watching and commenting. Pls subscribe for more automotive content 👊
Do you check the valves hold the vacuum with the pump also switched off?
@v8powerv8jim the vacuum pump is always on bc the ports won’t hold vacuum wo the pump on bc there is a slight leak thru the valve guide and valve seal.
@@RelentlessRacingAJ I’m using a hand operated vacuum pump, I can get all the valves to around 22 inches of vacuum but the readings slowly go down if I stop pumping, so all good right?
@@v8powerv8jim I made the mistake of buying a hand pump, too. The hand pump can’t maintain enough of a constant vacuum for you to determine if your valve guides, seals, or seats are sealing well enough. That’s y I built this tool. Take ur head to a head shop and have it tested. Good luck
So, it looks to me that you’re supplying a consistent negative pressure to your test area? Wouldn’t you want to see how much negative pressure the runner or chamber can hold on its own?
Pls elaborate why you want to know how much negative pressure the chamber holds? Also, how would u test just the chamber ?
AJ JAQUIAS well, for one, it’s pretty hard to know how much vacuum is leaking through the guide vs seat. I’ve always used a plate on the chamber. Sioux makes a pneumatic vacuum plate gun (very expensive) I used to be cylinder head specialist years ago. I would achieve a positive seal on chambers. I am now working on a 454 of my own, and have achieved slow leakage after a 3 angle which I’ve done. I started to look on line to see if there was a certain amount of leak down which is acceptable. I used to hand lap slow leaking valves after 3 angle if necessary to achieve 0 leak down, but at this point I’m ready to get engine put back together and assume that with the slight amount of leak down, they will seat the rest of the way.
@@tonysabatino4725 well, I originally bought the Goodson hand vacuum pump & found I couldn’t achieve consistent data. Also, the purpose of this was to double check the head shop after a head rebuild so I don’t put the whole motor together and install it to find out on the dyno I have a leaking valve seat. It’s merely a quick check and if there’s an issue I know I have to take apart the suspect valve and perform an inspection of the seat and valve
Were the spring installed when you did this? I have a problem where i had seats done and the valves still leak. i believe the issue is weak springs and this would help me narrow down the issue.
Barry Spurlock yes they springs were installed. Any time there is a leak, the port will not hold vacuum. Also, a leak is generally at the seat and caused by a bad valve job or a bent valve.
Nice video & you've got the correct concept, but your rig needs a few tweaks to be functionality helpful....Your 3 Cfm pump is way too large & grossly Over-pumping the typical 200 cc (0.01 Cu.Ft.) cyl head port making your tester Very Insensitive to all but extreme leaking valves...Use a Smaller 0.2 Cfm pump or put a small 0.020" diameter restriction Orfice directly on the large pump...You Must also add a vacuum isolation/shut off ball valve to the vac test pad hose line to enable the critical "pump off/vacuum hold" timed test where > 10 sec per 10 lost Psi is required for test pass....
Ahhh. Finally someone w numbers. May I ask where your numbers come from? Also, I’ve added another ball valve so I can shut off the vacuum and see how long the port will hold vacuum.
Also,....Even the cheapest 1 stage AC vacuum pump Will pull 29" Hg vacuum into a perfect airtight plug--off But I notice commercially built cylinder head machines (like Serdi, etc) valve vacuum test pump Only pulls to 22" Hg on a 0 --30" Hg vac gauge.....I'm fairly sure their pump is much smaller than a typical HVAC vac pump you're using & may Not even be a Rotary Vane type !! Could be a much simpler Piston/Diaphragm vac pump that can only pull 22" Hg vacuum !! The "Timed" Vacuum Hold test seems to be the "Real" important Valve to Seat Sealing performance Indicator type test...
@@tomstrum6259 sounds interesting, but where are you referencing all these numbers? I’d like to research what you are stating more. Does Serdi post the specs on their pumps?
Well,...not being in the "trade",...my best info Reference is the "Cummings N14 Cyl Head Vacuum Testing Valve Seating using the ST--1257 Vacuum Tester".....That procedure requires pulling 20" --25" Hg vac on the pump with a Timed pump off/Leak-Down rate from 18" Hg to 8" Hg Greater than 10 seconds time....Another reliable Reference is the "VACUTEST 116 Electric Vacuum Tester" that pump is Spec'd at 11.6 L/minute (0.4 CFM) at
Continued,....At -- 850 mbar (25" Hg).......
It’s very good tools, you might be able to make it and sale online , is it possible to leak down test with this tool
There are tools like this for sale but they are quite expensive which is why I made this one. With respect, to using this as a leak down tester I don’t think it will work. It would easier and cheaper to purchase a quality leak down tester. Thx for watching and commenting on my video. Pls subscribe for more automotive content. 👊
@@RelentlessRacingAJ I really like what you made
Can you send me parts numbers please
@@bestenginejdm1543 all parts are listed in the video
Yes your pulling vacuum, but most pumps for a/c are designed to pull 30lbs , the real test is after pulling vacuum shut the pump off , you should hold the vacuum. best is to have a shut off valve between pump & head. reason for that is you will pull oil out of pump when shut off without a shut off valve. every head i do must hold 30 pounds vacuum with pump off. if it don't hold vacuum with the pump off you have a leak. fill the ports with laquer thinner & blow air around valve you will see were it is leaking. think about it just because you are pulling vacuum don't mean they are not leaking.
holding vacuum is the real test
@@ScottGreen-r3r I agree w you and have since changed my setup to turn off the vacuum. Again, this is merely a quick check and not the be all end all for a valve seat test. It won’t hold vacuum forever because it is not a perfectly sealed orifice. So, the question begs how long should it hold vacuum? I have some valves which hold over a minute before the pad falls off after turning off the vacuum. So, again, what’s the criteria… how long should it hold the pad there and does 20 more secs equal more HP? How much HP for x amount of seconds? Appreciate your comment and you watching.
Can you help me with a parts list so I can make this tool please.
Every part is listed in the video. Thx for watching and commenting. Pls subscribe. Thx, AJ
Thancks
Very welcome. Pls subscribe bc there’s more automotive content coming 👊
i couldn’t find the vacuum plate ? i search amazon ebay and google only find the whole kit which is 99 dollars
See 3:29. Pls subscribe to my channel... there's more automotive content coming soon
Where did you come up with the 22 in Hg / .7 bar threshold number for determining a good valve seal?
I’ve visited Port Flow about 6,000 times and his valve cutting machine has a vacuum gauge attached to it. His gauge not only has inHg on it, but also an area colored in green indicating an acceptable valve seat seal and that’s where the .7 bar threshold came from.
@@RelentlessRacingAJ How does his vacuum pump compare to yours though? A higher volume pump will create more vacuum for a given valve to valve seat gap. A pressure leakdown tester with a known orifice size would be a more reproducible method I think
@@paulkube5338 I’m not sure if I agree... vacuum is vacuum - meaning one can only achieve so much vacuum (at sea level 29.92 in Hg). Thus, using a larger vacuum pump doesn’t mean it will pull more vacuum, it means it will evacuate the air faster for a given volume. Additionally, using a leak down pressure tester works well when the motor is assembled bc it applies pressure to bottom of the valve in the combustion chamber and then the operator determines the leakage point (valve seats, rings, or head gasket). Testing the ports w vacuum is an industry standard as opposed to pressure testing the ports. Why? Bc it is very easy to apply enough pressure to overcome the spring pressure on the seats and it is an easy test when the cylinder head is off the block. Hope this helps.
@@RelentlessRacingAJ In your setup, the pressure on the front (combustion chamber side) of the valves is constant atmospheric pressure. On a particular cylinder, the seat gap causing the valves not to seal perfectly is a constant size. So the rate of flow of air through the gap is a function of air pressure at the back (manifold side) of the valves only. But what is that pressure? At equilibrium it's the pressure that makes the flow through the valves equal the flow into the vacuum pump. So you can see that a high-flow pump can create a lower manifold pressure (better vacuum) than a low-flow pump for a given valve seat gap.
@@paulkube5338 that’s a good point. I suppose the way I’m thinking about it is for a perfectly sealed system. So, u r correct... in a leaking system flow rate will have an effect on the vacuum level. I’ll have to ask Tom which machine he has and verify the flow rate of his pump. In any case, I created this as a quick check for a cylinder head b4 it is installed on a block. I installed one of my motors multiple times w a leaking valve seat and it was extremely time consuming. After the ordeal, I tried different methods to test the seats and this one proved to b the most reliable. The tests I tried included pressure into the ports (the pressure exceeded the spring force), alcohol in the top of the combustion chamber, alcohol in the top of the combustion chamber w pressure in the ports, and cold leak down test at 100 psi (air came thru known good seats). Pls share if u have a better method.
Tqvm👍
I need to buy this can you make one for me please
Pls email me at shoprelentlessracing@gmail.com
do u have a parts list for this.
Everything u need is in the video 👍
the real test isn't how deep a vacuum can be pulled with a 3CFM pump, the true test is how long it can be held(decay test)
Thx for watching and commenting. Agreed, but what is the acceptable decay rate? Note, we have discussed this in the comments already and no one seems to know what the acceptable decay rate is. Perhaps, u can be the savior. thx again, AJ
@@RelentlessRacingAJ decay rate would depend on temperature since most valve jobs consist of of having the valves cut 0.5° shallower than the seat so in theory the seal would be ideal at operating temperature. The best measurement I can think of would be using microns and at near perfect vacuum with the head at room temperature as a control. Similar to drawing a deep vacuum on an AC/heat pump system many things influence your decay rate(moisture,ambient temperature, non-condensables, etc). For a street head if it could hold 25-26 inhg for 10 seconds that is probably sealed more than enough to pass a leak down test and therefore have a proper seal for combustion. There really is no way of knowing unless a perfectly sealed head under ideal testing conditions was measured to be used as a control. This is just my opinion do with it what you will just figured I'd throw it out there
@@anjewbagel4755 appreciate the explanation, but again this is only used as a quick check prior to installing a head. You can quickly double check for a bad seat or bent valve.
Holle I need your help
Thx for watching and commenting. Pls subscribe. What is your question?
U sale these
Geeeeemz!!
HaterHurter sirG345 lol. I’m assuming u liked this video? Any suggestions for improvement? Any suggestions for content?
@@RelentlessRacingAJ 5star rating in my opinion yes! As for content ... I have few things I want to do myself that concerns me.
Or you could do like machine shops do and use a thin liquid.
I used to do that too, but it’s not a good check. A slightly leaking valve seat can still hold a liquid. Also, if the valves hold liquid you don’t really know how good the valve is sealing. This tool tells how good or bad the valve is sealing against the valve seat. Another test is to pull vacuum on the port, remove the vacuum, and time how long the suction plate takes to fall off. I use this to check if lapping the valve improved the seal between the valve and seat.
After having more testing time & Experience with this type of Vacuum Tester, my takeaway is the Highest gauge Hg reading With Running pump Only test Can mask some slightly Leaking valve seats & confuse the Real valve sealing Quality Evaluation...With any pump ( at least capable of 25" Hg vac) the Highest Resolution leak Detection Results Is with pump Off, valve closed & Carefully Timing the Leak-Down Rate....A known High Quantity valve seat Will hold Vacuum with Leak-Down rate of > 10 seconds per Hg" or > 100 seconds per 10 Hg"...
im thinking about adding a check valve to the tool I am making, or have it easily installed right after the port adapter so that with a trigger style vacuum tester you could start a timer as soon as you let off the momentary switch (and hopefully the check valve seals quick enough to not lose any vacuum) of course the vacuum gauge would also need to be port side before the check valve to get a reading.
You're not doing it right. You pull a vacuum then you shut off sustion from the pump and watch to see how long it holds the vacuum. If it doesn't hold it at least 7-10 seconds you don't have a good seal on your valve.
I’ve seen that method as well and I agree w u. Again, I agree w u. However, I am using this as a quick check for detecting a gross leakage in the seat.
@@RelentlessRacingAJ
After I posted I realized that the method I mentioned only works by placing the suction on the cylinder side with the springs intalled. It would never work on the port side since you have guides that will cause considerable leakage. I just happen to be doing a valve job on a Cummins 15L ISX at the moment so the procedure fo it was fresh in my mind. I too made a setup for it using almost the identical setup you have. However there is no recess in the cylinder area so applying the suction cap isn't a problem like it would be on your head. Anyway you're right for your application and I was right for mine. If nothing else my post gave us something to ponder.
@@tonyrmathis that’s a good point. Thx for commenting and watching. 👊
@@RelentlessRacingAJ I like to buy one r email me the parts numbers to make it bulldogjimmy45@gmail.com
@@jimhalbrook9155 everything u need to know is in the video
I need one of those...
Canyon Racer ez to build. U should make one
Its not good, the vacuum is way too powerful. even in fou introduce a HUGE leak it wont move too far down.
As mentioned, this is not the end all be all test. I merely created this tester to check if the head shop made a blatant mistake. Also, according to my research and testing, the vacuum pump is not too strong. A port will not hold over 22 in Hg if there is a small leak. If you don’t believe it, get off the keyboard and make a tester and prove it to yourself.