This was a HUGE help! Thank you and keep it up. I go to your videos first for all my 12 valve needs. I've been doing black diesel (because of you) for almost 2 years and have saved a ton. I now run a shop and have more oil than I need and have a waste oil furnace too. I have been debating about this bypass for a while.
I have been modding the gasket for better flow on 6 and 5. I see what you are saying though. It was not entirely clear to me before how the coolant flowed, but you have made that clear. Now the bypass makes a bit more sense to me.
Thank you for this great information! I bought my super duty already swapped and it doesn't have a bypass but with this new knowledge of how the coolant flow goes I'm thinking about changing some stuff on my coolant system! Thanks!
This is a good informative video on coolant flow. I chose to pull coolant from the second port forward from the back of the head and use a ball valve as a restrictor as well as having the thermostat still. My figuring is, it'll bypass a little all the time but when the coolant pressure increases at the rear of the head, it has a path of less resistance to the radiator. I keep it restricted partally to make sure it doesn't starve the front of the head of coolant or affect the flow direction. Thoughts on the setup? Could also replace the valve for a spring pressure release.
You mentioned a second radiator. I need more cooling! After compound turbos EGT control is no longer a problem. Water temperature is my next problem. 1997 with a manual transmission.
Definitely would be interested! I was trying to figure out a way to fit the bypass in my 76 Chevy k20 with a 1st gen industrial engine from a school bus.
2 of the Case Maxxums I used to service on a hay/beef farm I worked at used the coolant ports in the side of the head. The lowest rated horsepower unit (think it was a 5230) had the Lucas CAV DPA injection pump on it, really an odd pump if you were used a lot of the “normal” Cummins stuff.
Flow is better to describe this than pressure. Because as soon as the thermostat opens the entire system including the radiator has pressure. But it flows away from the pump back into the pump. None the less good video
I have a 1st gen with second gen rad and intercooler. Just had to do some masaging on the firewall to make everything happy. But a direct bolt in would save alot of fabwork.
You missed some info. The heater lines help cool the head by increasing flow. The other issue is that when you pull some of the coolant off the back of the block you also lose some flow through the head.
Cummins makes a part for I believe industrial engines and generators 3925226, I believe a few guys say they fit/clear on 1st gens and they also tie that into the port near the inlet rad hose I believe it’s a 3 way fitting for the heat exchanger.
@@XxOverLoad93xX out on the block into the non pressure side is what you want in any application. But it you just use the plate you will want restrict coolant flow otherwise the engine won’t get hot. That’s the reason that on a coolant bypass you run the thermostat or a pressure relief.
I wish I could run that style, I put a zf5 behind my 12valve and the trans mission bellhousing blocks the rear plug. So I ran mine from the rear most port on the driver side of the head. Can’t run a thermostat but I live in the middle of the desert so it works out
I commented on his video when it came out recommending not to run it that way, he responded saying that he followed the instruction fleece sent. So apparently fleece is saying to plump it into that pressure port?
By the way he talks I think he think the coolant moves the other way in the block. Fleece tells you to put the line to the top tstat housing. Which is after the stat free flow into the top rad hose.
So if you essentially route your trans heat exchanger into one of the thread plugs on the exhaust side of the head there would be no flow if you do that right cause of pressure cancellation
need the coolant bypass to grab hot water from the back end... because the water in the pump recirculation zone gets cooled off from the radiator's down draft. hot cab heater
cylinder head flow goes down, keeps the injectors worm. 180*f is to hot, gauge should never go past 165*f. "heater recirculation blocked off at the water pump" 2.5" pickup pipe vs 3/4" bypass for heater... forces a water pressure change in the system where it pulls water out of the thermostat valve as the 3/4~1" bypass tubing is nowhere near big enough to fully bypass anything.
Coolant with even cylender temps is only half the story... I have a twin ram on my 12v and regardless what people say, I'm running cooler egts!! Knowing that, how hot did #5,6 cylenders get! I pull all the time 10k lb. Enclosed trailer 23" and 7' tall . No issues.
You totally can circulate it into the lower rad hose, then you would increase the circulation and the main thermostat would open more and accomplish the same thing. The other thing that should be noted is that when you increase flow through the block you’re 100% impacting the total flow through the head. Plumbing the bypass into the heater core is ridiculous. It wouldn’t do anything if it was actually cold out. That is an anti cavitation port beside the thermostat. It feeds the water pump fluid to keep it moving. “People don’t understand” even you don’t understand.
👍👍..picked up an OEM ,cast iron,by pass adapter( think it was for a Marine engine or something)... pretty cheap... haven't installed it...was gonna try on a tow rig eventually... probably just T it into the heater core..or route it to radiator or bottom rad hose adapter...idk, we'll see.but anyway 👍👍👊
@@XxOverLoad93xXcuz you are putting hot water into the water pump intake. It would function as a pressure relief but do nothing for improving cooling performance thru the block. That being said I personally feel dumping the pressure is the only real use for a bypass as if you are using it to cool cylinders to keep them from scuffing due to excessive egt you are killing your cylinder head more by robbing it of some of its flow because it’s easier for water to go out the bypass than turn and flow back thru the head so running a bypass just takes coolant away from the head which also suffers from excessive egt in the form of excessive guide wear and cracking. In my opinion If you want to turn a bunch or rpms and run a closed thermostat run a spring bypass. If you won’t turn over 3500rpm don’t worry about it or if you are racing and don’t need a thermostat don’t worry about it either.
@@bcbloc02 running a coolant bypass does in NO meaningful way reduce flow to the cyl head, the flow rate (volume per time)per system pressure drop formula is a quadratic formula. the pressure measured at operating temp (190f) through and AN fitting freeze plug in the back of the block @ 3000-3500 rpm is 50-70PSI. the problem with the cooling system isnt its performance, if that was the issue you would just change the rad, the problem (like most front to back cooled inlines) is that the coolant has picked up too much heat by the time it reaches the back of the engine. Most of the restriction in the coolant flow path is the cyl head, the cummins water pump has PLENTY of flow, by adding a 5/8 ish -10 and fitting line at the rear of the block AHEAD of the cyl head restriction what you are doing is significantly increasing the flow through the block (think of it as a manifold supplying the head and the bypass now), whilst insignificantly reducing the flow to the head. this has multiple effects, the rate of heat transfer has a direct relationship with delta T, meaning that your watts of heat rejected from the system per time INCREASES as the temperature difference between the engine and the coolant grows. The increased rate of coolant movement in the block because of the bypass means that time spent at the front cyl cooling jackets is less, meaning less heat absorbed by the coolant by the time it reaches the rear cylinders, and that in turn means that the rate of heat transfer to the coolant at the rear cylinder is also increased, aka more even cooling across the block which is the REAL issue, not overall cooling system performance. in my opinion (id have to do an actual experiment with temp probes before and after in the cyl head) the cylinder head receiving coolant that is a lower temp more than offsets the single percentile reduction in flowrate you'll see with the bypass kit installed. this also eliminates the stagnant area behind cyl #6 where coolant will just eddy and only exchanges out via convection and eddy. All that being said, if you have a more or less stock truck, 185hp 12v or 24v and arent seeing rpms north of 3k, id agree that the kit doesnt really offer much, itll make your rear cyls run a LITTLE cooler, but i havent really seen many people have issues in 5/6 with stock trucks till the 3rd gens came out with their higher HP and more demand of the cooling system.
You might get a small amount flow out of it a certain times. But it would be flowing to help. You want to move coolant from front to back. That would flow from front into the back.
@@SmokeShow2007 I shouldn’t have to explain this, but here goes… if both discharge and suction is equal there there is no restriction. The Pump is a MECHANICAL mover. It will physically move the water granted to a certain point as water pumps are not positive displacement pumps, but they will absolutely still pump. If this were a system that was designed without a pump that worked solely off of pressure then sure. But that’s clearly not the case. If you look at early 24v’s the pump would literally build so much pressure it could and did crack cast iron blocks the old infamous 53 blocks. In what universe do you think that’s not enough mechanical force to move water through ESPECIALLY when pressure is equalized! It can crack a cast iron block but it won’t move water that’s NOT restricted. How do intercooler systems work then? There’s no Delta on most of those. You’ve never circumcised an old unsplit 53 block’s water pump so it wouldn’t split before I take it.
I definitely need one in my 1st gen! Great video! No one else dives deep into these engines like you do!
Do my best to help a guy. I will get in to the later stuff. But want to get the old stuff done first
@@CUTTERUPROB I appreciate that!
Great video and info Rob. So many people don't understand the flow through the block.
This was a HUGE help! Thank you and keep it up. I go to your videos first for all my 12 valve needs. I've been doing black diesel (because of you) for almost 2 years and have saved a ton. I now run a shop and have more oil than I need and have a waste oil furnace too. I have been debating about this bypass for a while.
Thanks for watching and glad I can help
I have been modding the gasket for better flow on 6 and 5. I see what you are saying though. It was not entirely clear to me before how the coolant flowed, but you have made that clear. Now the bypass makes a bit more sense to me.
You’re the man Rob. Please keep it up. You are appreciated!
Thank you for this great information! I bought my super duty already swapped and it doesn't have a bypass but with this new knowledge of how the coolant flow goes I'm thinking about changing some stuff on my coolant system! Thanks!
I have a first gen and I’d be very interested in a coolant bypass that fits. Great video!
Yes please make us a 12 valve coolant bypass Rob!!! The world needs you! ❤❤❤
This is a good informative video on coolant flow. I chose to pull coolant from the second port forward from the back of the head and use a ball valve as a restrictor as well as having the thermostat still. My figuring is, it'll bypass a little all the time but when the coolant pressure increases at the rear of the head, it has a path of less resistance to the radiator. I keep it restricted partally to make sure it doesn't starve the front of the head of coolant or affect the flow direction.
Thoughts on the setup?
Could also replace the valve for a spring pressure release.
I do the same thing on stuff I drive in the winter. I close the valve off when not towing.
Yes for sure I want one for my first gen
Thanks for this info
Always excellent info, thanks Rob !!
@@bdjm8595 thanks man
Thanks for the VERY useful information! I will be utilizing this soon.
You mentioned a second radiator. I need more cooling! After compound turbos EGT control is no longer a problem. Water temperature is my next problem. 1997 with a manual transmission.
I would add an oil cooler. I will have some videos coming up talking about it
Same situation, but 2004.5 Commonrail NV5600. I can raise coolant temps 20-30* on a reasonably sloped hill and never break 1250*EGT
Definitely would be interested! I was trying to figure out a way to fit the bypass in my 76 Chevy k20 with a 1st gen industrial engine from a school bus.
I have an unrelated question. I have 230 hp 5.9 12v in my motorhome and have to replace the block are all 12v blocks the same even out of the pickups?
2 of the Case Maxxums I used to service on a hay/beef farm I worked at used the coolant ports in the side of the head. The lowest rated horsepower unit (think it was a 5230) had the Lucas CAV DPA injection pump on it, really an odd pump if you were used a lot of the “normal” Cummins stuff.
I have work lots of those piles lol
Flow is better to describe this than pressure. Because as soon as the thermostat opens the entire system including the radiator has pressure. But it flows away from the pump back into the pump. None the less good video
Thanks for the video good information 👍
@@claytonleckie9924 thanks for watching it.
I have a 1st gen with second gen rad and intercooler. Just had to do some masaging on the firewall to make everything happy. But a direct bolt in would save alot of fabwork.
I'm interested in the 1gen coolant bypass.
You missed some info. The heater lines help cool the head by increasing flow. The other issue is that when you pull some of the coolant off the back of the block you also lose some flow through the head.
Cummins makes a part for I believe industrial engines and generators 3925226, I believe a few guys say they fit/clear on 1st gens and they also tie that into the port near the inlet rad hose I believe it’s a 3 way fitting for the heat exchanger.
Yep they do. We are making one the has the thermostat in it that fits
@@CUTTERUPROB would it be beneficial with Tstat vs w/o a Tstat plumbing it into that port on the coolant intake vs going on the outtake?
@@XxOverLoad93xX out on the block into the non pressure side is what you want in any application. But it you just use the plate you will want restrict coolant flow otherwise the engine won’t get hot. That’s the reason that on a coolant bypass you run the thermostat or a pressure relief.
I have an old 4bt in a case bobcat it has the same fitment as the 6.7 at the back of block
Id get one for sure
Would be interested if this is a good idea for my 6.7 compound VE pump build
@@nephron9924 it’s a good idea on any b series Cummins I think
I'm interested
Your the nacho guru
I wish I could run that style, I put a zf5 behind my 12valve and the trans mission bellhousing blocks the rear plug. So I ran mine from the rear most port on the driver side of the head. Can’t run a thermostat but I live in the middle of the desert so it works out
Might be coming. The guy I working did one for his. But requires the plate to be modified
@@CUTTERUPROBif you make it work I’ll def take one
@@Dopey_m send me a email or message on ig I will show you the one he made
I commented on his video when it came out recommending not to run it that way, he responded saying that he followed the instruction fleece sent. So apparently fleece is saying to plump it into that pressure port?
Instructions*
By the way he talks I think he think the coolant moves the other way in the block.
Fleece tells you to put the line to the top tstat housing. Which is after the stat free flow into the top rad hose.
So if you essentially route your trans heat exchanger into one of the thread plugs on the exhaust side of the head there would be no flow if you do that right cause of pressure cancellation
The heat exchanger will pull coolant off the head. Then goes back to the lower radiator hose pre water pump. So it flows
But what if it’s already being fed from the heat exchanger hole in side of block under the fuel bowl
@@daviderickson6933 you can feed from the block side to the head. Some applications to that. Depending on what your working with and trying to do
So what you’re saying is it flows the reverse of what I thought. But actually goes from the head to that hole
Ok thanks for answering man
need the coolant bypass to grab hot water from the back end... because the water in the pump recirculation zone gets cooled off from the radiator's down draft. hot cab heater
cylinder head flow goes down, keeps the injectors worm. 180*f is to hot, gauge should never go past 165*f. "heater recirculation blocked off at the water pump" 2.5" pickup pipe vs 3/4" bypass for heater... forces a water pressure change in the system where it pulls water out of the thermostat valve as the 3/4~1" bypass tubing is nowhere near big enough to fully bypass anything.
Coolant with even cylender temps is only half the story...
I have a twin ram on my 12v and regardless what people say, I'm running cooler egts!!
Knowing that, how hot did #5,6 cylenders get!
I pull all the time 10k lb. Enclosed trailer 23" and 7' tall .
No issues.
Coolant temps is only part of the equation for sure.
You totally can circulate it into the lower rad hose, then you would increase the circulation and the main thermostat would open more and accomplish the same thing. The other thing that should be noted is that when you increase flow through the block you’re 100% impacting the total flow through the head. Plumbing the bypass into the heater core is ridiculous. It wouldn’t do anything if it was actually cold out. That is an anti cavitation port beside the thermostat. It feeds the water pump fluid to keep it moving. “People don’t understand” even you don’t understand.
Hey sorry kinda off topic. I got an 18 6.7 ima throw on a old webasto. Is there a good way to plumb it in and get the block to warm up better?
If it deleted you can just use the lines that went to the egt
@CUTTERUPROB just went ant looked at it. Your right that's a great spot
👍👍..picked up an OEM ,cast iron,by pass adapter( think it was for a Marine engine or something)... pretty cheap... haven't installed it...was gonna try on a tow rig eventually... probably just T it into the heater core..or route it to radiator or bottom rad hose adapter...idk, we'll see.but anyway 👍👍👊
If you hook to bottom rad hose then it’s useless
@@diederrr why
@@XxOverLoad93xXcuz you are putting hot water into the water pump intake. It would function as a pressure relief but do nothing for improving cooling performance thru the block. That being said I personally feel dumping the pressure is the only real use for a bypass as if you are using it to cool cylinders to keep them from scuffing due to excessive egt you are killing your cylinder head more by robbing it of some of its flow because it’s easier for water to go out the bypass than turn and flow back thru the head so running a bypass just takes coolant away from the head which also suffers from excessive egt in the form of excessive guide wear and cracking. In my opinion If you want to turn a bunch or rpms and run a closed thermostat run a spring bypass. If you won’t turn over 3500rpm don’t worry about it or if you are racing and don’t need a thermostat don’t worry about it either.
@@bcbloc02 running a coolant bypass does in NO meaningful way reduce flow to the cyl head, the flow rate (volume per time)per system pressure drop formula is a quadratic formula. the pressure measured at operating temp (190f) through and AN fitting freeze plug in the back of the block @ 3000-3500 rpm is 50-70PSI. the problem with the cooling system isnt its performance, if that was the issue you would just change the rad, the problem (like most front to back cooled inlines) is that the coolant has picked up too much heat by the time it reaches the back of the engine. Most of the restriction in the coolant flow path is the cyl head, the cummins water pump has PLENTY of flow, by adding a 5/8 ish -10 and fitting line at the rear of the block AHEAD of the cyl head restriction what you are doing is significantly increasing the flow through the block (think of it as a manifold supplying the head and the bypass now), whilst insignificantly reducing the flow to the head. this has multiple effects, the rate of heat transfer has a direct relationship with delta T, meaning that your watts of heat rejected from the system per time INCREASES as the temperature difference between the engine and the coolant grows. The increased rate of coolant movement in the block because of the bypass means that time spent at the front cyl cooling jackets is less, meaning less heat absorbed by the coolant by the time it reaches the rear cylinders, and that in turn means that the rate of heat transfer to the coolant at the rear cylinder is also increased, aka more even cooling across the block which is the REAL issue, not overall cooling system performance. in my opinion (id have to do an actual experiment with temp probes before and after in the cyl head) the cylinder head receiving coolant that is a lower temp more than offsets the single percentile reduction in flowrate you'll see with the bypass kit installed. this also eliminates the stagnant area behind cyl #6 where coolant will just eddy and only exchanges out via convection and eddy. All that being said, if you have a more or less stock truck, 185hp 12v or 24v and arent seeing rpms north of 3k, id agree that the kit doesnt really offer much, itll make your rear cyls run a LITTLE cooler, but i havent really seen many people have issues in 5/6 with stock trucks till the 3rd gens came out with their higher HP and more demand of the cooling system.
@@EvanWSH 👍👍👊
Our boy does not get the exposure he deserves.
@@zjeepgozweeln thanks brother
Wait why don't fleece fit in the first generation?
They come out to far from the block
How do you tag deboss?
Doesn’t let me for some reason
150 Aus on eBay 😅
Not following Rob, even with equal pressure if piped properly it’ll still flow. Something about a pump.
Wrong man. It will equalize and just not move any fluid.
You might get a small amount flow out of it a certain times. But it would be flowing to help. You want to move coolant from front to back. That would flow from front into the back.
@@SmokeShow2007 🤣🤣🤣🤣🤣
@@SmokeShow2007 I shouldn’t have to explain this, but here goes… if both discharge and suction is equal there there is no restriction. The Pump is a MECHANICAL mover. It will physically move the water granted to a certain point as water pumps are not positive displacement pumps, but they will absolutely still pump. If this were a system that was designed without a pump that worked solely off of pressure then sure. But that’s clearly not the case. If you look at early 24v’s the pump would literally build so much pressure it could and did crack cast iron blocks the old infamous 53 blocks. In what universe do you think that’s not enough mechanical force to move water through ESPECIALLY when pressure is equalized! It can crack a cast iron block but it won’t move water that’s NOT restricted. How do intercooler systems work then? There’s no Delta on most of those.
You’ve never circumcised an old unsplit 53 block’s water pump so it wouldn’t split before I take it.
@MechanicalMafioso Maybe if there wasn't multiple passages.... water goes the path of least resistance.
❤️🔥🇺🇸😎
How about these big Radiators,ever clean one out???
I have a 99 F-800 with a 12 valve