Piston Rings & Blowby - Explained
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- เผยแพร่เมื่อ 2 มิ.ย. 2024
- How do piston rings work? What is blowby? Why are there three piston rings? What do each of the piston rings do? Typically there are three piston rings, and they serve three major purposes. They keep combustion gases from entering the crankcase, oil from the crankcase from entering the combustion chamber, and they aid in heat transfer between the piston and the cylinder walls. The video details these processes, and also sheds light on how blowby occurs, and what happens when piston rings are worn out.
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I put new rings on a piston on my bike. I didn't measure ANYTHING. I was so pleased when I started the bike and it ran. It ran pretty well. I did 500 miles on it, including some quite tricky off-road stuff. It smoked a little. It smoked a lot. It used oil quicker than petrol. But it ran. I decided the oil use was more than your everyday break-in consumption so tore it down again and did some measuring. The rings I fitted were standard. I'd assumed the piston was standard. It wasn't. It was a full 1mm oversized. The piston ring end gaps were like the black hole at the centre of the universe. I'm still a bit baffled the bike ran at all, nevermind scrabbling up rocky mountain tracks and a few laps of a race circuit. '85 XT350. Love it.
I bet you had good compression
I like how he began using actual parts to help us easily understand his teachings. Thanks man.
The piston ring's end gap allows for expansion of the ring due to the engine heating up, much like adjusting valve lash in an engine with mechanical lifters. without the gap, the rings could start expanding outward into the bores and kill the engine.
great videos btw, ive watched almost all of them and appreciate the condensed learning within them.,
Not to mention, on a performance engine the temps are usually higher which expands the rings even more. That is probably THE major limiter on how much nitrous an engine can take, given the tune is perfect.
Not to mention also that without relief of the compression through those gaps, the piston rings could have a tendency to crack and fail.
It truly is amazing how piston rings lasts so long in car engines these days. The amount of work they have done in high mileage vehicle and yet still have little to no compression loss or blowby must be a credit to good design and probably oils that look after these thin little bits of metal.
I appreciate these videos you put out, and explaining in such a way that the layman can understand. You are the Carl Sagan of mechanical engineering.
+mygreenzebra He's not nearly as poetic as Sagan =p Which isn't a bad thing, just a fact.
+mygreenzebra Some of you are too kind with your compliments! Really appreciate it, glad you enjoy the videos!
Wow! Technical automotive videos without an obnoxious introduction nor any irrelevant details such as what you had for breakfast or your most recent sikkk modz. Thank you sir, this is great! Subbed!
+jsamhall that's my style, glad you enjoy it, thanks for subscribing!
You deserve so many more subscribers, the way you break things down and explain them is awesome. I love learning about and having the knowledge of why engines and processes work. Keep up the awesome work coming from someone interested in mechanics and mechanical engineering!
U saved my day .... has a GTI with high oil consumption. ...and wasn't getting what's the real issue for vehicle . Almost 2 weeks of restless days. The piston rings are worn out and oil gets to combustion area and burns off...
In high speed oil just becomes so thick and in 20km around 2 liter if oil gets burned ....
But in low RPM .... there's no oil burning .... actually your video made me get the actual problem for the vehicle ....
Anyway it's expensive to rip apart the engine and reassemble. ....going to do it anyway ......
Thanks a ton ...mate
Now, me and the mad scientist got to rip apart the block and replace the piston rings you fried.
I would enjoy a video regarding valve seals.
my cousin and I are rebuilding a 1990 Mazda B2200 pickup. He thinks piston 3 is leaking oil into the combustion chamber, he can't be wrong because it looks nasty. I'm glad for videos like this and others that will be helpful as we continue with the rebuild.
Finished watching all your videos explaining how cars work! Thank you for everything you've taught me, I basically knew nothing before I came across this channel.
Could you do a video on hard break-in of an engine vs soft break in please?
Do a video on Subaru's new platform explained and how it matters to future owners
I AGREE
Thank you for this video. I've been looking for a good piston ring video, and this explains them very well! Keep it up.
Thank you man. Really good presentation. Like someone mentioned-thanks for using an actual piston along with your illustrations.
No mention as to clocking the rings for proper ring position to ovoid excessive blow by?
( I learned more than I chimed in! Thanks! )
I installed total seal rings before , and now blowby is minimal.
I think I'd have em made for any engine I ever redo.
It's also Good enough to have a open crankcase vent and not get gassed out by it inside the car.
Could you could do a video on hard vs soft break-ins? Manufactures tell you to soft break-in engines, but since learning about glazing and ring seating I don't know who to trust any more. I feel like manufactures just tell you to soft break-in to cover themselves, even if it's worse for performance. But I wouldn't risk an engine on it without an experts opinion. Thanks.
Break ins have to be soft. You want your engine to be used in all kinds of RPMs in different gear ratios. Also do not stay on to certain RPM for no longer than 20-30 seconds. Do not red line your engine and do not let it idle for more than 30 seconds. So generally use different gear ratios at different speeds while not going above the recommended RPM and while not cruising for extended periods of time.
Soft break in is the way to go if you have built the motor your self. The first 50 miles are the most important for future bore and ring life. That said I don't know about a factory build as I think they run them before they sell to the public and do not build to the tight tolerance that an independent engine builder should do.
soft break in if you dont want your rings to seat
@@seemssafe2995 Bruh, you're replying to a 6 year old comment.
@@6Twisted ill do it again
Excellent, concise presentation, thank you! Loved the whiteboard in particular.
Great video as always. Picking up where you stopped the video at....id love to see a video about worn piston rings vs carboned up ring grooves leading to rings no longer able to seal correctly.
Basically, a comparison as to which is the actual culprit for blow-by.
Much like how warped rotors is a generic term for uneven rotors, when the rotors are not actually warped.
How about thicker & lighter oils on new & old car engines. EO provides lubrication and sealant between piston ring and cylinder wall. Since older engines have bigger wear and tear, does using thinner EO affect compression and combustion. vise versa. Thanks
+Tango965 Yes, engine oil provides sealing between the piston ring and the cylinder wall. If the wear on the piston ring is excessive, no oil will help sealing it. If the wear is small, a thicker oil may help. The property of engine oil that matters is High Temperature High Shear (HTHS). You can find HTHS in an oil's product datasheet. An oil with high HTHS will form a better seal between the piston ring and the cylinder wall.
icekk007 if you have VVT heavier oil will not be good for your solenoids
Hi, Can you make a video on how to remove these blow by gases from your engines' sump I am talking about the ventilation of crank case.
Thanks
Great Video! Nice, simplified explanation! Keep up these great videos!
Nice explanation and very good graphics/picture quality, Thanks a ton man 👍
Thank you! Your videos are awesome!
What is the life expectancy for piston rings? How many miles/ how many years?
Thanks again!
Timo
Some last longer than others but with regular oil changes/general maintenance you should go at least 200k miles without oil consumption. My dads Mitsubishi Outlander has 305k and I don't think it consumes any oil, maybe a very little amount.
Wouldn't the power stroke in the cylinders be more susceptible to blowby squeezing past the rings rather than during the exhaust stroke, when the spent combustion gases already has exited the cylinders? Blowby happens when combustion pressures seep past the rings and make its way through the crankcase and out the vents, taking oil vapors with it into the intake, correct?
+OCTurboJoe I know what you're getting at but the blowby doesn't "squeeze past the cylinders" in one go. Look again at the diagrams in the video. It happens in two stages:
1) The exhaust stroke forces the rings DOWN letting gases into the top part of the gap.
2) The compression stroke now forces the rings UP which releases those gases out of the bottom of the gap.
It is a two-stage process. It would take an incredible amount of power to blast those gases past the rings in one go. Maybe if the rings were very worn though.... Hope that helps.
+Boysya Exactly. It's more pronounced with force induction. A newly built engine with a fresh set of rings can still have a good amount of blowby. Pressure will always find the past to least resistance, especially through rings on the power stroke. The exhaust stroke is more like negative pressure where gases exit the chamber vs positive pressure pushing past the rings, into the crankcase, and out the vents. This video probably explains blowby at idle whereas I am explaining excessive blowby under load.
+roadrunnerblink he didnt describe it well, in fact most blowby is caused by bad ring to cyl seal, not by a tiny amount of space behind the ring
Always great demonstration and explanation. Great job!!!
I think your videos are awesome there are informative and thoroughly explained by yourself, but sometimes you go through quite quick in videos and i get a little lost & confused as im no engineer like yourself, but i am learning slow but surely..;)
Thanks again for sharing your knowledge of engineering and mechanics, and please keep the vids coming.
Peace.
sir, can u make a video on Hard break-in. I really like how you explain things with engineering point of view, appreciate it so much...thanks
That kinda ended abruptly. I was hoping for more details.
AeroElectro that’s what she said
@@GreatGrandmasterWang LOL!! 🤣🤣
@@GreatGrandmasterWang 🤣🤣🤣😂
dude! 30 seconds into this video and I knew this was going to be informative, good job
Great explanation. Thanks for the great vid. Subscribed!
Could you please make a video about breaking a car in? Mythbusting or the usual.
The topic is so controverse, but also so important.
Cheers!
no fast and furious remarks? interresting
this vid answered a few questions I've been thinking of. subscribed!
thank you for sharing technical knowledge...
I believe piston rings in an engine form whats called a "labyrinth seal"
+Bill T Labyrinth seal is not used in piston ring. I think it is generally made of elastomer (rubber) material, so it can withstand the heat and pressure experienced in a piston. They are generally used in shaft seal in rotating machines.
Bill T Labbys are on rotating assemblies as was mentioned, but they definitely don’t have to be soft like rubber.
Yes it is a variation of the labyrinth passageway, you don't line up the ring gaps all in a row for this reason
what metal are these rings made of? I always thought they're rubber.
Same
Not since the early 1900s has that been true. They are made out of a very hard, springy, and brittle steel.
+Jean-Paul Veillon Oh!
cast iron
+Mohamed Li Usually cast iron for the Top Ring, cast iron or steel for the Second Ring, and steel or stainless steal for the Oil Control rings
Fantastic explanation. Thanks for the great diagrams and use of real components for demonstration.
You are like my personal teacher. Keep up the good work!
explain PCV valves please
+TheWolvesCurse essentially, you have a valve on your crankcase that lets air/fuel out of your crankcase back into the intake manifold.
When the vacuum pressure of the intake manifold/throttle body is in the correct range, the PCV valve opens and uses that vacuum to pull blowby gasses out of the crank case and pull it in to the intake and reburn it. Its an emission control system. If that valve is stuck open, you could suck up engine oil and cause all kinds of issues with the intake or throttle body.
In other words...if you own an STi, buy an Air Oil Separator.
Really good demonstrations in all your videos. Thanks
Although I already knew what piston rings do; I wanted to watch this video and it is as accurate and even better than I could have described their purpose! 😊
Blowby = Volkswagen TSI engines
Yep
you should go wayyy deeper into this subject. You could make a 30 min video if you went deep.
+fightfanian how deep? Really deep?
+Mike Halpert balls deep
+fightfanian like hodgetwins sugar walls deep?
+fightfanian A Basic overview gets the job done in :05 minutes. Well Done!
+fightfanian I was actually expecting that...
Very informative video thank you.
I was going to ask about Engine knock but then found your video from 2014.. Nice one lad, you have us nicely covered..
Why are cylinder rings so much more reliable and durable than the Apex seals in a wankel engine?
simply that the heat is more intense and builds up on one side of the block more than the other, so there are more cooling issues to overcome.
Plus the oil, if not regularly topped up with the correct type will mean that there is more wear on the seals. Not to mention that the wall exhausts in the standard 13b design mean that they are regularly passing over the port which can cause some wear when it touches the other side (overcome in the renesis MSP design). The oil used however, even in this design doesn't burn 100% cleanly, so the residues that build up will cause seal wear and degradation over time.
2T Premixed fuel and SOHN oil reservoirs do help in reducing these types of wear, which would be nice to see this channel cover.
***** ***** thanks! That makes sense;)
Thank you Jason. Good explanation as always.
Wow, I was expecting it to be longer, but it was actually 3:50!
So good job explaining that time went super fast.
Hey Jason, love your videos have almost watched them all, helped me so much giving me a visual example on some tricky stuff so thanks for that. Now, could you possibly do a video on stalling hydraulics in heavy diesel machinery, I have read a bit on it but would love to see you do a video on it to help me understand, thanks again!
Great video, thanks for the explanation. Those look like the newer type of rings that you can install without any tools. They look so flexible which helps reduce drag on the cylinder wall and increase mpg (change oil regularly to prevent sticking). It would be nice to have technology to produce an artificial layer of diamond surface in the bores and a coating on the rings to inhibit wear.
This is was a well explained video! Loved how he used an actual piston to explain the workings of the rings. I’m learning little by little and never cared for this stuff till I became a car owner and now want to learn the basic stuff and how they work so I can properly care for my first ride. Thanks man for this helpful information much appreciated!
Might do a vid on the different configurations of rings, cyl walls, Nikasil, cast iron and the advantages and disadvantages. Great video as it is.
Great!! Simple, detailed and very quick. Keep it up!!!
WOW you are awesome Engineering explained. I discussed this topic with someone from the comment section like 2 days ago. And some said this topic was to small. yet you made the video I wanted. thank you so much. Have a nice day :)
Breaking in a new engine is something everyone and their brother has an opinion about. One might say to take it easy on a new engine for the first 1k miles. Another might tell you to drive it like you stole it in order to "set" the piston rings to the cylinder walls. This video got me thinking about those opinions. You should make a video on the proper way to break in an engine (if their is one) and what you should or should not do. Love your videos by the way!
Excellent video as always.
Wow great explanation. Easy to understand.
Great quick explanation. Easy to see why you should do regular oil changes.
I just learn this from your channel. Great one!
Excellent video! You could go a bit further and describe ring flutter and more issues caused when crankcase pressure is allowed to be present creating instability creating more wear and blow-by. This is common when tuner shops don't understand the functions of the PCV system and proper crankcase evacuation. You always want to pull suction on the crankcase to maintain proper stability and ring seal. When this is defeated and breathers added to "vent" your allowing pressure to be present. It is not hard to install a crankcase evacuation system that pulls suction at all times emulating a belt driven vacuum pump for the street. Good video!!
great video, very nicely explained! subscribed
Thanks, this channel really helped me a lot to learn for my Job in Shell.
Just now learning about something I have used for 55 years. So what happens to the gas that passes into the crankcase and is pressure inside the crankcase a problem. Thanks for your presentation. Extremely well done.
I would just like to have you teach me everything engineering. I really learn a lot from you.
Working on a single cylinder engine from a mid '30s italian motorbike I was taught that, when it is time to reassemble it, it is better to place the "gaps" in the rings 180° one from another. That way you increase the lenght of the path for the blowby gases therefore reducing it. I also think that the rings can somehow rotate when the engine operates so that may be partially true.
Helpful and easy to understand vid. Thx.
Absolutely love these videos
Great explanation as usual. Thanks.
love this guys videos!
You are the Mr. Wizard of cars!
thank you very much.
your video is very helpful in understanding the concept of blow by.
keep makinh videos like this.
again thank you
Another excellent video!
awesome video. very informative
Great explanation. Thanks!
GREAT EDUCATION!!!! THANKS FOR SHARING!!!
Nice and informative.... God bless you
Very beautiful & rational explanation, thak you!❤
wheo, 4k vid. nice job! really apriciated! keep it up!
good explanation ...great job
Good video man, thanks!
Awesome video! 👍🏼
Excellent vid, thanks!
even if you have a brand new engine it will have Blowby cause the rings can't seal 100%, some of the combustion gases will enter the crankcase it will mix with the engine oil so that's why you need to change the oil on regular bases and also causes presure buildup in the crankcase. For control of the pressure inside it, a PCV (positive crankshaft ventilation) is used to vent the crank case,is an inexpensive and often overlooked component until you wake up whit a blown oilpan or valve cover :)),i know this vid was about piston rings but as you can see one thing thake you to another and so on,good video by the way \m/
Show your videos to my students as they are well present and easy to understand.
Thank you so much! That was really educational! :D :D
very nice explaination. Thanks sir
Extremely helpful, thank you man.. so my motors junk unless I replace those rings... good to know.
Great video! Thanks!
Excellent Video as always..my question is, is there anyway to set you piston rings after hone your cylinders walls. I did a leak-down test on a few of my cylinders and found that a few of them was low 20 percent leakage. the leak down showed that the air was coming from the crankcase. so i took them out, hone out all the cylinder that were low. the pistons and rings are now back in which brings me back to my question above. thanks for your feedback
Engine oil also helps to create a seal within the rings. The scraper also helps with portioning the amount of oil that is allowed to stay in the cylinder to keep things sealed and lubricated. Interestingly enough, the pistons on aircraft engines do not have those weep holes because you're dealing with bore sizes over 5".
very helpful video for people like me who only have hands on knowledge of suspension/brakes/wheels etc. but haven't done any sort of internal engine work.
Thank you so much mate.... this clears my doubt about blow by
Hey Jason, thanks for the awesome explanation as always! I was wondering why does the piston ring grooves allow a vertical play for the piston rings. I think that if there weren't any vertical play, the exhaust gas would not get in to the grooves and make its way down to the crankcase. One explanation that comes to my mind is may be it allows the first piston ring to have less stress on it by allowing the play. Can you please elaborate on this? Thanks!
Perfect and precisely explained.. thnx
I would be really thankful to you sir if you explain about the practical working of manual transmission of bikes and cars
That was a Excellent explanation
I was super hoping you would have a video up for the new Formula 1 Engines (Mainly the Hybrid System) for the season opener this week.
Great explanation of piston rings though!