Low compression causes! Diagnosing burnt valve, head gasket, or piston rings??

Low engine compression causes and diagnosis! Head gasket, burnt valve, piston ring issues? This video will help you find out why you have low cylinder compression.

Follow along as I test out different products on my Volvo v70XC in the quest for the best!

Don't bother with the cheap compression testers, OTC is a good and reliable tester. Find it here.

[kirbytabor]

Timing belt broke, put new belt on ran compression test n only 2 cylinders were low, pulled head, replaced all valves in those cylinders, runs new again👍

[dylantaylor]

Everything everyone else said. First video I found that helps you identify exactly which one of the main causes it is. Thank you. I'm gonna go hopefully pinpoint my problem.

[muth]

Never thought of doing a leak down test like this. Thank you for the info, well presented.

[goldwolf]

You can do a wet compression test to confirm pistons went bad.

[litholi]

Very good job of analysis. Good technique. You gave be several ideas I had not thought of. You are probably correct, worn piston rings, not worn out, just worn more than the other 3. If you had a bore scope you could see if it was due to cylinder scaring versus ring wear, not that it really makes much difference. SInce it was 2 cylinders and not one, probably piston wear. You are also correct in your compression tester, get a good one. OTC does make good products; typically more expensive but better quality.

[nahid]

This is the best video I have found so far to diagnose the cause of low compression. Appreciate your haed work.

[vegaspitbikes]

You're the man!!! I'm using this method to diagnose my 83 Honda shadow 750. You can't get parts for them anymore so this could save me $$$$

[MyTempest]

Thats the info I needed to know. Thanks for the vid this will definitely help me out

[boogboy]

Great explanations! I was worried I wouldn't get it cause you talk fast, but those illustrations at the end were really helpful.

[mikEzShinoda]

Hello there! Amazing video, thank you! I have Skoda fabia 2005 1.4 75 hp with gasoline engine. I notice that when i park the car on a slope, around 25 degrees, on the first gear, the car is starting to roll down on stages. It's like the engine comression is gone. I read that when it starts to roll down like this, its already started to go down itself the car depot. 😃 Well the engine work so fine, without any unusual noises with changed oil, water pump, new timing belt. For about 7 000 km that i drove, the oil level went down just a little bit. I will bring it to measure the comoresion level and see if the engine is dying

[firefox]

I'll definitely have to try this, I have low compression at idle in my Chevy 4.3l v6 which causes a misfire.

[jimmiesb.johnson]

I have a 1996 4.0 chrysler/jeep inline 6 cylinder which i did this test on. The engine is out on the ground without exhaust or intake attached so its virtually impossible to warm engine before a compression test which i also did & I'll get back to that in a minute. But first, using your test all 6 cylinders leaked with piston @ TDC but all 6 DID NOT leak with piston @ between 8 - 12 degrees before TDC. Just a miniscule amount of air made the engine turn with engjne pistons between 8-12 deg. BTDC. I thought this was odd. I'm wondering if a streched timing chain would cause this?
Now back to the compression test. I had to do the compression test with the engine cold. The standard on this type of engine calls for between 120 & 150 psi. I think that is suppose to be with engine warmed to operating temp. The readings i got were between 185 & 215 psi with engine @ ambient air temp. I wasn't aware there was such a large difference in psi between cold & hot engine temps. Any insight would be appreciated. Thanks

[fatvegan]

If leaking past rings, be sure to, next, put a FEW DROPS of oil in suspect cyl. Try compression test again (wet comp test) then, turn engine over/run for a short while- check compression again. If it comes back up, and the plug that was removed from cyl was fouled (due to ignition issue having occurred), chances are the rings/cylinder walls were "washed down" by unburned fuel during the misfire event, causing the ring/s to loose it's seal. The oil you've added will re-seal and fix you're problem (IF washed down rings was indeed the cause).

Replace plug w/ new (or clean w/ lots of brake clean. Using fouled plug may start the fouling/misfire process over again.

[varathan]

Did you had engine oil consumption due to this problem?

[eddierodriguez]

My car crapped out on me getting off the highway. Before, it was burning engine oil like crazy fast. I changed my spark plugs and put in oil. This was before my car crapped out. Still doesn't start. Took it in to a mechanic who said there was low compression in cylinder #2 and #3 (both around 55PSI - should be around 165) The end result was that I would need a new engine...Does that sound right? Is there anything else I should check? Maybe take it somewhere else for a different evaluation?

[stuartwood]

What a fantastic and informative video. I'm having low compression on one cylinder on a 98 Mercruiser 3.0. The suspect cylinder had air going through and out of the carburetor and no other cylinders did that. There isn't anywhere that I can see to check for intake valve leaks. Any tips? This boat has 50 hours on the engine but sat for over 10 years in a barn. Any help or tips is greatly appreciated.

[dsrupthq]

Did this test. Thanks for the info 🤙
Between cylinders 1 & 4 I have a breach with air.
Also only cylinder leaking to exhaust is cylinder 4 but on TDC exhaust valve is open. G16B Vitara??

Car will not start, low compression.

Any ideas 😂

[hjkjccdggjhvb]

i kept getting misfire fire from the same cylinder after spark, ignition and injector replace and got all good compression but ended up with a leaking head gasket in cylinder two. So u can't really trust these test except doing a reverse power flush through the radiator and see if water is comming out from the cylinder, which mine did... and stick a camera down the cylinder

[GunsWithGage]

Video moved here from my firearms channel. Hopefully people can still find it.

[Frostensen]

Best video so far. Thank you. One question though. How would you go about cleaning exhaust valves without taking the engine apart? I know you can clean intake valves by taking the intake manifold off, but I don't understand what would you do with the exhaust ones?