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

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.

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👍

Im sorry , I feel you. Having a big issue on a engine that costs a lot of money and its stressful but I want you to know that we got this. Stay strong guys !

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.

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

I have a Volvo XC60 D5 205 that emits white smoke after several months of being idle. The vehicle lacks power and doesn't move forward. When I accelerate fully in neutral, the engine struggles to reach 3000 RPM. During the first diagnostic check, it indicated a lack of compression in cylinder 2. After clearing the error, I received two error codes: P0100 and P0113, along with a lot of white smoke. For your information, there is quite a bit of oil around the hoses. The reason for the immobilization was that the accessory belt snapped, so we recalibrated the engine and it started.

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 $$$$

Thanks Michael

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

really loved your video! Thanks!

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

Brilliant

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

Good video

Glove Sensor ist genious

Boy I tell you what...👍

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

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

Interesting Thanx