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Low compression

Tiny
MATT188
  • MEMBER
  • 2007 CHEVROLET COBALT
  • 2.2L
  • 4 CYL
  • TURBO
  • 2WD
  • MANUAL
  • 240,000 MILES
Hi, I recently had my car shut off and slowly lost power while driving it home. I took it to a shop and did a compression test and it said it had 8 7 14 and 10 PSI in cylinders 1, 2, 3, and 4. So I pulled the valve cover today thinking the timing chain broke but everything looks tight and in place and on the guide. I'm stumped at this point what is could be.
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Monday, May 2nd, 2022 AT 2:46 PM

1 Reply

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
If you have low compression on all cylinders, then it is more likely you have a significant failure in the head gasket or other large engine failure.

https://www.2carpros.com/articles/what-is-engine-compression

https://www.2carpros.com/articles/head-gasket-blown-test

Basically, I would suggest we do what is called a cylinder leakage test.

You do this by removing the valve in your compression tester and hooking a leakage gauge set and see how much leakage you have when you put pressure to the cylinder.

Then to find where you are losing the air, we check the oil fill cap for ring issue, coolant bottle for a head gasket. The intake valve will leak out of the intake/throttle body and the exhaust valve you will hear air coming out the exhaust.

Here is a video that will help with this:

https://www.youtube.com/watch?v=WHli-wLy9_o

Please run through this and let me know what you find. Thanks
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Tuesday, May 3rd, 2022 AT 10:01 AM

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