Low compression with engine light and Stabilitrac warning light

2006 CADILLAC DEVILLE DTS
81,000 MILES • 0.5L • V8 • 2WD • AUTOMATIC
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EUGENE PARKS JR
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Has ran flawless since day one. Going down freeway warning light came on started missing badly. I drove several miles to a garage. The mechanic told me that cylinder #8 had a low compression and therefore he would have to tear the engine down or did I want to replace the engine. My thought's are wow.
This was terrible news to have to hear since I work 150 miles away at a boys camp and I just arrived to hear what this mechanic felt the problem was. Any advice, I truly like my car it's been great and for it to come to this in just a few seconds. I truly feel it's something not so grave. Any advice?
May 31, 2019 at 10:12 PM
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KASEKENNY
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Hi Eugene,

Sorry to hear that. Did he tell you what the compression reading was and what the other cylinders were?

If it is truly low and he is correct then unfortunately, he is correct. However, he doesn't need to tear it down just to find what it is. He needs to run what is called a cylinder leakage test. This is basically closing that cylinder up by rotating it until the valves are close, and applying air pressure through the spark plug hole. Then he looks for air escaping through the cooling system, air intake, exhaust system or crankcase. Once he finds where it is escaping it will tell him what has failed. Either the intake or exhaust valve, head gasket, or piston rings. No matter what he is most likely tearing it down but then at least he knows that he is looking for rather than getting in there and hoping to see something. If it is not obvious then the last thing he wants to do is guess or tell you it needs an entire engine when it just needed a valve.

Let me know if he gave you the readings because depending what they are, it could change the path and we can go from there. Thanks

https://www.2carpros.com/articles/how-to-test-engine-compression
Jun 1, 2019 at 12:04 PM