Quote:
Originally Posted by lietuviai
The FSM suggests doing it on a fully warmed up engine. That info is straight from the people that designed the engine. Doing a test on a cold engine will not accurately diagnose any engine problems. An engine is only cold for a short period of time. Most of the driving is done with the engine at full operating temperature. Does it make any sense to run tests on a cold engine if most issues occur when the engine is fully warmed up?
BTW, I wouldn't trust any tool from HF to accurately test anything. I'd bet their gauge would be off +/- at higher readings compared to a true professional gauge.
|
DJ, I'm not picking on you bro, just the concept.
I know thats what is suggested, it's because everything warms up expands, and seals up, which will give you higher compression, and a better picture of what's going on with a running issue. Which is important.
But I ask why then, when we all go look at a potential purchase of our beloved diesel cars, do we want to start it cold. Beacuse it tells you how good the compression is. If it fires right off on a blustery cold day, you know you've got a tight engine, if it takes some doing to get is started you know the engine is getting a little tired. And why is is getting tired, amongst other things, compression.
I guess it comes down to what you're trying to diagnose. Cold starting and cold running issues, then I'd suggest a cold compression test. Warm running issues, then a warm compression test.