Compression Test on Hot engine

[NJSHO]

The compression tester I just bought instructs me to to do the test on a hot engine. The problem is that I would have to take the spark plugs out and put back in on a hot engine, which I read in another thread is a no-no. Is it ok to do a compression test on a cold engine?

 

[Redline]

As far as I can recall, I have only done them on cold engines and have never had a problem...I am sure there is a reason to do them on hot engines, but I don't know whether or not that reason is worth worrying about or not.

 

[Mike Jones Who?]

the reason is so that all the metal can warm up and expand, if it is cold the seal wont be as great and could possibly show a false low compression. once it is hot the metal makes a seal and shows an accurate reading

 

[Off Road SHO]

Engine should be warm not hot, with the oil circulated well. Remove all the spark plugs during the test and block the throttle body wide open.

Tom