Compression ????

[oldgradywhite]

I know you shouldn't but I did a compression test when the motor was cold and the compression was 15 pounds higher then when at operating temp. I thought the compression would go up not down when it was warm or is the a dumb question to ask?

 

[Lion hunter]

Re: Compression ????

It's like the science trick with the metal hoop (cylinder wall) and ball (piston). The cold ball will not pass through the hoop. Start heating the ring and the ball will slide through. Tight fit = higher compression in general.

 

[JB]

Re: Compression ????

Any change in conditions may cause a change in the readings. It is impossible to predict what the change may be or to explain exactly why.

That is why we recommend that you reproduce conditions as closely as possible from one test to the next, and why many of us don't really care what the readings are, so long as they are reproducible from one cylinder to the next.

So. . .you are okay. Nothing to worry about.