my mate just done a compression test on his car an one reading was 18psi lower than the other 3 is that anything to worry about the car is runing ok and no smoke.

thanks

 

Not worth worrying about, especially if it has a few miles.
In an IDEAL world they would all be within 10% of each other, but I wouldn't personally bother about 18%, as it means stripping bits down.
You could always do a dry then wet test to see if it is rings of valves, it is most likely valves,(or just the tester did not make a good seal on the low one).
What car is it anyway.
tabetha

 

Thanks Ill Tell Him

Its A 2wd Sapphire Cosworth Its Been Rebuilt Not To Long Back