Low Compression

[jparry]

A mate has a golf 1.8 carb and the engine looses power while driving tested the compression and it is no1 is 9, no2 is 15.5, no3 is 15, no4 is 7. Had a thought that it could be the head gasget.

Has any one got any ideas.

[frankerooney]

9 bar is pretty low. 7 is just bad! Should be (even for a worn engine) 10 upwards, and less than 15. It doesn't look like a blow between cylinders, - this would normally show up as a low reading on two adjacent cylinders. High readings like 15.5 may be because of liquid in the cylinders (water or oil). You did this test when the car was warm right? If it was cold, the readings don't really mean much - in theory you could have leaky valve seals on the middle 2 cylinders - oil sitting on the piston and pushing the value up..? Head gasket would produce other symptoms -water in oil, oil in water, high pressure coolant system etc..