I am in the process of replaceing my friends head gasket and before I started I did a compression test on the other head and it has 75# in both cylinders 2&4. So I am assuming the compression should be around 125# and that this other head gasket is also bad, correct?

Joe

There's not much else besides a blown headgasket that would cause compression to be down only on one bank of cylinders...

What is the normal range for compression?

On my 87 wagon I have 125#

I have read that if the cylinders are within 10% of each other not to worry as compression varies from car to car.

I know 1 head gasket is blown.

Joe

broken or jumped Timing belt could throw compression off on 1 side.

125 psi isn't a bad reading for a motor with 150k or so, IMO.

 

I've seen EA82 motors down to 90psi with headgaskets that were holding, and the motor still running well.

 

75 would definitely be on the low side. Sure sounds like a HG, but I wouldn't rule out some other possibilities (like carbon build-up) if the other tell tale signs of a blown HG aren't there.

 

good luck, John