A compression test measure the pressure generated inside your piston bores during the compression stroke. It is a good way to determine the overall health of a motor.

A compression test will help find things like a blown head gasket, burnt, bent, or defective valves, or bad piston rings.

A compression test is performed by disabling the coil, and hooking a compression tester up to the spark plug hole. Then cranking the engine. You can purchase a compression tester at most parts stores or any auto repair shop should be able to perform one for a very reasonable price. Especially on a volvo motor which is so easy to access.

Off the top of my head I dont know the spec for compression on a b230f. I think on my b21 it was around 170psi w/ no more than 25psi variation between cylinders. If you have one cylinder with extremely low pressure it is a good sign of a blown head gasket.

I'm sure someone else will post with the correct compression specs..

Matt


--
'82 240 - 144k; '87 760T 133k