Hello everybody,
I am working on my "240" and I replaced nearly everything attached to the engine from sensors, to bushings, firetrap, hoses etc basically it should be all new and the engine should be breathing well but when I finished yesterday with this task and started the engine up for the first time since I started replacing all of it. The engine started right up but the entire engine is shaking and it is running a bit high to....but what concerns me most is that pressure inside the block...after I turned off the engine it made a sound of pressure squeezing out of the block and when I turned the oil cap you could hear the pressure being quickly released. I replaced the oil filter and changed the oil and I even added some seafoam to clean out the engine.

Does anybody have an idea what the issue could be with the pressure inside the block?

 

Did you replace the oil separator, where the flame trap goes into below?

 

yes including all attached hoses etc.

 

The pressure inside the block is caused by "blow by". That is normal (hopefully) compression leakage past the pistons. (have you checked the compression?)Your engine has a a PCV system as part of it's emissions control. (positive crankcase ventilation) On your volvo the main portion that releases that pressure is the oil trap as pictured below. You should be able to remove hose #6 and easily blow into the crankcase of the engine. If not that oil trap is clogged. The parts above the oil trap - #5 the flameshield commonly get clogged but then the hose will just blow off the oil trap. When you put it back together make sure the brass nipple that hose #8 connects too - (on the intake manifold) is actually clear and drawing a slight vacuum (with the engine running) They clog and a small drill bit is an easy way to clean them out.