Hello! This is my first time ever posting and I am hoping to gain some advice for my situation.
About 2 months ago I bought a 1987 740 turbo up in Washington and ended up driving it down to Cali for the summer. I've had very minimal issues with the car however, I began noticing oil leaking from the rear main seal and oil pan gaskets when I took the shield off from under the engine. After some research, I decided to replace the PCV system along with installing a catch can. The car now passes the glove test however, I am still getting significant oil coming from both of the seals, and it seems to be getting worse. Am I just outta luck in this situation and need to do both the seals or am I missing something? I do also sometimes get some oil coming from the filler cap.

 

If your PCV is clear then the only thing left is to do the rear main. Oil from the filler cap maybe the cap gasket. Do you have a positive or negative air pressure at the oil filler? It should be slightly negative. If not, then your PCV is still obstructed.

 

The seals(engine and transmission) on my '93 940 Turbo also leaked. So I tried this
and it worked within a few miles of driving around. If your seals are just old and dry this might help.

 

Oil pan gaskets rarely leak. The front seals can leak slightly and gravity takes the oil down and spreads it out along the pan gasket. And I've pulled many transmissions to replace leaking rear seals.

 

I just went through this, 94 940 turbo. Twice. Put the new seal in and it was leaking after installation found that the new rear main seal was thicker in the body and it offset the seal itself on the crank, so much so that it was riding on the rough surface of the crank, so it was slowly getting ground away. Ordered another, this time a Volvo part and it was the same as the older, original seal. When installing it, make sure it's a bit different than the old one as far as placement, you don't want the sealing surface in the exact same place as the old seal, the crank is a just a bit worn there.

 

I've got negative pressure out of the oil filler which is telling me the PCV should be working

 

Thank you so much im 100% giving this a try. I was also planning on doing a seafoam clean aswell.

 

Honestly, I think you might be right. After further inspection, some oil was definitely going to the oil pan via the leak from the oil filler cap. The rear main seems to be the biggest issue so I'll most likely have to get it replaced.

 

Ok, so here's an update. The oil leaks have been getting significantly worse the more I drive the car, and today I decided to re-test my PCV system. Attached is a video of me doing the oil cap test and you can see that there is a lot of pressure pushing up on the cap. I have absolutely no idea how it went from giving me negative pressure to positive pressure so fast. I replaced every part of the PCV system except for the hose that goes into the crankcase, and I'm assuming that's where my problems are coming from. I am, however, getting air pressure coming from the PCV system, so it is definitely moving some air out of the crankcase. Could I just have so much blowby that it's overwhelming the PCV system? I'm going to do a compression test to see just how bad my engine is.

 

Not a good test! Put a rubber glove on top, see what happens. The dancing cap is not a good indicator.

 

Just did glove test and it seems like the PCV is somewhat working, but I feel like I should have more vacuum. At least the glove isn't inflating. Let me know if this is good or bad.

 

I can't see the video but there should be slight suction, indicating negative pressure...