I recently acquired a 93 240 Wagon and am trying to diagnose a pretty substantial oil leak from the engine. Before digging into seals I thought it prudent to service the PCV system. I confirmed this by loosening the oil filler cap while the car was running and watching it bounce up and down and spraying oil. I purchased a new oil seperator, flame trap and hoses and installed it last weekend. The seperator box was severely clogged when I cut it open. With all the new parts in I fired it up and was pleasantly suprised to see that I now had good suction at the oil filler cap. I thought that this would begin to slow down some of the leakage but it seems to be leaking just as much. Yesterday I decided to do the cap test again and noticed that after only four days the cap is again dancing up and down and oil is being sprayed out of the hole.

What gives? Seems impossible that the new box could have clogged up that quickly. Will running the test hot vs. cold make any difference? I don't have any oil spraying from the oil dipstick hole when removed. Is this bad rings,valve guides? The engine seems to run great, it's quiet and doesn't smoke at all.

 

I assume that when you replaced the oil separator box that you cleaned the flame trap as well. I would go through and check for vacum leaks. Check all vacum lines for cracking, etc. I would cap off the line that runs into the passenger compartment to eliminated that one.

Also you could do a compression test to check the health of your rings. No type of PVC servicing will help alleviate severe blow-by the piston rings.

 

"Cap dancing and oil spraying" is normal. The way you check for excess pressure is by stretching something like a rubber glove across the opening and looking for a slightly negative pressure, meaning the rubber is sucked down rather than blown out. The separator couldn't have plugged up in four days. And don't expect leaks to magically stop, seals will still have to be done...

 

where is this oil leaking from? common locations include: front and rear camshaft seals, the aux shaft seal, and the crank shaft seals. less common is the valve cover gasket.

I'd suggest cleaning the motor with some engine cleaner, and hosing it off (avoid blasting electrical parts), then drive for a couple days and see where the fresh oil is leaking out.

 

Yes, I did replace the flame trap and hoses. I didn't expect anything "magical" to happen. I knew seals would need to be replaced. What I meant, and what I thought I said was that I thought it was wise to start with the seperator box as a first step. My question was mainly about how I found it odd that I had good suction at the cap (I could feel the cap being pulled from my fingers toward the filler neck) after the box change and that just a few days later it has completely reversed.

 

Check your flame trap again to see if it is sludged up. If it's not, then obviously the separator is not clogged up already either. This would eliminate the outside possibility of the engine being some kind of a sludge belching monster. Normally sludge takes a long time to appear. Besides that, as I said in my earlier post, you don't get great suction, rather a slight negative pressure at best...

 

Right. Just to be clear I tried the glove thing too. Right after the new box was installed I felt the cap sucking toward the filler neck and also observed a slight inward pull on a rubber glove. Then a few days later the opposite. I looked at the flame trap and it still looks brand new. I just don't want to start replacing seals until I figure this out.