I've noticed a small oil drip that I find annoying on my B230F in my 89 740. Its on the left side of the engine block and seems to come from the underside of the oil separator box thing. The flame trap and all the hoses etc are clean and clear but I'm wondering how to remove the box to change the seal? There is a seal that connects the box to the engine block right? I assume that's where the oil is coming from....it sure looks like it.

What causes this leak? Is it a common place for oil drips?

I would say you're on the right track. The sealing o-ring is probably pretty hard by now and not doing a very good job.

Is there a way to clean out the existing oil trap box? I see that ipd etc have them for sale relatively cheap but instead of buying a new one can the old be cleaned and a new "O" ring installed?

Thanks for the help..

Yes. there are a number of threads on this but the basic premise is the same:

Uninstall the oil separator
Beat it with a stick (use appropriate force not LAPD levels of force)
Clean with kerosene or similar
Repeat until it weighs about 30% of what it weighed when you removed it

The cheap oil separators have gotten a very bad name for failing at the weld. You are better off fixing the old one. The process is no difficult but very tedious as the carbon combined with the sludge really does not want to be liberated from its home.

So was this box designed to be replaced from time to time because it would become full? Its so different than anything I've ever seen on other car manufacturers b4.

Thanks....

Not really designed that way. Oil separators are pretty old school and still used on a lot of industrial motors. With regular oil changes of high quality oil on a non-turbo doing say 10-15K miles a year with half city and half highway you are probably looking 200-250K miles before it would get coked up.

I have only had to deal with once on my 1990 240 with on 110K miles...in 2012! My other Volvo's all have in excess of 200K miles with no sign of the issue. That car did more sitting and being neglected than it did driving. My suspicion is that it got an oil change every 5K miles or 3 years whether it needed it or not which contributed to the early coking. My guess, your car did some sitting for long periods of time.

Folks that run full synthetic report never having to touch anything in the PCV system again (if it is clean and clear when they start) so there is that option once you resolve this.

Yes, the car sat for aprox 5 years before I bought it and brought it back to life.

You think that time spent undriven has caused such an issue? When I bought the car there were no signs of an oil drip under the car...ever. It was after I went through all the systems and started driving it that the oil drip began.

Engine seals dried out in five years. Give car more time for oil to re-wet and expand seals.

The oil trap seal specifically is cheap and I would replace. I don't think it's worth cleaning old traps, get new genuine Volvo one.

I cleaned mine a few years ago . I bought a brand new one but decided to soak the old one overnight and beat it to dislodge the crud inside. It was much lighter in weight afterwards. The build oem quality was much better than the replacement one I had bought.I replaced the O ring and the area around the box is now oil free and by the way it was much easier to get to this box by removing the intake manifold and setting it aside. Plan on getting a new intake manifold gasket.

O.K....bought new "O" ring and plan on cleaning existing one but how the heck do you get it of the engine? I can't lift it high enough to get it out.

I did purchase a new intake manifold gasket just in case I had to remove that but do I? My intake isn't leaking so I thought I'd just try to get the oil separator off w/out removing intake but I'm starting to think I will have to remove it.

Any tips I need to know before I remove the intake manifold? It looks straight forward but want to check with you folks first.

Thx..

"...I can't lift it high enough to get it out..."

Be careful that the long tube that goes down into the crankcase is not sticking to the underside of the separator box and lifting up with it. IIRC, that thing is very tough to reinstall correctly if removed. You should only have to raise the box about - what? - less than an inch, to get it clear of the block.

You don't have to completely remove the intake manifold. Once unbolted, it can be pushed away from the head enough to give access. Just be very careful about the stress you're putting on fuel, vacuum, electrical lines and the throttle cable as you move it.
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Bob: Son's XC70, daughter's 940, my 81 and 83 240's, 89 745 (V8) and S90. Also '77 MGB and some old motorcycles