Well, my newly acquired '93 960 wagon has developed a rear main seal leak sometime between last week when I picked it up and this weekend when I changed my trans fluid and filter. I checked this area before I bought the thing, and it was as dry as a bone, but now it leaves a 4" round spot of oil everywhere I park it. It's definitely coming from the plastic inspection cover on the bottom of the bell housing.

On the bright side, my transmission is acting much better now.

So, can anyone direct me to a good 960-specific write-up for replacement of this little bugger? Any tips, or special tools I would need? Any advice is greatly appreciated.

 

Is it transmission fluid or engine oil? It is not uncommon for some pan bolts to be leaking after changing the filter. There is a certain pattern of tightening pans in these transmissions, plus a certain Tightening torque. Here are the 960's Documents -- this info should be there...

 

It's definitely oil. I noticed it before I started the trans service.

I got more good news, too. I took the wheels to get them balanced, and found that one rim is bent. I guess that explains the vibration.

 

You should check the front and rear cam seals too. You should service the PCV, which is probably the cause of these leaks.

 

Aha! Now we're getting somewhere. I checked the flame trap as soon as I got the car home, but I didn't know about the PCV box until I looked it up this morning. Looks like that will be my next project. Hopefully that will at least slow down the leak enough to make it driveable.

Thanks Henry. I really appreciate the help. I may be a slow learner, but I'm gettin' there.

 

The 960 does not have a PCV box does it?

 

I don't know, but I found these instructions on the brickboard FAQ:

B6304 Engines: [John Roberson]
Disconnect your battery negative. You will need to get a 3/4 adaptor for your socket wrench to take the pressure off your serpintine belt tensioner. With the tension off the belt tensioner, take a small nail and insert it in the hole to fix the tensioner. Now remove the two bolts holding the tensioner from its holding brackets. With the belt and tensioner out of the way, remove the bolts holding your power steering pump and move the pump out of your way your right out of the way, fixing it with a cord to hold it. Next remove your alternator bolts from their brackets and disconnect the two wires from the alternator well. Remove two plates affixed to the block. Remove two 10mm bolts on each side of the oil breather box. Pry off hoses using a blunt screwdriver and inspect them for plugging or deposits. Remove the box. Clean the box and make sure the drain into the sump is clear. Replace everything, using Vaseline as a lubricant to help things go back together.

B6304 Seal Replacement Notes. [Inquiry] The new seals I bought for my breather box look nothing like the old ones. [Response: Walt Poluszny] The new green doughnut goes on the side against the block with the flat side of the doughnut facing the PCV box. The old bottom/right seal against the block was indeed a tube with two hose clamps. The new upgraded part (P/N 8653339) is rubber with a metal fill sleeve. The 'flanged' end of the tube goes toward the PCV box. I used RTV as a lubricant and a sealer on the 'O' ring and tube on the advice of a Volvo mechanic.

 

Breather Box or technical term is Oil Separator.


There are 4 holes (outlets/inlets) into the Breather Box (Oil Separator). Any or all four can be clogged. Be especially careful with the bottom one, which you can't see without removing the Breather Box. If you push it in, it can drop into the pan, which means you will need to remove the pan to take it out, which means you need to remove the subframe or lift the engine to take out the pan. All doable, but you can create a lot more work than you need to.

On accessing the Breather Box: Brickboard describes one way. The other way is by taking the Intake Bowl, very similar to 850's procedure. I have done both and prefer taking out the intake bowl. The other way, I had trouble taking out the engine bracket at the rear of the alternator/compressor.

If you go the intake route, make sure you also get a new $ 7 intake gasket. You also need to know about the hidden bolt, there is a photo and description in the Google documents I linked with.

 

All right, I got the breather box out this morning, and it is clean as a whistle. No blockage anywhere.

I don't know if I should be happy that my engine is so clean inside, or disappointed that I didn't find the cause of the problem.

So, is there anything else that could be clogged that would cause excess crankcase pressure, or is this just an old-fashioned seal failure?

I know the car hasn't been driven much in the last couple of years. So I'm thinking maybe the seal had dried out but hadn't started leaking yet when I looked at it, and then my 150 mile trip home at 70ish mph was too much for it, and it gave up the ghost.

 

I am assuming that there is no blockage in any of the 4 lines to the Breather box, and the vacuum tree is not clogged. The dry seal possibility is plausible, but it have it seen it more on the transmission seals when sitting a long time.

Did you check for any leaks at the front crankshaft seal, and also both front and rear camshaft seals?

Any possibility that the leak is coming from the pan?

 

OK, I'm finally getting a chance to play with my cars again. Been working a ton of overtime since Hurricane Irene hit.

So, anyway, all the cam seals and the front crank seal are dry. There is some minor seepage from the oil pan gasket, but nothing to speak of.

As far as I can tell, it doesn't leak while the car is running. Well, it doesn't drip anyway. Maybe it's collecting up in the bellhousing and dripping out after shutdown?

I've only had to add a half quart of oil in about 500 miles, so it's really not that bad yet. I think I'm just going to drive it for a while and work out the other bugs, and maybe in the spring I'll see if I have the gumption to tackle the seal, or I'll wuss out and pay a shop to do it. I'm getting too old to lay on my back in the driveway for hours at a time. I got a quote of $580 for parts and labor from the dealership, and there's a good independent shop nearby that I'm sure would do it for less.

I really appreciate your help Henry, and those "documents" will definitely come in handy many times down the road. Thanks a million.