Hi Folks,

My 940 NA just started spewing oil out the rear seal.

Flame trap?

Breather box?

91k miles, so I'm hoping it is not the rear seal.

Any tips or suggestions?

Thanks.

Put oil in (1 quart low) and ran the car for awhile.

No visible leak.

BIG difference from the crazy leak before. It really was "spewing".

I'll keep an eye on it to see if any damage was done to the seal.

Thanks for the replies.

Nice that I have a "user serviceable" car and even had the parts on-hand.

New breather in.

Did not see an o-ring on the old breather. ???
Block surface where the breather sits was pretty dirty. Leaking?

Trap was clean but I replaced it anyway.

First short run showed no leak, but I need to put oil in, run it a bit and see what happens.

Seals will lose conformance and will continue to shrink including low mileage engines through the decades.
--
Beh.

I was chasing a high crank case pressure issue which made my rear main (and other engine seals) leak. Turns out that the rings were carboned up and stuck, allowing compression to blow past the rings, into the CC causing high CC pressure. Not sure how I figured this out but, I actually figured it out on my own. I remedied it by putting an ounce of marvel mystery oil(some use kerosene or ATF) in each spark plug hole, and leaving it for a few hours or over night to "un-stick" the rings. MMO may not be good for the catalytic converter but, it sure un-sticks the rings! And, as an added benefit, she ran like a scalded dog after the MMO treatment, easily feeling like it had about 20 more HP! On the bad side, I did at some point pulled the trans and put in a new rear main. You could try the MMO trick, and see if the leaks slow, or stop. Good luck brother!

Thanks for the responses.

I'll work on the breathers tomorrow and we'll see.

I am surprised by this because I take pretty good care of the car. ???

She's a gem at only 91k miles, so I'll do what I need to keep her on the road.

Dear Mr. Nabisco,

Hope you're well and stay so. If the rear main seal has been displaced, I suggest going to a transmission shop to get it replaced. They're used to pulling trannies and know that on Volvos, they have to mark the bolts - that secure the tranny's output flange to the driveshaft - so that the driveshaft remains balanced.

The job is not complicated but hard to do without a full-height lift and a transmission jack.

At the risk of laboring the obvious, I'd use a genuine Volvo seal (#6842160). It should cost about $35 at a US-based Volvo dealer. I'd supply the seal to the shop doing the work.

Hope this helps.

Yours faithfully,

Spook

If the rear seal has been dislodged, you usually can see the seal is out when you remove the aluminum brace bolted the back of the engine.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

I would begin by checking the flame trap. Build up there will allow crankcase pressure to increase and force oil out at the engine seals.

If you don’t have a new insert drilling each hole with the appropriate sized twist bit will open things up. Also check the hose that connects the flame trap nipple to the intake manifold. Make sure the nipple is open as well as the brass fitting that the hose is connected to.

You can check the oil separator box by attaching a piece of hose to the top and blowing into it (after removing the oil cap). Air should move through that without any resistance. They can be cleaned but that is not necessary if they are not restricted.

I always check the condition of the crankcase ventilation by removing the oil cap with the engine idling and holding a sheet of paper over the opening in the cam cover. There should be enough vacuum to hold the paper down over the opening.

If the flame trap or its associates are clogged or restricted the crankcase seals are under a lot of stress. This can actually dislodge the front or rear main seal and really spoil your day.
--
Any twenty minute job is just a broken bolt away from a three day ordeal

If oil is spewing out the rear as the OP said as opposed to weeping out at the bottom of the bell housing then I rather imagine the rear main seal is pushed out and his day is already spoiled. Often the front seals will push out first, but if they're in good and solid then the rear seal becomes the next weak link in the chain.

Lesson learned to others to keep your PCV system maintained. Much better news would have been the half moon plug at the rear of the valve cover blowing out which also results in oil spewing out the back. Regrettably for the OP, the 940 B230Fs have rear cam mounted distributors and there is no half moon plug, only the 240 B230Fs.

Either way, the OP needs to attend to the PCV system as you describe. One further note to the OP, when removing the flame trap the small nipple off the side for the little hose to the throttle body gets very brittle with age and easily breaks. Some people try to repair them with a mound of epoxy, but it's usually better to simply get a new one -aftermarket ones are commonly available as a kit with a flame trap element insert. They may not be quite as rugged as the Genuine Volvo flame traps, but they're usually quite adequate.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

When I had oil leaks every month,I followed Jim Bobbits advice,1 pint kerosene added to oil then I drove slow for 30 miles at 30 mph,,Darined oil left over night to get it oil changed to a new filter,Then I added 5 qts of synthetic,,& never had another leak for 6 mos..then just added about 1 pint.!!