I have a 93 940 wagon that I recently bought with 177,000mi. It needed some work but only minor stuff. I replaced the water pump, exhaust manifold gaskets and other baic tune up things. I changed the oil and filter but I now have a oil leak. It drips from the back of the oil pan area where the transmission meets the motor.
Here is the mystery, it only leaks when I drive 15 miles or more. I let it run in my driveway up on ramps for thirty minutes and I get no leak. I drive it around the block and I get no leak. Today I drove it 30 mile to work and wala, puddle of oil. What is going on? I thought it might be the main seal but that would leak all the time not just after driving 15 plus miles. Whats my problem?
Thanks Gary

 

The seal might be old an only leak under hot and a pressure condition.
Is it turbo?

 

tech

It is not a turbo. Just to buy me some time would you advise any of the stop leak products on the market? What is involved in replacing the rear seal? Do I have to pull the motor? Drop the trany?
Thanks Gary

 

Could be a clogged flame trap ,building crankcase pressure and forcing oil out of the rear seal after it has been run for a while. Has the flame trap seen service?

 

You will have to remove the transmission to replace the rear main seal.
Yes I would also clean the Flame Trap as well.

 

I did find my flame trap and it is clogged. Can I buy this at Pep Boys or Auto Zone or is it the infamous dealer item?

 

Not 100% positive but I think you can.
If they don't have it try an Import specialist parts store.

 

It is an aftermarket part. If you can't find it locally, then all the online suppliers have it. If the flame trap disc was clogged, then there are two other parts that will need service. The part that the trap assembly attaches to, the plastic oil separator or pcv trap, and the brass nipple on the intake manifold were the small vacuum line from the trap gets it's idle vacuum. The separator can be somewhat of a bear to remove to properly clean. It is buried under the intake manifold at the ledge on the engine block, held down by two 13mm bolts. It can sometimes become brittle ( and the slip fitting on the engine) so you do not want to get brutal with it ( and have a hunk fall down in the oil pan), lift it directly up with no side pressure. Clean in mineral spirits, and replace the 34mmX3mm o-ring on the bottom ,or replace the whole thing if it is too far gone. The brass manifold fitting can be cleaned with a drill bit, or just remove and clean.

 

I bought the whole flame trap and insert and the problem is solved. I even replaced the small tube on the bottom of the trap because it cracked also. I will look for the other two pieces you mentioned but the leak has stopped. Thank you very much.