Oil leak behind pan

[krinkov58]

I just bought a 1996 Legacy for my wife as a beater but hope to make it last a while. There is an oil leak behind the oil pan that has gotten progressively worse over the last month. No coolant in the oil, nothing leaking from the front. Not sure how much of the oil is blowback. I'm hoping for the pan gasket to be the problem but have the feeling it's something a little more sinister. Any ideas/prophecies of impending doom?

[Platinum_Racing]

It could be the rear main seal on the engine or the oil pan gasket, but from that pic it looks like the leak is coming from elsewhere. The reddish tint to the oil could just be the camera, but it could also be transmission fluid.

 

Can you take another pic or two just for clarification? Maybe a pic from underneath the car, facing the camera up at the back of the oilpan.

 

Also, is this car a manual or automatic? That would tell us if that even has the potential to be ATF or not. If the fluid on the ground is red, it's ATF.

 

 

The sad part is if this is the rear main seal it's gonna take more time than money. If you did it yourself with the proper tools you're looking at time to get the motor out and put it back in, all for a cheap ass part. If it's the pan gasket you should be able to tell. Either way, the pan gasket isn't exactly a picnic. I've never replaced one on a Subaru, but I've heard that things get in the way of removing it completely. If you can get the pan lowered enough to get all the old gasket material off then you're in good shape, just be careful none gets into the pan when you're scraping at it.

 

First thing I would do if its oil is do an oil change and fill the engine with the correct amount of oil. Overfilling the crankcase with oil can sometimes blow out the rear main seal prematurely. If there's too much oil, it can leak out.

 

 

 

 

The good news is even if its the pan gasket or the main seal, if you keep oil in the engine there's nothing to worry about as far as durability. Just check the oil every couple of days until you know how fast it leaks then add more as needed until you can replace the gasket or seal.

[krinkov58]

2 more photos...degreased the surrounding area in these. It's an auto but it's not ATF that's leaking.

After degreasing, the crossmember and oil pan in the first photo are still devoid of oil even though it's been a while. Not visible is that on the plate in the 2nd photo, oil has already begun to seep through the rearward 4 holes and is dripping on the ground. Don't know how the oil could make it that far back if it was a pan gasket and the car was stationary. So perhaps the rear main seal? I could pull the engine but it seems like a lot of work for a car that's meant to be temporary. It'll just get banished from the car port.

Additionally the car really stumbles off idle and at low rpms, and the check engine light comes on and off at random. I usually work with carburated cars and know next to nothing about EFI, but what would that be? Spark advance? Some O2 or air flow sensor somewhere?

[Platinum_Racing]

Usually its just the spark plugs and wires will make the car stumble and misfire, especially off idle. Replace these as well as the air filter and maybe the fuel filter and you should be good to go.

 

 

As far as regular maintenance to maintain a steady idle:

There is also an Idle Air Control Solenoid to the left of the throttle body, slightly under the intake manifold. If you want to remove the hose off the IAC that leads to the intake tube you can have a friend start the car while you spray some O2 sensor safe carb cleaner into the hose. You should let the car die out a couple times and rev it a little bit. Without the hose it will die shortly after its started. This is normal and expected. The car will idle normally once you put the hose back on. Its the only way to clean the solenoid without removing it, and it usually yields good results.

[rubberman]

Sounds like the rear main seal is the leak issue to me as well. Platinum is right, it's a lot of labor for a simple fix with that seal although removing that engine isn't as bad as the newer LGT's.

For the oil pan alone - you can lift the motor up some off the crossmember with a hoist and pull the oil pan. It's a little tight on the rear-most oil pan bolts but it's doable. Cleaning the old liquid gasket off the flanges is what takes a while (both the engine flange & oil pan). I like to use a plastic paint scraper, cheap and won't scratch the aluminum surfaces. Brake cleaner strips everything down well and removes any trace oil residue so that the new liquid gasket material can bond well.

 

That said, if you pull the motor then both the rear main seal and oil pan are far easier to do on an engine stand. Also, if the motor is pulled, then you might consider the need for timing belt, cam seals, water pump, pulleys, etc since those may need to be replaced. Just things to think about, good luck with the repair! Subaru service manuals in pdf form are on the web that explain all the steps to do these repairs.