Oil leak, but not where I thought the leak was

[delta_p]

I pulled my transmission thinking the crank shaft seal was leaking. But when I got to it it looked like it is dry and it is the oil pan gasket? It is a little wet up top the engine too but I can't tell if it is from this. I swear the seal looks good, I attached some photos.

Would you even replace the seal? My truck is a 96 C1500 with 162K miles.

I am going to change the oil pan gasket. Should i use the FelPro blue gasket or is there a better option? Thanks for any input.

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[Blanco_obs]

I had the same issue. Turned out my oil pan had a pin hole rust spot on it. Found that out after I replaced everything and added oil


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[Supercharged111]

I'd still do the rear main. The 2 leakers that I have replaced didn't really look like they were leaking. The way the oil gets slung all around, most of the time it's a thin coat. I thought the oil sender was leaking on my Camaro, but it was the rear main slinging oil out a hole just above it.

 

[evilunclegrimace]

I would bet that the intake gasket is leaking. The rear main is not leaking BUT, since you are this far into it would not be a bad idea to change the rear main now while it is apart

 

[delta_p]

Thanks guys. I guess I will go ahead and put the rear seal in. Any tips on the oil pan gasket. looks like the pan should have plenty of room to come out with the back end off the engine.

Looks like i need to check out intake gasket too.

 

[Supercharged111]

Pretty sure pan on a 2wd just comes right out

 

[Schurkey]

"I" would spend time with a leak-detection aid.

Fancy ones are a fluorescent dye in the oil, UV light, and special glasses. You might be able to rent the equipment, and buy dye at a local parts store using their "rent-a-tool" program.

Cheap leak detection is a can of baby powder AFTER you've cleaned the existing mess up with hot water and laundry detergent. Blow it dry with compressed air when it's completely oil-free.

Run the engine for half-an-hour or an hour, look for fluorescent oil or see where the baby powder sticks.

Be damned sure you don't have a leak at the oil filter that's drooling down the pan. You don't want to replace the rear main and the pan gasket when the oil filter needed another third of a turn.



P.S. What's holding the engine up in back? Have you already bashed the distributor cap on the firewall?

 

[delta_p]

Hey Schurkey thanks for asking that. I had a piece of 2x4 jacked on the starter housing but I had to move the jack for a minute and I check the back of the engine when I did that. nothing hit. But i forgot to add it back until you just said that, thanks.

 

[swaz]

Sometimes the oil cooler line or the oil filter housing has a leak that rolls on back to the back of pan looking like a rear main seal leak too. Clean the filter housing area well and check after driving around for a bit . Common issue . Some people remove oil cooler lines but not necessarily best option. Oil filter housing leaks sometimes too orings .... but most times I’ve experienced cooler line where they connect into housing is the issue . Looks like a main seal leak ....

 

[bobby v]

"I" would spend time with a leak-detection aid.

Fancy ones are a fluorescent dye in the oil, UV light, and special glasses. You might be able to rent the equipment, and buy dye at a local parts store using their "rent-a-tool" program.

Cheap leak detection is a can of baby powder AFTER you've cleaned the existing mess up with hot water and laundry detergent. Blow it dry with compressed air when it's completely oil-free.

Run the engine for half-an-hour or an hour, look for fluorescent oil or see where the baby powder sticks.

Be damned sure you don't have a leak at the oil filter that's drooling down the pan. You don't want to replace the rear main and the pan gasket when the oil filter needed another third of a turn.



P.S. What's holding the engine up in back? Have you already bashed the distributor cap on the firewall?

I had a leak down there that defied logic, they replaced the pan gasket, and tried everything they could think of short of replacing the rear main seal. So being such a shade tree guy I thought Il get under there for a look see, nothing. Let it go for a while but leaks REALLY bug me. even went so far as to buy that Blue Devil Rear main sealer as I thought it had to be that seal. But I kept checking and it turned out to be that someone has painted the block before I had the truck and they got paint on the sealing rim of the block where the filter seats, and it was coming off in places, cleaned it real good and no more leak.
Also had the tailshaft seal keep leaking, finally figured out it was the drive shaft was too long ( from being lowered I guess) so shortened it and put new seal, no more leak. Sometimes its weird stuff like that
Bobby V