new oil leak

[GregCrabb]

Hey all, my truck sat much of the winter and now I'm driving it more, I have noticed a "new" oil leak. I can't tell where it's coming from yet, I just noticed oil is being thrown up onto the tailgate, it's never done this before. I can't find anything "pouring" out of it while running. I'm suspicious of the rear main seal, I've looked on here and read it is possible for me to change it without dropping the trans. My local diesel shop wanted at least $500 to change the seal, but they were talking of dropping the trans too. You'd think they would know it can be done without dropping. I cleaned the engine today with solvent cleaner to see if I can locate the source of the leak, I don't see anything from above. Could valve cover gaskets leak bad enough to throw oil up onto the tailgate? Oil lines are all OK. I'm bummed out, i don't want to get rid of my trusted friend of 8 years but don't want to have to drop a lot of money into it either. It runs without a hitch, good power and compression (400# all cyls). Advice? It's an '86 with a "C" engine but "J" intake.
Thanks

[john8662]

Don't dismiss the vacuum pump, they can go to leaking out the pod and make a good sized messed that looks like a rear main seal.

Just something to check.

J

[GregCrabb]

I crawled on top of the engine and looked down on the pump but couldn't see any oil there, will look more closely. Drove the truck tonight and looked under it, definitely something going on in the rear, new oil drips hanging at the back, didn't see any new evidence at the front since degreasing last week. It runs so good I hate to think of parting with it...although a small SUV or quad cab S-10 type truck would be nice...just not diesel powered.

[john8662]

Rear main seal, and the rear pan seal and RTV holding the pan to the engine. They can and do leak, it's a job for sure, you'll need a clean shop space and an engine hoist to complete this task.

J

[GregCrabb]

I can confirm it is not the vacuum pump leaking. I drove the truck about 60 miles yesterday and parked it overnight. Looked around under the hood and under the truck today. It sure appears it's coming from the back of the engine where I can't see. I don't think the valve cover gaskets are leaking THAT bad although they are leaking a bit...I see some new oil around the fuel lift pump but not that much and certainly not enough to cause this massive undercoating. I replaced the CDR valve with the IP 24,000 miles ago just for the heck of it. This is coating the underside of my truck! I don't drive it much anyway so it can wait until I find more information on here (and advice). I'll just have to keep a closer watch on the dipstick :-) when I'm driving more than a 100 mile round trip to work and back which is only occasionally...the diesel Volkswagen is so much more economical right now. Thanks for looking and answering. The engine is running better than it ever has it seems...go figure.

[GregCrabb]

I'll probably tackle the rear main seal myself. Do you think I should go ahead and replace the oil pump while I'm in there, it has 200k miles on it and it's only like $32 from Advance Auto. Will probably do the valve covers as well while I'm all black and greasy...I dread this, but I'm cheaper than anyone else is.

[HH]

Are you sure it is oil, and not a fuel line leaking into the valley?

[GregCrabb]

valley is dry as a bone, already been down the fuel leaking in the valley of the shadow of the intake manifold road. It's oil, showing up on the dipstick...one quart out of a hundred miles....that is significantly different from my usual one quart out of 3000 miles....