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1985 GMC S-15 Dillema....Need help

Discussion in 'General Chevy & GM Tech Questions' started by b717doc, Mar 4, 2014.

  1. b717doc

    b717doc New Member

    My 1985 GMC S-15 pick-up is in MINT condition, and I really love that little truck, but it has become a HUGE problem for me....It has a recently re-built (15k miles) 2.8 liter V-6 in it, that started leaking oil from the weep hole in the torque converter cover. I pulled the transmission, which was rebuilt at the same time, and could not find any way to replace the rear main seal from the back of the engine. I bought a "Chilton's" book for the truck, and it says to remove the engine, #4 bearing cap, and the oil pump to replace the 2 piece rear main seal. We rented a cherry picker, and borrowed an engine stand, and pulled the engine last weekend...replaced the rear main seal, oil pan gasket, intake gaskets, and both valve cover gaskets.. We put the engine back in, and I've got her running pretty good, but the oil is REALLY pissing out now, from the same weep hole....Just very frustrated with the thing now, and not sure what to do with it.....Im hearing that a 4.3 liter V-6 is an ideal replacement engine, but not sure if my transmission will mount up to a 4.3...
    Will I have to have another transmission as well? OR, should I just pull the engine again, and try another seal? I AM sure the oil is coming from there, as it is dry from the torque converter up, and the cover was FULL of oil....Im thinking if I pull it, I may as well put a better, stronger engine in there....STILL beats a new truck payment! ANYONE know where I can get a good 4.3 V6 in the Atlanta Georgia area?
  2. silverado002

    silverado002 Member 100 Posts

    I can give you some thoughts I have. Did you put the seal in backwards? If it has a lip on it I believe that lip faces forward. (Don't quote me on that one as its been a few years since I did one of these.) Also a small dab of sealer on the seal ends at the split and on the corners/mating surfaces of the main bearing cap? Did you check the rear cam plug and oil annulus plugs if they are tight and not leaking? How about the oil pressure sender? If its in the rear top it could do that too. My best thoughts on it. Don't know if this helps.
  3. zuki82

    zuki82 Member 1 Year 100 Posts

    Ditto what he said! Are you sure its not tranny fluid? Front tranny seal may be leaking? more so now that you took out the tq converter again!
  4. b717doc

    b717doc New Member

    Definitely engine oil....and ALOT of it...I found a shop that says they will "pin-point" the source of the leak for me, then I could go from there...Truck sat there for 3 days before I got a call from him, saying the the oil "seemed" to be coming from the oil filter housing, and "possibly" some other areas....I didn't want "possibly", the agreement was "exactly" where it's coming from...after a small argument, I told him Im coming after it tomorrow...$85 for NOTHING....
    He's convinced the oil is coming off the oil filter housing, streaming back on a "ridge", and filling the torque converter cover with oil....I call BS....says the "smoke check" (whatever that is) did not reveal leakage from the rear main seal... At this point, I will fix the leak at the oil filter housing and go from there.....NO MORE SHOPS
  5. silverado002

    silverado002 Member 100 Posts

    I don't know if this will help but I learned from fixya (website) that in 1985 there were 2 rear main seals for the 2.8L. first design is 5.5mm thick. Second design is 11mm thick. When you replaced that rear seal did the old and new look to be the same thickness?
    Also is there any way to view the back of the engine through a cover of some kind? I've heard of a chemical dye that can be added to the oil that is fluorescent and can be see with a ultraviolet light to aid in diagnosis.
  6. zuki82

    zuki82 Member 1 Year 100 Posts

    with out pics, its very hard to help out! It is possible that hes right! A good washing and then a die test will show for sure!

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