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Question about transmission/oil leak

Discussion in 'Chevy Trucks' started by eamims, Jun 23, 2003.

  1. eamims

    eamims Junior Member
    Messages: 20

    Hi everybody. I have a small oil leak that I was trying to find and saw something I needed info on.

    Here's a photo of what I'm talking about: http://www.mimsarchitect.com/images/p1010069.jpg

    My question is: what is this? part of the transmission? There seems to be a drilled hole, then also what looks like a punched out or shot out hole, plus some bumps/protrusions here and there. Are these holes ok?

    My transmission oil stays at good levels, while my engine oil very slowly drops over time (i think I need to replace some gaskets). It seems to wind spread all the way back to the cross frame behind the tranny pan.

    As you can see in the photo...the oil drips on the muffler and creates that nice burnt oil smell.

    I couldn't find info on this part in my 1977 Chevy shop manual. It's a 1977 Chevy 350 C10 with a th350 tranny.
    Last edited: Jun 23, 2003
  2. wyldman

    wyldman Member
    Messages: 3,265

    That is the convertor inspection cover.The hole is there for a drain,or at least one of them is.Don't worry about the orher holes.If your getting oil out of that cover,it could be a rear main seal,the back of the oil pan,the convertor seal,or the front pump leaking.The first two would be engine oil,the latter would be trans fluid.

    I'd drop the cover,and clean it off inside,then start the truck and let it run (with the cover still off).You should then be able to determine if it's oil,or trans fluid,and where it's coming from (approx).Engine oil from the rear main,or oil pan would be on the froward side of the flexplate\convertor,and trans fluid from the pump or convertor seal would come down the back of the convertor.

    To drop the cover,you will need to remove the 4 3/8" bolts,and twist and wiggle it out of there.You may have to gently bend the trans cooler lines to make some room.

    If it's engine oil,then your going to have to drop the oil pan to do the pan gasket or rear main.If your going in,might as well do both.

    If it's trans fluid,then the tranny must come out to remove the convertor,so you can replace the convertor seal,and/or reseal the front pump.
  3. eamims

    eamims Junior Member
    Messages: 20

    Hi, thanks for the quick and detailed response. AFAIK, there is no oil leaking from these holes. I can't ride underneath the truck while driving (too bad, huh?) but I'm pretty sure the oil is being wind blown back to that point, and since it is a low point, it accumulates there and drips on or near the muffler. I need to get some engine cleaner and go to work on the whole thing and figure where the leak is coming from. I just noticed these holes and was unsure of their purpose, so I appreciate the info!

    I'm a newbie to all of this (well I completely replaced the body on my truck as well as the gas tank, but I'm new to engine/tranny work). Any ideas on a good/cheap way to lift the truck to work more comfortably under it? Ramps? Jacks?
  4. wyldman

    wyldman Member
    Messages: 3,265

    I'm not a big fan of ramps,as they tend to be unstable (the cheap ones).Get a set of decent jackstands,and use them.Only use blocks if they are good and strong,and won't slip or topple over with the truck on them.

    Get a can of engine degreaser (or a few),and clean it all off,so you can pinpoint the leaks.Then you'll know for sure.

    If the oil is blowing back,the it could be the oil pan gasket,or timing cover\front seal.

    These engines are also very bad for leaking at the rocker covers,and it runs down to the bottom.Try snugging them up,or replace them.Make sure you hammer the covers straight,and use load spreaders under the bolts.GM has the good quality load spreaders,or you can get by with the aftermarket chrome ones.
  5. 79Chevy

    79Chevy Junior Member
    Messages: 29

    I too have this problem

    Well not exactly.... I dont have any holes in any pans,
    You know where the stem goes into the transmisson so that you can pour trans fluid from under the hood...
    Well where the stem sits into my transmisson is where I am leaking my fluid....
    I am wondering if I could put some kind of sealant there to stop if from leaking or would that be a bad idea?????

  6. wyldman

    wyldman Member
    Messages: 3,265

    79 Chevy

    The dipstick tube is easy to fix.It is secured by one tranny bolt on the pass side.Remove the bolt,slide the dipstick up and out (leave it in the vehicle though),and pop in a new grommet.Slide the dipstick back in and your done.Most trans shops should have lots of grommets kicking around.

    It also could be your cooler lines leaking,and the fluid runs down in the area of the dipstick tube.Hose it off and run it until you can pinpoint the leak exactly.
  7. 79Chevy

    79Chevy Junior Member
    Messages: 29

    Thank you for the advice... will do....
  8. cj3859

    cj3859 Member
    Messages: 44

    maybe offbase?

    i had a leak that was driving me mad,couldnt find it for nothing,till someone told me to check my bleeder hole on my mechanical fuel pump,bingo! reason i'm sending this is cuz it looked the same way,blown back from down below, ps you'll need a mirror and flashlight,because its facing the block. good luck
  9. wyldman

    wyldman Member
    Messages: 3,265

    cj3859 - it is very possible that could be a cause of his leak.It's not one of the most common,but often overlooked.
  10. eamims

    eamims Junior Member
    Messages: 20

    I'll check it out...thanks. Tomorrow I'm cleaning up/painting my valve covers, changing gaskets, etc and also try to clean the rest of the truck so I can see what's happening better. I have a feeling it's coming from the cab side of the valve covers and dripping down, but I'd guess that no gaskets have ever been changed, so I may have some more to change out once I pinpoint it.

    Whats the best thing/solution to clean engine hoses with? Or should I just buy those flexi hose covers?
  11. wyldman

    wyldman Member
    Messages: 3,265

    Best thing for cleaning hoses id Spray Nine.Will cut the grease and grime,without attacking the hose.

    Don't forget to pound the valve cover surface flat around the bolt holes,so they don't leak.

  12. eamims

    eamims Junior Member
    Messages: 20

    Thanks, put them on yesterday, painted them a nice chevy blue. Anyways, I went to put them on and looked through my manuals and couldn't find a proper torque spec for the rocker cover. My 1977 Chevy service manual just said "torque to spec", but I couldn't find it in the book. Chilton's said, "3 Ft. Nm" whatever that is supposed to mean. I had also read on the internet somewhere 17 ft lb. 17 seemed too much, so I set them at 3 ft lb, but what is right?
  13. wyldman

    wyldman Member
    Messages: 3,265

    Just snug,or to where it just starts to compress the gasket.If they are overtight,you'll bend the cover,and crush the gaskets.Better too loose than to tight,as you can always snug them up a wee bit as the gaskets compress over time.