Oil Leak Question

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by 99Chevy, Feb 7, 2011.

  1. 99Chevy

    99Chevy New Member

    Ok, so my 99 4.3L V6 4x4 has a tiny oil leak. It's had it since I bought it and hasn't gotten any worse. I can park it and leave it overnight and I get one drop of oil on my driveway. It's pretty consistent anytime I leave it for more than a few hours I get a drop. I recently changed the oil and found a few drops on the rubber gromet where the transmission and engine meet. I cleaned off the bottom of the bellhousing/engine meeting place and drove it yesterday and today. I put it up on ramps today and didnt' see any leaks directly at the bottom of the bellhousing but I did find two drops of oil; one on the bellhousing and one on the rubber bushing. If you look up where the starter and such is it's pretty grimey but I would love to hear some thoughts on where this leak is coming from? I've heard some people say the distributor or valve cover gaskets?


    In the front of the engine if you look up above hte front differential inbetween the diff and sway bar you can see where some oil is/has been. Any thoughts if these two spots are related? Thanks!


    DAREDEVIL Rockstar 4 Years 1000 Posts

    more likeley the valvecover gasket...if it would be a tat farther back, could be intake gasket....but if its only a very small leak, dont mess with it if it is the intake...not worth it ..lol
  3. Patman

    Patman Rockstar

    I would really doubt the intake but valve cover is possible and distributor "o" ring. Let us know what you find.
  4. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Also oil pan gasket is possible. And the remote oil filter lines are know to leak.. Also the power steering lines are as well.
  5. 99Chevy

    99Chevy New Member

    So I started it today while up in the air and let it run till it was warmed up, cut it off and crawled under it. While under there I found a drop of oil leak out that hole between the motor and bellhousing near where the exposed bolt hole is. I guess this seals the fate as the rear main seal? Or could it be something else?
  6. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    99% chance its the rear main which is very common and nothing to really worry about if it drips a little since it is VERY time consuming to replace, and or expensive if you have a shop do it.. And there isnt always a 100% chance a new seal will get it buttoned up all the way anyhow. so id let it ride and just keep an eye on it.
  7. stephan

    stephan Rockstar 4 Years 5000 Posts

    Hey 99, see how far up you can trace this leak. The origin could be up high & running down between the engine & trans mating surfaces & then down the back of the block making you think it's the rear main seal. I found one like this that was the rear intake seal like Scott said. They don't/didn't make gaskets for the front or rear of the mani & just put silicone sealer on them & it didn't last. Crawl in your engine bay & feel around the back of the manifold & see if it's wet.

    *I had one that I thought was the oil press switch, so I put some pipe thread tape on it, (didn't fix it) put a new distributor gasket on it, (didn't fix it) finally found a pin hole leak in the silicone at the rear of the mani.
    Last edited: Feb 12, 2011
  8. conroe

    conroe Member

    PVC valve rubber gasket?
  9. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    My Suburban-1998- has a small leak in that general area.
    I just check the oil every week and keep an eye on the gauge.
    As nearly as I can tell it is less than one ounce every few days-maybe a quart every couple of months.

    I'm living with it.If it was a newer vehicle and didn't have 215,500 miles on it maybe I would get worked up about it.No point in spending much time chasing down a leak when any-day the motor might croak. It runs great now- 20 mpg hy-so it is a good motor, but 215,000 miles is a lot of miles. It gets me to work so all is well for now.

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