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Rear main seal leakage - should I use a stop leak? [1994 IDI w/ turbo]

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Andrew Sang, Sep 8, 2020.

  1. G. Mann

    G. Mann Full Access Member

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    I just scrolled through the entire thread and I'm surprised that everyone has overlooked another leak source coming from the same area as the rear main seal...
    That is the flywheel bolts.
    The flywheel bolt threads go through the crank flange. If the bolts are installed without thread sealant, oil will migrate past the threads and act like a real seal leak.

    In any case, spray the entire engine down with something like Foamy Engine Cleaner [I like it because it dissolves oil and sludge quickly] then hit it with a car wash pressure nozzle to clear off all the oil you can...
    Pull the lower flywheel cover [4 bolts, if they are all still there] and run the engine for a bit. use a good flashlight and look up at the flywheel/block area for fresh oil drip..

    In either case, main seal or flywheel bolts... both are going to come out and be re-sealed..
    Good luck.
     
    Tim McKay and Blackascoal like this.
  2. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    I'm not sure if the flywheel bolts would leak this much or not. I've never seen an engine without sealer on those bolts.
     
    Blackascoal likes this.
  3. G. Mann

    G. Mann Full Access Member

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    In either case, the flywheel bolts must be removed to access the rear main seal. Transmission removal, flywheel removal, has to happen.
    While you are in there, take a good look at the freeze plug that lives behind the flywheel also. In and out once, so you don't have to go back for a long time. Seal up the bolts while you are putting it back together.
     
    Tim McKay likes this.
  4. Black dawg

    Black dawg Registered User

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    I have seen plenty with no sealer, and they do have some oil weep out to the bolt head, just enough to look slightly oily around the bolts...…..if they are tight.
     

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