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Thread: Mack rear main seal install tool

  1. #1
    Supporting Member Frank S's Avatar
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    Aug 2015
    Peacock TX
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    Frank S's Tools

    Mack rear main seal install tool

    One of the pitfalls of being away from mechanic work for a number of years is a lot of the old tools I used to have I have to remake before I can finish a job.
    I know a lot of guys might try to install the delicate rear main seals by just using a punch and a hammer but I never have done it that way and am not about to start now.
    a few years ago I sawed up several thick disks from a large diameter piece of round stock. Yesterday I machined one of these to be a seal install tool
    Mack rear main seal install tool-20180621_152651.jpggg.jpg
    Since I had the flywheel housing off and knew before hand the depth the seal needed to be driven I installed it before reinstalling the housing.
    Note to mechanics, #1 Not all flywheel housings can be removed without dropping the oil pan.
    #2 most seals installed at the factory are not driven all the way in even on housings that have a flange stop. the reason for this is so future replacements the seal can be located on virgin surfaces by setting them deeper.
    Machinist note if making an install tool for someone you need to #1 have the seal to take your measurements from and #2 you need a reference depth that the original seal was installed from the end of the crankshaft. As a general rule this will be in the range of .375 to .437 for the Mack E7 engines. when bottomed out against the flange this is going to be around .575 to .625 A hole must also be drilled to match the flywheel locator dowel if the tool is to be used on a housing while it is mounted to the engine.
    The best way to insure a seal is installed true and square to the crankshaft is to leave a center boss to the bore this will set the depth and shims may be used for restricting the depth when the tool bottoms out against the crankshaft all the way around the seal will be at proper depth true and square
    Mechanics sub note All new crankshaft seals now come with a plastic install guide ring that will fit over the shaft diameter spray a thin lube on the seal to allow it to slip over the bulge in the plastic tool this will prevent damage to the seal. Of course the obvious is to make sure the shaft is clean by using a fine grit emery cloth make sure there is no remaining parts of the old seal sticking to the shaft.
    Mack rear main seal install tool-20180622_180510.jpgcc.jpg
    installed and ready for the flywheel
    Mack rear main seal install tool-20180622_184007.jpgcc.jpg

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  2. The Following 4 Users Say Thank You to Frank S For This Useful Post:

    NortonDommi (Jun 25, 2018), PJs (Jun 26, 2018), Seedtick (Jun 25, 2018), Toolmaker51 (Jun 25, 2018)

  3. #2
    Content Editor
    Supporting Member
    DIYer's Avatar
    Join Date
    Aug 2013
    Thanked 1,587 Times in 1,423 Posts

    Thanks Frank S! We've added your Seal Install Tool to our Transmission category,
    as well as to your builder page: Frank S's Homemade Tools. Your receipt:

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