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'00 300m intake plenum valve cover spark plug tube seal questions

Discussion in 'LH: Large Cars, 1993-2004' started by MoPar~Man, May 29, 2017.

  1. MoPar~Man

    MoPar~Man Member

    Jul 9, 2014
    I picked up the following from rock auto because they were either really cheap or dealer close-outs:

    valvestem seals (12 pieces)
    Federal Mogul / Fel-Pro SS 72842

    Plenum Gasket (1 piece)
    Victor Reinz / Mahle MS16508

    Intake Manifold Gasket (2 pieces)
    Victor Reinz MS16210

    Valve Cover Gasket (2 pieces)
    Victor Reinz VS50248

    Valve cover grommets (12 pieces)
    ROL Gaskets MM23506

    I understand that if I'm seeing oil on the spark plugs when I take them out, that it's probably because of leaking spark-plug tube seals. Also, am I correct that some of the above items might be time to replace anyways?

    I don't have the tube seals yet, but I'm wondering, before I attack the engine and start taking this stuff apart, do I have everything? Should I get any other seals / gaskets or do-dads and have them ready to swap in as I'm taking all that stuff apart?

    And about the valve stem seals - what kind of job is that? Any special tools needed?

    I do have the FSM (as a set of PDF files, including engine) but haven't looked at it yet (for this project anyways).
  2. Tomguy

    Tomguy Well-Known Member

    Oct 4, 2011
    You need 24 valve stem seals, 12 per side. I've had my manifold off at least 4 times, and re-used the original plenum gasket; I have 210k miles on mine. Not saying it's not a good idea to replace it if you think it's bad, but just mine is fine with always torquing it back to spec in the proper torque order. As for the valve covers, I think there are 8 needed per side, not 6 or 12.

    If you're doing valve stem seals, you'll need a tool to adapt your air compressor to your spark plug hole, so the compressed air can keep the valves closed. You'll need to remove the rocker assembly and then use a spring compressor to get the springs off, to do the seals. The rocker assemblies are known to fail over time and cause "The 3.5 tick" - later models have a revised assembly that's less likely to snap the dowel pin(s) and thus cause it.
    Edit: I would suggest moving each cylinder to BDC so the compressed air doesn't "Push" it down and thus causing a pressure loss that drops a valve on you. Then the heads will have to come off.

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