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1987 m20b25 burning oil

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    #1

    1987 m20b25 burning oil

    So I have an older m20b25 engine (miles unknown but burning oil so assuming older) in my 1985 318i and like all old engines eventually do, mine has started to burn oil. First thought was that the piston rings were shot and didn’t realize what kind of job that was to replace so I called a local shop and asked for a quote..... long story short, the mechanic told me that customarily, bmw pistons/rings are bulletproof and then when your engine starts to burn oil, it’s the valve stem seals that need to be replaced, not the rings. I’m not sure if he was assuming that I had a newer car and was talking about newer engines or that that holds true for all ages. Is that the case also with my engine? I do realize that the engine is old so very well could be the rings as well but if anyone has been through a similar situation or knows anything about that, would love to hear back.


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    #2
    Doing a leakdown test may help you to pinpoint whether it's the top or bottom end, but that may not matter if you're burning oil. You might be at the point of rebuilding the engine or swapping in a different m20.

    Now might be a good time to get a cheap m20 to rebuild for when yours lets go.
    sigpic
    1987 - 325i Convertible Delphin Auto [SOLD], 325i Convertible Delphin Manual [SOLD]
    1989 - 325i Convertible Bronzit m30b35 swapped [SCRAPPED], 325i Sedan Alpine Auto[DD]
    1991 - 325i Coupe Laguna Manual [Project], 535i Sedan Alpine [SCRAPPED]

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      #3
      I agree with the engine rebuilder. The valve seals are usually the culprit.
      I had an 86 325es (2.7) and despite religious oil changes, it started to use a little oil.
      After changing the valve seals, all was fine.
      If it's got tits or tires, it's gonna cost ya!

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        #4
        You've got good input above. Before you spend a dime on repairs you need to have full diagnostics done..ie compression and leak down tests. Your mechanic seems familiar with our cars so he'd be the guy to discuss this with.
        Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

        https://www.r3vlimited.com/board/sho...86#post4944786
        Alice the Time Capsule
        http://www.r3vlimited.com/board/showthread.php?t=360504
        87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

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          #5
          Great feedback, thanks guys


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            #6
            General Discussion is not a catch-all; please do not ask technical questions there. If you don't know where to ask your question, post it in General Technical and we'll move it to the appropriate subforum if necessary. Thanks in advance.
            Originally posted by kronus
            would be in depending on tip slant and tube size

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              #7
              Slight thread jack, does anybody have a view on who makes the best valve stem seals.
              I have a set of Reinz seals but I'm wondering if there are better options.


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