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Thread: Time for new motor??

  1. #1
    Join Date
    Feb 2006
    Posts
    23

    Default Time for new motor??

    1992 BMW 525i -- Auto -- 101,000 miles -- M50

    Got back from vacation and went to start the bimmer and it would start. Just cranked and tried to catch every once in awhile but that's all it would do.

    Pulled plugs and they are all wet so it's getting fuel.

    No codes stored.

    Checked coils and they are each hot and each plug has spark.\

    Checked timing chain and tensioners. All seem ok and cams are in proper position.

    Did compression test dry:
    #1=50 / #2=80 / #3=75 / #4=40 / #5=0 / #6=100

    Did compression test wet:
    #1= 100 / #2=125 / #3=160 / #4=100 / #5=50 / #6=100

    Did leakdown test:
    #1= 80% / #2=40% / #3=40% / #4=65% / #5=75% / #6=25%

    What do you think?

  2. #2
    Join Date
    Jan 2004
    Posts
    4,150

    Default This seems pretty common with the m50 , squirt some more

    oil in the cylinders like you did for the wet test and try starting it again. Some peoples m50's seem to lose the ring seal when setting for awhile. Once you get it to start if you check the compression again you'll find out that its fine. Squirt oil into cylinders and crank for a short while with the gas pedal to the floor , then crank normally and you should be able to get it to start.




    Quote Originally Posted by JScritch
    1992 BMW 525i -- Auto -- 101,000 miles -- M50

    Got back from vacation and went to start the bimmer and it would start. Just cranked and tried to catch every once in awhile but that's all it would do.

    Pulled plugs and they are all wet so it's getting fuel.

    No codes stored.

    Checked coils and they are each hot and each plug has spark.\

    Checked timing chain and tensioners. All seem ok and cams are in proper position.

    Did compression test dry:
    #1=50 / #2=80 / #3=75 / #4=40 / #5=0 / #6=100

    Did compression test wet:
    #1= 100 / #2=125 / #3=160 / #4=100 / #5=50 / #6=100

    Did leakdown test:
    #1= 80% / #2=40% / #3=40% / #4=65% / #5=75% / #6=25%

    What do you think?


  3. #3
    Join Date
    Mar 2006
    Location
    USA
    Posts
    1,839

    Default

    the ring seal can be "slowly" fixed by adding lots of molydenum disulfide to the oil, as it bonds with the metal under pressure. you will probably need 10000 miles before compression is back to spec.
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