R80 Oil Pump Case Scoring

Discussion in 'Airheads' started by booysen, Apr 28, 2020.

  1. booysen

    booysen n00b

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    I'm in the process of rebuilding my 85' R80 and might have a bit of a problem after pulling the oil pump. There was quite a bit of scoring on the oil pump, which I will replace, but it also resulted in some scoring on the crankcase in the pump recess. It would be great if I could just ignore the scoring but I'm not naive enough to think that I can get away with that.

    Can anyone weigh in on how bad the scoring actually is? From my understanding, the two options for fixing this would be to get a new case or get a sleeve insert? What would the cost of the sleeve be? I would feel terrible about replacing a case because of wear on such a small area.

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    #1
  2. mars

    mars Starbucks anyone?

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    I had one like that and buffed it with a Scotchbrite type pad on a wheel and it looked fine and works fine too. I did put a new oil pump gear in. That is soft metal. I think these bikes have very robust oil pumps, you can measure the gap on your current gears to see if it is in spec.
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  3. ccmickelson

    ccmickelson MonoMania Supporter

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    I’ve recently pondered the same issue/question with an ‘86 R80. Per @bmwrench a sleeve or a new case are the only options but also may not even be necessary. A sleeve would require a complete tear down of the case and you’d have to find somebody that could do that sort of work. You could also reassemble and do an oil pressure test if in doubt if the pump's performance. Here's a link to a how-to if you choose to do a pressure test, including typical pressure values: https://brook.reams.me/bmw-motorcyc...diagnose-intermittent-low-oil-pressure-light/.

    I agree that these are very robust oil pumps, although not sure I'd remove any material on the I.D. of the pump housing in order to remove the scoring as you'd effectively be increasing the clearance there with the outer rotor.

    I’d also be wondering what caused that scoring. Metal from something was clearly pulled through there. Have you examined the lifters and cam lobes?
    #3
  4. Beemerguru

    Beemerguru Beemerguru...G/S guy

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    I've seen a lot worse that were still working just fine. Usually caused by someone forgetting to change the filter..or remembering about every 20K miles of dirt riding.
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  5. ME 109

    ME 109 Long timer

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    I’d be keen to see the main bearings, big ends and crank.
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  6. booysen

    booysen n00b

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    Thanks for feedback! Maybe a new oil pump would be good enough then, although I wonder how big of an effect leaving the scoring would have on the new pump's lifespan?

    Cam followers and the cam were all quite pitted so I'm assuming those went with the oil pump. There was a lot more wear on the cam lobes on the flywheel side, haven't thought too much about why that would be yet. The engine is mostly apart, just the crank is left but it looks ok from what I can tell.
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  7. bmwrench

    bmwrench Long timer Supporter

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    The lifter faces break up, which destroys the camshaft. All those sharp hard pieces are pulled through the pump, scoring it and the housing. The oil filter protects the crank bearings.

    Magnetic drain plugs begin to look like a good idea.
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  8. Beemerguru

    Beemerguru Beemerguru...G/S guy

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    Always wondered what the leading cause of the lifter failure?
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  9. robtg

    robtg Long timer

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    The fact that the airheads are 25 to50 years old may factor into it.
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  10. ccmickelson

    ccmickelson MonoMania Supporter

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    How many miles on it?
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  11. booysen

    booysen n00b

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    Not quite sure but as far as I know 60k+
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  12. ME 109

    ME 109 Long timer

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    My 81 rs cam and lifters are nearly 320,000 k’s old, and still look very good with no pitting.
    But then I do look after my engine.
    #12
  13. booysen

    booysen n00b

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    I bought this bike as a reason to get my hands dirty, didn't have much history on it and the guy I bought it from said it wasn't running when he started taking it apart. My plan is to get this oil pump situation figured out and then rebuild the rest of it properly. Unfortunately it needs a bit more maintenance than I had hoped but I guess thats how you learn.
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  14. ccmickelson

    ccmickelson MonoMania Supporter

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    Wrench has a theory about poor quality lifters in the mid-80's. He's got records of numerous low-miles mono's with lifter damage. The '86 sitting in my shed has less than 6K on the clock.

    The cam followers...

    8CA7F39D-B309-4DCC-B0E9-342B4951B33F.jpeg ED5CA192-3FA0-4175-9293-1464CC54549B.jpeg FBDB4B3A-A9DF-4632-AC5C-258FE4EA0AD0.jpeg

    And the resultant oil pump scoring...

    67CD6E54-6298-45F2-8566-B22DC819A2D1.jpeg 1381F6C1-B925-4995-87A1-D792882D27FD.jpeg 323CB903-039A-4F88-93C1-92FA92DE8909.jpeg 2AC625E1-996F-4330-AA7C-C2F9627C5B6D.jpeg 39A42EC1-BBCC-47DB-81F6-D9DA4149A17C.jpeg 7D5D9379-1FAA-499A-A67D-76D5510C5CF2.jpeg 17C3D775-2196-4F79-9AE2-887B3B5FD417.jpeg

    The cam had no discernible damage but I replaced it anyhow along with the lifters. Also replaced the oil pump components and all of the tolerances are well within spec and the pump is working great.
    #14
  15. AntonLargiader

    AntonLargiader Long timer

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    I dealt with the exact same thing maybe 5 or 6 years ago. Front bearing pin dropped out, bearing shifted, cam and follower destroyed each other, oil pump got trashed. '85 R80. I replaced the case.
    #15
  16. bmwrench

    bmwrench Long timer Supporter

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    I just heard of another one the other day.
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  17. Pokie

    Pokie Just plain Pokie.

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    Yes Virginia, lifters sometimes DO break-up.

    CrackedFollowers001.jpg

    Notice the crack on the bottom one, it's about to come apart. These were from a motor with about 50K miles. These were from a motor from 1972.
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  18. bmwrench

    bmwrench Long timer Supporter

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    That's why they changed to vertical lifter slots instead of the angled ones.
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  19. Pokie

    Pokie Just plain Pokie.

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    Maybe I should put those trashed lifters on Ebay, like those idiots trying to sell used oil filters!
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  20. booysen

    booysen n00b

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    Had a chance to pull the crank and get some pictures today. Main bearing carrier slid out easily which was nice and has luckily been the theme for most of the tear down.

    Crank seems to look ok to me but I'm not a trained eye yet. Also added some pictures of the oil pump and cam.

    Attached Files:

    #20