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Thread: '83 R65 Oil leak. Transmission input seal and/or main seal

  1. #1
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    '83 R65 Oil leak. Transmission input seal and/or main seal

    This is a 1983 R65 with 12,000 miles. It sat for years before I purchased it. All the external rubber was shot. I imagine many of the internal seals are bad as well.

    I will probably replace:

    Flywheel O-ring.
    Rear main seal.
    Oil pump O-ring.
    Gearbox input seal.

    - as recommended by Ted Porter.

    But I wonder if anyone has a best guess of the source of the leak. My guess is that it's the transmission seal from what I can see in the photos, but due diligence is going to make extra work for me and make me replace the lot.

    Any opinions?
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  2. #2
    Registered User toooldtocare's Avatar
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    Pretty much looks like the inside of my 78 R100RS. Ruined the clutch too. It was the rear mail engine seal, but I replaced everything just to be sure. I think that is the only safe thing to do, with that much oil.

  3. #3
    Administrator 20774's Avatar
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    Welcome to the forum! A fun project to take on.

    Three of the four items that Ted recommended to replace are on the currently covered side of the flywheel. It does look like the tranny input seal is a culprit, but if this thing sat that long, you can bet the other seals are not far behind. It's hard to tell from the picture, but once you get the flywheel/clutch carrier off, you will see if the other areas behind it are also leaking. The transmission would leak gear oil...the engine side would have leaked engine oil...probably hard to tell the difference at this point.

    If you've never removed an Airhead flywheel before, it's very important that you block the crankshaft on the forward side of the block before you begin to remove the flywheel. Failure to do that and then having the crank migrate forward can ruin your day. There are some pins which can fall out and if you don't notice it, when everything is retightened, you'll bend things and then the only recourse is a full bottom end tear down...you might be able to fix things through one of the engine case openings. Several discussions on blocking the crank. Snowbum has an extensive website which discusses this...and much more. Check my sig line for links.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  4. #4
    Superkraut typ181r90's Avatar
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    Gear oil reeks of sulfur, you'll be able to tell if it's engine oil or transmission oil. I'd just replace everything while you're in there, I did when I had my flywheel off for lightening.
    // 1975 BMW R90/6 (cafe'd) // 1957 BMW R60 (in pieces) // 1967 Aermacchi/H-D Sprint 250 SS (custom special) // 1973 VW Type 181 Custom SOLD )

    http://symphonyofshrapnel.blogspot.com

  5. #5
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    I'm all in...

    I think the best answer is to go for broke and do it all. Having sat for too long, I'm pretty sure there are more leaks on the way.

    I've read some very thorough and detailed instructions on how to replace the main seal, oil pump seal(s) and the danger of allowing the crankshaft to move forward.

    What I haven't found is how to replace the transmission input shaft seal.

    Perhaps Clymers covers that.

    At any rate, thanks guys. I'll be ordering parts and special tools tomorrow.
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  6. #6
    Administrator 20774's Avatar
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    The input seal to the transmission is relatively easy. The hard part is finding the right way to pull the old one. Snowbum discusses on his website some ideas. One is to drive some sheet metal screws into the outside and then use a slide hammer to pull it out a bit at a time. I tried that on my /7 and it wasn't budging. I took the transmission up to the BMW dealer and he did it in 20 seconds and didn't charge me anything. Me likey!! He used a seal puller...looks like this:

    http://www.amazon.com/Lisle-56750-Se.../dp/B0002SRCKG

    He used the holes I had punched into the seal to lever it off. Brook Reams did a great documentation of a /5 rebuild...this was one of the topics of his blog.

    http://brook.reams.me/bmw-motorcyle-...build-project/

    A number of various rebuild discussions/pictorials are given here:

    http://forums.bmwmoa.org/showthread....es-with-Photos
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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