Oil pan screws - rubber washers? Sealant?

Discussion in 'Airheads' started by nevada72, Sep 27, 2021.

  1. nevada72

    nevada72 Milwaukeeish

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    Greetings all. Chasing down some minor oil leaks as mentioned in other threads. In this case I'm replacing the oil pan gasket. I have the pan itself, as well as the block mating surface clean as a whistle. I have the appropriate gasket which I am to understand does NOT use any kind of sealant. Makes sense.

    BUT - what about the screws? The holes aren't blind - they go right up into the oil reservoir. I would think oil would work it's way down the threads. I did see telltale oil drips on the hex head screws when I took it apart. Should I be using a sealant? Or a steel/rubber washer? I haven't seen mention of this anywhere but when I was having a tech day, the local Air Marshal said to use sealant on two particular screws. But it's more than two that aren't blind. I'm thinking I need to, at minimum, use thread sealant on all the screws.

    Also, I ordered a stainless hardware kit from Hucky. Nice for most applications elsewhere on the bike but I'm not 100% sure about using the oil pan screws. And especially the split lock washers vs the solid washers that are OEM.

    Any pointers are appreciated.
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  2. MonzaCross

    MonzaCross When life throws you a curve, lean into it

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    What bike? My /2 screws would weep some oil and needed some sealing but I have never had a drop from my 1975 r90/6. I have had some oil drip off my /6 pan bolts but the source of the oil was upstream and not the oil pan bolts.
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  3. nevada72

    nevada72 Milwaukeeish

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    Sorry - 71 R75/5.
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  4. bmwrench

    bmwrench Long timer Supporter

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    Only the /5 bolts are open, although even later bikes have one open, below the oil filter cannister. Hylomar is a good choice for sealing these.
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  5. nevada72

    nevada72 Milwaukeeish

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    Much appreciated. :beer As I suspected.

    I think I'll skip the split washers and use the oem flats. Stainless in aluminum set to inch pounds makes me nervous enough.
    #5
  6. Plaka

    Plaka Brevis illi vita est

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    I like the metric warpy lock washers. Are these what you mean by "flat"? just use a torque wrench. Stainless is soft. Easy to extract if you break one. This is a decent application for simple new steel bolts though. Always greasy down there. It's supposed to be. Sheesh!.

    Check your bolt lengths for a short one. Always install with the oil filter cover off. make sure that bolt does not go through and smash the canister.

    observe tightening sequence.
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  7. Pokie

    Pokie Just plain Pokie.

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    They are not flat washers, they are wave washers, as Plaka states. They are just another form of lock washers that doesn't damage the surfaces. Wave washers are available from hardware stores like ACE and Sentry in both metric and SAE.
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  8. nevada72

    nevada72 Milwaukeeish

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    Thanks again gents! Sourced M6 wave washers, coated the base of the SS screws with Threebond 1183, torqued to 25 foot pounds.....just kidding.......inch pounds, then 65 inch pounds using the prescribed sequence. I'm feeling good about it.

    Tomorrow I'll replace the clutch rod washer/seal and put the bike back together. May do the Slimey Crud Run with it this Sunday, or maybe just the RTWC. Depends if I want toi show off style or show off speed. :D
    #8
  9. bmwrench

    bmwrench Long timer Supporter

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    Retorque the pan at 500 miles.
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  10. nevada72

    nevada72 Milwaukeeish

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    Well alright, alright, alright! (he said in his best Mathew McConaughy voice) - it doesn't leak anymore! Between the new oil drain plug crush washer, the new gasket, the sealant, the wave washers, the new rubber clutch seal thing, and some judicious application of more sealant on the transmission studs, the motor is dry as a bone. Success!

    In hindsight the rubber washer idea was a bad one considering the specific torque specs required to maintain a flat interface between pan and block. Glad I didn't do that.

    In other news, while I was in there, I added a pretty sweet side stand. I have no idea what brand it is. I bought it off a guy on Facebook on a /5 page. It's perfect! I like it way better than the Brown stand which relies on a clamp around the exhaust which I was never fond of. This one simply replaces the spacers between the motor and frame. It also has a loop for the center stand spring.

    Kick stand.jpg
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  11. Pokie

    Pokie Just plain Pokie.

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    Looks good!
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  12. nevada72

    nevada72 Milwaukeeish

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    Well it still leaks. :baldy

    But at least not from the pan gasket or clutch pushrod assembly. It looks like the front right pushrod seal is weeping. It's not a lot but it does leave a few drips and I hate visiting friends and dropping oil on their nice concrete driveway. So I guess I'll replace that seal (again!) and hopefully that takes care of it.
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  13. Plaka

    Plaka Brevis illi vita est

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    My friends have bikes that leak more than mine does. That's why they're friends.
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  14. Pokie

    Pokie Just plain Pokie.

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    A leaking pushrod tube seal is often mistaken for a pan leak.
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  15. nevada72

    nevada72 Milwaukeeish

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    Yeah, I can see that. I got lazy and I didn't replace the old gasket. Mainly because it looked fairly new. But I do think it was leaking a bit. And the current leak is somewhat less. So I'll fix that pushrod leak and see where it's at.
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  16. nevada72

    nevada72 Milwaukeeish

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    Well shit.......I pulled it and reset the seal last night and it's leaking as bad as ever from that front right seal. And it's not just weeping or a drop or two - it's a steady, albeit minimal, flow. I just don't get it. I cleaned the daylights out of the whole assembly and used sealant. There didn't appear to be any damage to anything that might create an issue. It all looks very good.

    I have done this twice. And the first time was with supervision! Is there anything I should be doing or ordering that can help? Right now I'm using the plain old seals I got from Rubber Chicken and Threebond 1183. Would Hylomar (as mentioned above) be an improvement? Are there better seals? Any tips or tricks?

    I guess the good news is I can get the bike apart and back together in fairly short order. I think the whole process took me 2 hours last night.
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  17. Pokie

    Pokie Just plain Pokie.

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    If you are talking about the pushrod tube seal, only use BMW parts. If your pushrod tubes are of the later, brazed type, you may have to drift down the tube in the cylinder as there may not be enough pressure on the seal. If your tubes are of the early, compression ring tubes, either the compression ring needs to be pressed down further or needs to be brazed in place (if loose) or the tube itself needs to be replaced. There were also two sizes of tube seals, putting one of the later seals (large) on an early cylinder (small) the leak will be pretty big as it will not seal against the tube itself.
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  18. nevada72

    nevada72 Milwaukeeish

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    Yes - pushrod tube seal. And you may be correct on the tube not providing enough pressure to seal. It seemed that way to me last night - the seal appeared to not be in all the way. And trying to push it in didn't do anything because it simply pushed back out because there was nothing to hold it tight. I'll take a close look at that.

    I believe it's the later brazed type as the pushrod tubes are firmly in place on the cylinders. The seals I have are very tight to those. - no leaking there.
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  19. Plaka

    Plaka Brevis illi vita est

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    To determine if the collars are brazed look for the braze joint. The tube should always be very tight in the cylinder no matter the collar type. The year of the cylinders will also reveal some things. With brazed collars the seal drift applied to the collar will slide the entire tube downward out of the cylinder. It will stay where you put it. With the earlier sliding collar type only the collar would slide and they would not stay where you put then and had to be smacked again every so often to stay tight. The drift is used with full torque on the cylinder studs.

    use the factory seal drift. There are sketches of home made ones for the ever cheep airheads but the factory tool has some subtleties in the geometry, is very good steel and doesn't cost a lot. From the peek at your stable, you can afford one.

    I put mine together without sealant. I lube it, all over, often with alcohol. I want the PR seal to slide freely and make good contact. Just trying to put goop in there can interfere with this. In addition there is no cleanup if I have to tear it down. Mine do not so much as weep.
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  20. nevada72

    nevada72 Milwaukeeish

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    I appreciate the feedback Plaka.

    I'll get a look when I take it off next time for the brazing. I'm not sure if there is some indication as to what it is based on the pics I have - (pre-restoration obviously)
    IMG_3721.JPG
    IMG_3728.JPG

    IMG_3731.JPG

    Here they are after having them honed and cleaned up -
    IMG_4956.JPG

    And then there were these things that came from Rubber Chicken. The guys helping me said they did not apply to my bike -

    IMG_4972.JPG

    I looked for the pushrod tube drift. I didn't find the factory one but this came up -

    PUSHROD TUBE DRIFT I 1951-95 AIRHEADS - $19.00 : CycleWorks.net LLC, The original source for tools and parts for your antique, vintage, and classic BMW motorcycle or Isetta car

    IMG_4028 (1).jpeg

    There is also one by Vech, but it says up till 1969. My bike is a 71
    #20