Oil pan screws - rubber washers? Sealant?

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

  1. nevada72

    nevada72 Milwaukeeish

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    Crap. They're spring washers?? Those a-holes have been laughing at me behind my back all this time!

    Seeing as I'm admitting stupidity - I also found the lowest nut and washer (the one opposite the one by the spark plug) missing when I went to remove the heads the other day. :baldy It's a miracle I haven't blown the damn thing up by now.
    #41
  2. melville

    melville Long timer

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    It's a German thing. ACVW does it also.
    #42
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  3. nevada72

    nevada72 Milwaukeeish

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    I measured it tonight. The surface that the rubber seal meets is 91mm from where the tube comes out. The collar itself is 5mm, so the other dimensions would be 86mm to the back of the collar (the surface facing where it comes out of the cylinder). Which means the middle of the collar is 88.5mm from the base. Does that seem right?

    Also, the collars are 100% not moving. I scratched the crevice and didn't see obvious brazing, but they are really really on there. And the tubes themselves are all flush with the opening at the top facing the valve covers - very tight.
    #43
  4. bmwrench

    bmwrench Long timer Supporter

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    That should work. I'd do a trial assembly, with no piston, to see how the seals fit.
    #44
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  5. nevada72

    nevada72 Milwaukeeish

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    Wow - Thanks!
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  6. Beemerguru

    Beemerguru Beemerguru...G/S guy

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    That's what you use to push the tubes in and out of the cylinder.

    The one you need looks like the front part of the tube is sliced off at an angle so it fits up against the stop so you can hit the tube that moves the stop up against the seal and pushes it in closer to the block
    #46
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  7. nevada72

    nevada72 Milwaukeeish

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    I think I got it. Prior to this thread I really didn't give a lot of thought to the pushrod seals. The conversation with you guys really enlightened me as to how they work I think. The concept is very simple - they are held in by pressure from the collar. Obvious sure. But again, I just didn't think about it. Maybe because at this stage of assembly I was more a "helper" than worker. When we installed them in the winter I was told the idea is to twist them in as you apply pressure. I (the amateur) think that its unnecessary. I also factored the input here that sealant is unnecessary. I don't like sealants to stop leaks. I see them as temporary, so this resonated with me.

    To start I cleaned everything up very well. That was the most time consuming part of this whole deal. Once everything was spotless I added spacers on top of the collars. I found some bushings that fit over the tubes perfectly. I used JB Weld to seal them against the collars to make sure they wouldn't leak between the spacer and the collar. I did this because I had noticed that the seal that was leaking didn't seem to bein all the way. I could see the beginning of that first rib. Again, based on discussion here, I reasoned that the collar wasn't at the exact right spot to apply sufficient pressure to push that seal all the way in. The tubes are in great shape and the collars are on there monkey tight, so they must have been brazed somewhere along the way. Based on that I wanted to work with what I have vs the stainless replacements. Which would also create a lot of downtime for me.

    I started reassembling everything. I made sure to very lightly lube the seals with clear synthetic food grade grease. I also did a very light film on the "sockets" that they fit into on the block. Once everything was together it was obvious that the seals were all the way in.

    Here's what I did. You can see the spacers that I added. Not much, but enough to do the trick I think.

    pushrod seal.jpg

    Hopefully I didn't overlook some reason that this spacer treatment wouldn't work. And of course running the bike will reveal whether or not it worked. But I just can't see why it wouldn't. The seals are definitely all the way in and very tight, but not compressed too much so as to distort the rubber.
    #47
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  8. Plaka

    Plaka Brevis illi vita est

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    i lube with alcohol instead of grease for the same reason I do it with grips. It evaporates in time leaving nothing but a tight fit. It makes rubber slippery without taking up any space it self. your grease may dissolve in engine oil leaving a pathway to leak. the rubber won't be absolutely against the metal.

    looks like a very clean job. too bad it isn't anywhere that shows. :D
    #48
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  9. nevada72

    nevada72 Milwaukeeish

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    I gave that some serious thought before doing it and had the same concern. The silicon grease I use is super clean and I used it very sparingly. I rubbed it on and wiped it off. That left it slick but with no extra residue. That said, I missed that you leave the alcohol wet on first read. That makes total sense and is likely the better way to go. Hopefully my method works. If not, well........at least I'm getting proficient at remove and replace.
    #49