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Thread: Pushrod tube removal

  1. #1
    atyourservice
    Guest

    Pushrod tube removal

    Just got my barrels back from the machine shop. I have new stainless tubes to be installed. What is the proper procedure for the removal? Heat? Thanks.

  2. #2
    Manfred
    Guest
    I have a slight weepage from my pushrods, researched this a bit a while back. Here's what I saved:

    Push Rod Seals from http://forums.bmwmoa.org/showthread....ht=spark+plugs



    well, you don't have to pull the cylinder off the piston to change the pushrod seals.

    you can pull the cylinder out quite far when on tdc (right where you would have started a valve adjustment) and leave the whole thing assembled; enough to pop off the old pushrod seals and get new ones on.


    DO grease the inside of the pushrod rubber with a hi temp break caliper silicon grease to allow a stick-free (leak-free!) heat expansion and oil the outside of the rubber. make sure the lines on the pushrod seals point down. be careful to get the old rubber off the block and tube without dropping stuff into the block. this is also a good time to inspect the lifters for wear with a magnet on a stick.


    it is my practice on high mile machines to only replace seals when there are allot of leaks and its worth doing a bunch of stuff at once and being thorough. it is advisable to also change the cylinder base gasket too whenever it's integrity is compromised; never loosen all 6 head bolts at once unless you mean it. i always apply a micro thin film of warm, non-harding hi temp rtv (orange?) to both sides of the base gasket. you may have rubber orings also, i don't know you model so may or may not want sealant. i deal mostly with /5's and being very careful not to get any goop in or too near the oil passages on the top 2 bolts.

    so now that you've loosened all 6 head bolts for those pesky leaky pushrod seals (you've put a si grease on the new ones right, wouldn't want them leaking in a week), better change that head gasket too.if the machine wasn't burning oil (inspect and clean the spark plugs at some point a few rides before you start this process and that will give you a decent idea of whats happening in the combustion chamber), then i wouldn't worry about pulling the piston clear of the cylinder unless it looks like this one with an inch of coke and frozen rings.

    when pulling the cylinder free of the piston or rod, have a hand ready to catch the rod so that it won't nick the case and hold it up with a rag.


    One can simply cut the new o-ring, wrap it around the crank (or stud, depending on the o-ring) and Super-Glue(tm) the ends back together. There ARE easy ways to do things that are not wrong. In other words, the method using less disassembly requires less work, fewer parts (does not require a new head gasket), renews all the rubber bits that touch the crankcase (p.r. seals and o-rings) and when done right, nothing leaks. Just sayin'.

    BTW, the o-rings involved live in a nearly-hermetically sealed environment. Pushrod seals are exposed to the elements. Therefore, their lives are very different.

  3. #3
    atyourservice
    Guest
    I've got the seals off. That was not the issue. Im talking about the tubes themselves. They seem to be pressed in. I wasnt sure if a map gas torch and a like-sized punch wouldnt push them out?

  4. #4
    Rally Rat
    Join Date
    Sep 2005
    Location
    Stone Mountain, GA
    Posts
    108

    Pushrog Tube R&R

    You are right about needing heat. They are a shrink fit into the cylinders. Got to Snowbums site. He has pretty good instructions on how to do this.

  5. #5
    atyourservice
    Guest
    Tried snowbums site. Couldnt find the aritcle, found a bunch of other good tid bits. BUT... I heated the barrels and tapped 3 out of four out without incidence. The 4th gave me a bit of trouble, but still came out. I just had to tap it a bit harder than the others. I ordered all the top end gaskets, seals and stainless tubes from the Beemer shop here in CA. They volunteered great advice about the re-installation of the tubes. Keep them in the freezer a whole day before installing. Sounds good. I may even heat the barrels a bit too, just for an extra snug fit. Reading snowbum's site made me question my own mechanical intuition. He's got gobs of sage advice, but introduces so many variables on how you can screw up your airhead. I suppose I should kiss my wife and kids goodbye for the weekend and read through more if his site. Thanks for all the help.
    Jason

  6. #6
    Liaison 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
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    18,216
    Did you measure where the old tubes were before you tapped them out? That would give you a point of reference when you install the new ones. You want them at the right depth to put the correct amount of squeeze on the pushrod tube seals.
    Kurt -- Forum Liaison ---> 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!

  7. #7
    atyourservice
    Guest
    Yes, I visually made note that all four tubes were just about flush with edge of the bore. BTW, I found Snowbum's article on tube replacement. He doesnt seem too in favor of it. I'll tread lightly and follow his words of advice when I get to that point. I doesnt seem too technical, you just have to be patient with the set up and work quickly but deliberately. I'll post the pics of the outcome on my other thread. Thanks. Loving this forum so far.
    Jason

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