Leaking push rod tube seals

[FatAl]

My recently acquired 1990 R100GS has oil weeping from around the push rod tube seals. It has been suggested to me to try tapping the seals in, by using a cut off metal tube that will just fit over the push rod tube, and hence press the seal further into the casing.
Has anyone tried this method? I'd rather do this than remove the cylinders.

 

[cookie]

that only works on the early models with push fit retaining rings on the tubes. later ones are welded in place.

you need to change the pushrod seals.

 

[Garry H]

that only works on the early models with push fit retaining rings on the tubes. later ones are welded in place.

you need to change the pushrod seals.

Are you sure ?
It worked perfectly well on my 92 GSPD and cured the leak

 

[cookie]

Are you sure ?
It worked perfectly well on my 92 GSPD and cured the leak

http://www.bmwmoa.org/forum/showthread.php?t=24332

 

[electric_monk]

Two hours ago Jaythro just recommended i do the same thing to mine to stop the weep. As far as I am concerned his advice is to be heeded. Gonna try it next week when i'm able to bend down again.

 

[FatAl]

thanks for the replies, I think I'll give it a go. Nothing ventured, nothing gained...

 

[DrFarkoff]

thanks for the replies, I think I'll give it a go. Nothing ventured, nothing gained...

Take the bike for a wee run first cos it's easier when it's warmed up

scribe a wee line where the tube meets the head cos you are only looking to tighten the push rod seal not stick it into the crankcase so you only want 1 mm or 2 mm of a gap between your scribe line and the head and see how you get on with that ?

When it's warm set your modified tube against to lower lip and give it a thump with the hammer start gentle and work up to solid thumps, rather than clout hard and make a mess at the start, Kee p an eye on your scribe gap and watch the bloody exhausts!!!

2 things when the seals are warm they are less likely to crack or split!

and the steel (or stainless steel Flash Gits!) will move much easier if the alloy is warmer than them!

Cookie The tubes slide in the head section to allow you to tighten up the seals I've never seen any where the ring was loose?

 

[cookie]

Cookie The tubes slide in the head section to allow you to tighten up the seals I've never seen any where the ring was loose?

i found two possible dates for the changeover earlier, but didn't bookmark, so now lost in the ether. think it was mid 70s or early 80s when bmw started brazing the collars on.

whatever. the seals leak because they have gone hard, but your method might prolong their life a bit. guess it doesn't take much effort to try it, but it never worked for me.
mind you, i never hit them hard enough to shift the tubes. it was my intention to move the collars, then i found out they were fixed

changing the seals works though

 

[Garry H]

You don't need to hit them very hard at all...
I used a bit of wood thats how little force it took to move them...
You can see how much they have moved if you look carefuly where they press into the barrels...1 to 2 mm is pleanty..
If that does not cure the leak then fit new seals

Warm the engine up so the rubbers are a bit softer..
You move the tubes in the barrels not the rings on the tubes..
Did it on mine 3 years ago now if done carefuly it works fine..Mine is still leak free and it's only a 2 minute job

 

[BegesRus]

Mate did mine and cured the leaks - worth a try before breaking into the heads

 

[cookie]

looks like they've had the same discussion on ADVrider.

 

[John Roberts]

All this talk of thumping pushrod tubes makes me squirm, so I'd like to know if anybody has loosened the tubes at the top end where they fit into the cylinder as a result of thumping and ended up with another leak from there?

As it happens I'm particularly interested because I had this problem with the 2.8 litre A65 Continental flat four engine (a four cylinder boxer arrangement) fitted in a plane I used to have, a Taylorcraft BC12-D. A lovely little thing it was, it looked very similar to a Piper Cub and was designed by the same man. Anyway, I made a special tool to expand the pushrod tube in the cylinder, it didn't work on a leaking tube but it would seat a new tube in so that it wouldn't leak.

I used it on my own engine and it has been used successfully by a Licenced Aircraft Engineer on lots of other engines. So, if anyone does have this problem perhaps I might be able to help.