78' R100/7 Push Rod Tube Seals

Finally starting the PR Tube seal replacement on my /7?its my first time so be gentile.

I have been doing a lot of reading in preparation for this project and I think I'm ready.
I already have the carbs off and rebuilt them. The exhaust nuts were not too tight.

Everything came apart easily without issue.

Found out I do not have base O-Rings so Loctite 510 sealant will be picked up tomorrow.
?I know, use very little and use extreme caution around the top stud/o rings.
I will de-carbon the heads and pistons before reassembly.

Are there secrets, hints and or tips to installing the new PR tube seals? I read to oil the outside part that goes into the block and use silicone grease on the inside where it mates to the push rod tube itself.










I will take a few more photos as I proceed.

I did a topend on my R100/7 that finished about a year ago. I covered it in this thread:

http://forums.bmwmoa.org/showthread.php?64756-1978-R100-7-Topend-Overhaul

So, you're just doing the seals? How many miles on the topend? I had 100K and ended up converting the head to unleaded parts.

I used Oak's topend manual as my guide...I found it quite helpful. Sounds like you have the basic idea on lubricating the seals. Drawing the head/cylinder back to the block requires some care. IIRC I only used the bottom two rocker nuts to draw it close...if the top nuts are used, it tends to draw it down unevenly and the pushrod tube seals will not insert evenly. Be sure the small o-rings are in good shape and not pinched when reinstalling...sounds like you're not replacing those.

Again, Oak's manual was very helpful.

Along with the PR Tube seals, I am replacing the top stud o rings and head gaskets.
The rocker cover gaskets are new.

THANK YOU for the tip on using the lower rocker stud bolts to draw things up?.I did not know that.

Nice thread on your top end job.

I hope I use enough but not too much sealant, that will be the trick.

Be sure and check out Snowbum's site for info on changing the pushrod seals.

I helped to a set recently and found this video helpful. http://www.youtube.com/watch?v=A47LiKSYD9o

Wayne

Whenever we are applying a gasket sealant, we find a Q-tip works pretty well as an applicator.

Finished it up on 1/1/14. Everything went well except someone broke 3 of the 4 retaining washers loose on the PR Tubes. Probably tried to hammer them in to add pressure to the rubber seals. How'd that work for him?
I cleaned the tubes with scotchbrite and acetone then secured the rings with JB Weld. I worked it under the ring by sliding it back and forth over the wet JB, then set them to the proper position, cleaned the surface that mates with the seal and Viola!

The heads and pistons got de-carboned and all surfaces were cleaned with acetone before assembly. I used Yamabond 4 because no one in our little town had Loctite sealant.

Gonna drop the pan and clean everything in there, then its total reassembly.

Thanks to everyone that helped along the way?and HAPPY NEW YEAR!

Glad things worked out! I'm not sure I understand the need to try and reposition the collars on the pushrod tubes. If they were fine when they came off, there was no real need to reposition them. I can never remember which, but some of the years, the collars are brazed on and beating on them defeats their purpose. If they are moved too much, they can split the o-rings and create worse problems.

I posted a picture of the correct position of the collars relative to the cylinder base. That picture is here:

http://forums.bmwmoa.org/showthread.php?53365-Help-with-the-top-end!&p=682593&viewfull=1#post682593

The illustration in your post is EXACTLY how I did them.

I had to reposition and secure them because they were loose and slid back and forth about 1/8"