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Mohan Family | profile | all galleries >> Pushrod Tube Seal Replacement on Airhead BMW engine tree view | thumbnails | slideshow

Pushrod Tube Seal Replacement on Airhead BMW engine

These are the photos from the seminar Lance and I did at the 2008 Pennsylvania Airhead Supertech Weekend, February 1-3, in Boyertown, PA. Click on the first thumbnail below to view the large picture and see the detailed caption. Beneath the caption, you can re-size the picture for a larger or small view. On each page, click "next" to advance. You can return to the thumbnails at any time.

• References:
o Scot Marburger, http://www.airheads.org/content/view/304/98/ or http://www.gunsmoke.com/motorcycling/r100gs/pushrod_tubes/index.html
o BMWMOA Tech Forum, http://www.bmwmoa.org/forum/archive/index.php/t-2080.html
o Snowbum, http://bmwmotorcycletech.info/pushrodseals.htm
o Clymer, BMW R-Series, 1970-1994, Ch. 4.
o Oak Okleshen, Boxer Top End Disassembly & Reassembly, 1970-1995
o Anton Largiader, “Airhead Rocker Arms and Posts”, http://largiader.com/tech/rockers/

• Tools needed:
Finned exhaust nut wrench
Assorted spanners & sockets
Circlip pliers or small L-hook, depending on model year
H-shaped jig for adjusting ’70-’75 rocker arm assemblies
Rubber mallet

• Parts needed:
Pushrod tube seals (2)
Wristpin circlip(s)
Cylinder base O-rings ’78-on
Cylinder stud O-rings ’76-on
Optional: spare finned exhaust nut
Optional: spare valve-cover gasket

Re optional parts: if you live 10 minutes from a dealer, you can pop over in the car if you screw up your exhaust nut or lose the circlip. If you live 100 miles from the dealer or get all your parts by mail, you might want to stock these spares so you don’t sideline your bike for a week when a 2 hour job runs into a roadblock.

• Materials:
Anti-seize (finned exhaust nut threads, spark plug threads)
Cylinder base sealant
PRT seal lubricant
Clean engine oil or assembly oil

• Lubing PRT seals:
o Silicone grease on inside, engine oil on outside – Scot Marburger, http://www.airheads.org/content/view/304/98/
o Silicone grease on inside, engine oil on outside – Snowbum, http://bmwmotorcycletech.info/pushrodseals.htm
o GE Clear Silicone Auto Sealant, inside and out – Tom Cutter, email 12/18/07
o Gascacinch (VW dealers), inside and out – Matt Parkhouse, email 12/23/07
o Engine oil, inside and out, NO sealant – Oak’s Top End Manual

• Sealing cylinder base:
See http://www.gunsmoke.com/motorcycling/r100gs/sealant/index.html
Cutter: Three Bond No. 1209, aka Yamabond
Clymer: Three Bond No. 1216
Oak: Hylomar or Permatex Hi-Temp RTV No. 27B
Parkhouse: VW Gascacinch
Snowbum: Dri-bond (BMW dealers may have it); Permatex Hi Temperature RTV, type 27B (81422); and Pro-Seal red silicon RTV (80726), Hylomar
O-ring (’78-and-later):Lube with engine oil no more than 15 minutes prior to reinstallation.

Acknowledgments: THANKS to the following:

Maryland Airmarshal Lance McKay, for the use of his R50/5 for most of these photos, his hospitality and the use of his tools and garage, and finally for agreeing to help me with this hare-brained project.

Pennsylvania Airmarshal Todd Byrum, for the use of his workshop, and his support and advice in developing this presentation. PA Airheads ROCK, thanks to Todd.

Pennsylvania Tech-marshal Bob Sipp, for keeping us on our toes and answering a zillion stupid questions.

Al Vangura, for the use of his exquisite cutaway '82 R80/7 demonstration motor, featured in several of these photos. Al is an incomparable machinist, and his beautiful cutaway components have lead many Airheads down the path of mechanical enlightenment.

Oak Okleshen, Tom Cutter, and Matt Parkhouse, for their assistance and advice supplied in the preparation of this presentation.

Disclaimer: Any errors or omissions in the following directions are my own, and not attributable to any of the above contributors. That said, if you attempt this procedure, you’re assuming responsibility for the welfare of your engine and the safe operation of your motorcycle. If you aren’t confident about proceeding, consult a more experienced mechanic or your BMW dealer.

Your comments and questions are invited. You can add them below, following the thumbnail pics, or email me at 4mohans@safe-mail.net. If you expect a response, email me.
Basic steps
Basic steps
Required tools
Required tools
Pushrod tube seals
Pushrod tube seals
Pushrod tube seals.
Pushrod tube seals.
Degrease and wash engine.
Degrease and wash engine.
Degrease and wash engine
Degrease and wash engine
Your basic SWB 1970 R50/5
Your basic SWB 1970 R50/5
The finned exhaust nut wrench.
The finned exhaust nut wrench.
Remove exhaust.
Remove exhaust.
Exhaust nut removed.
Exhaust nut removed.
Correct assembly of exhaust hardware.
Correct assembly of exhaust hardware.
Remove exhaust.
Remove exhaust.
Unbolt the headers from the mufflers.
Unbolt the headers from the mufflers.
Remove exhaust.
Remove exhaust.
Remove carb.
Remove carb.
Remove carb.
Remove carb.
Carb removed.
Carb removed.
Remove the valve cover.
Remove the valve cover.
Removing rocker arm assemblies and pushrods.
Removing rocker arm assemblies and pushrods.
Remove rocker arm assemblies and pushrods.
Remove rocker arm assemblies and pushrods.
Remove rocker arm assemblies and pushrods.
Remove rocker arm assemblies and pushrods.
Remove rocker arm assemblies and pushrods
Remove rocker arm assemblies and pushrods
Rocker arm assembly with needle bearings.
Rocker arm assembly with needle bearings.
Remove rocker arm assemblies and pushrods.
Remove rocker arm assemblies and pushrods.
Another way to do it is with screws on a board, and labeled.
Another way to do it is with screws on a board, and labeled.
Pull jug out partway.
Pull jug out partway.
Pull jug out partway.
Pull jug out partway.
Pull jug out partway.
Pull jug out partway.
Pull jug out partway.
Pull jug out partway.
Pull jug out partway.
Pull jug out partway.
Pull jug out partway.
Pull jug out partway.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Remove wristpin.
Inspect wristpin.
Inspect wristpin.
Remove jug with piston in cylinder.
Remove jug with piston in cylinder.
Remove jug with piston in cylinder.
Remove jug with piston in cylinder.
Finish removing the jug.
Finish removing the jug.
Remove jug with piston in cylinder.
Remove jug with piston in cylinder.
Replace pushrod tube seals.
Replace pushrod tube seals.
Replace pushrod tube seals.
Replace pushrod tube seals.
Detail view of piston crown.
Detail view of piston crown.
Replace pushrod tube seals.
Replace pushrod tube seals.
Correct piston orientation.
Correct piston orientation.
Correct piston orientation.
Correct piston orientation.
Replace pushrod tube seals.
Replace pushrod tube seals.
Prep cylinder base area for reassembly.
Prep cylinder base area for reassembly.
Cleaning cylinder base.
Cleaning cylinder base.
Cleaning cylinder base.
Cleaning cylinder base.
Cylinder base gasket
Cylinder base gasket
Cylinder base on jug suitably cleaned.
Cylinder base on jug suitably cleaned.
Another view of the cleaned cylinder base.
Another view of the cleaned cylinder base.
Small o-rings seal top cylinder studs.
Small o-rings seal top cylinder studs.
Close-up of large and small o-rings.
Close-up of large and small o-rings.
Prepare cylinder base area for reassembly
Prepare cylinder base area for reassembly
Cleaning the cylinder base area
Cleaning the cylinder base area
Cleaning the cylinder base area
Cleaning the cylinder base area
There, much better!
There, much better!
Small o-ring on '76-and-later motors.
Small o-ring on '76-and-later motors.
Clean cylinder base area.
Clean cylinder base area.
Clean cylinder base area.
Clean cylinder base area.
Prepare cylinder base area for reassembly
Prepare cylinder base area for reassembly
Hylomar
Hylomar
Permatex High-Temp RTV Silicone
Permatex High-Temp RTV Silicone
Just a dab'll do ya
Just a dab'll do ya
Oil gallery outlet at the top cylinder stud.
Oil gallery outlet at the top cylinder stud.
Correct thickness of sealant application.
Correct thickness of sealant application.
Applying sealant to cylinder base of jug.
Applying sealant to cylinder base of jug.
Prepare cylinder base area for reassembly
Prepare cylinder base area for reassembly
New wire clip for wristpin.
New wire clip for wristpin.
Installing the wire clip.
Installing the wire clip.
Seat cylinder base and PRT seals
Seat cylinder base and PRT seals
Seat cylinder base and PRT seals
Seat cylinder base and PRT seals
Seat cylinder base and PRT seals
Seat cylinder base and PRT seals
Seating the seals by installing the bottom cylinder stud nuts first.
Seating the seals by installing the bottom cylinder stud nuts first.
Reinstall pushrods & rocker arm assemblies.
Reinstall pushrods & rocker arm assemblies.
Reinstall pushrods & rocker arm assemblies.
Reinstall pushrods & rocker arm assemblies.
Adjust alignment of rocker arm assemblies
Adjust alignment of rocker arm assemblies
Aligning the rocker arm assemblies
Aligning the rocker arm assemblies
Correct alignment of the pushrod in the PRT
Correct alignment of the pushrod in the PRT
Torquing the cylinder studs.
Torquing the cylinder studs.
Setting the valve lash.
Setting the valve lash.
Setting the valve lash.
Setting the valve lash.
Setting the valve lash.
Setting the valve lash.
Refitting the valve cover.
Refitting the valve cover.
Reinstall exhaust and carb.
Reinstall exhaust and carb.
Reinstall exhaust and carb.
Reinstall exhaust and carb.
Oak's top end manual -- invaluable!
Oak's top end manual -- invaluable!