Use of gasket sealer/adhesive + paper gaskets

[hatcreek]

Hi folks. I'm in the process of a complete teardown/rebuild of a '78 R100/7, my first airhead. I took the transmission apart this week and will be replacing shaft bearings, seals and shifter mechanism springs. A general question this brings up related to all sorts of machined surface sealing on the airhead including engine valve covers, oil pan, transmission cover, final drive cover, etc.. Should I use the replacement paper gaskets with no other adhesive or bonding agent, or do people with experience recommend using a thin coat of grease or loctite 573 in addition to the gaskets? Haven't seen a clear answer to this anywhere so appreciate any feedback.

 

[robsryder]

The answer that I've heard over the years from various airhead gurus has been to NOT use a gasket sealer with BMW gaskets. Surfaces should be carefully cleaned (e.g., free of old paper gaskets - I have found this to be challenging with old final drives, but once cleaned, don't leak with new gaskets).

For oil pans and valve covers I have been using silicone gaskets for more than 20 years. These silicone gaskets are re-usable, but must be clean prior to installation. Very low torque values are specified for these silicone gaskets (around 3 to 4 ft-lbs).

For my airheads the silicone gaskets came from the now defunct business Rocky Point Cycle when they were in Ohio. Another source, which I have not made a purchase from, is -

BMW Archives

realgaskets.com

I have made many purchases from EuroMotoElectrics (EME) and find this to be a good business. BMW gaskets for airheads are available at a lower cost than from the dealer -

https://www.euromotoelectrics.com/category-s/3282.htm

If you are new to airheads if might be worthwhile to peruse the videos from Boxer2Valve. I have purchased transmission seals, bearings, etc. from them. I had Boxer2Valve machine the groove and install the missing circlip from the transmission on my 93 R100GS-PD.

https://www.boxer2valve.com/

Tools for servicing the airhead transmission and other stuff for airheads was obtained from Cycle Works -

CycleWorks.net LLC, The original source for tools and parts for your antique, vintage, and classic BMW motorcycle or Isetta car

CycleWorks.net LLC : - Isetta & BMW 600/700 Vintage - R12 to R69S Airheads - 1970 to 1995 Oilheads - 1994 to 2005 Isetta, antique, classic, BMW, motorcycle, tools, service, parts

cycleworks.net

Snowbum's website has a lot of info as does the IBMWR website -

Airhead Tech Articles - The Internet BMW Riders

BMW Type 247 motorcycle maintenance, mostly for 1970-1995 bikes, but some older models also. R50, R60, R75, R90/6, R90S, R65LS, R100, R100S, R100RS, R100RT

ibmwr.org

Snowbum,Snobum,BMW motorcycle repair & information, Airheads, Oilheads, Classic K,

Snowbum, snobum, BMW motorcycle repairs, sidecars, Airheads, Oilheads, Classic K,

bmwmotorcycletech.info

 

[hatcreek]

Thanks for the response. I'll plan on using dry gaskets then and will take a look at the silicone valve cover and pan gaskets although I already have paper in a kit I purchased from Siebenrock. Makes sense that silicone would create a superior seal though and after having all this aluminum vapor blasted the last thing I want is leaks. And yes, very familiar with euromoto and cycleworks - I've been a frequent shopper at both the past couple months. Also been using the snowbum info a lot - I'll check out the IBMWR site - that one's new to me. Thanks!

 

[20774]

On the pan gasket, one thing to look at are the bolts. Torque to spec or use a nut-driver approach to ensure they're not over tightened. But additionally, note that some of those bolts go through the case and the threads end up inside the sump exposed to oil. Oil can migrate down the threads. Use a non-hardening sealant like Permatex Ultra Gray on the threads to seal them.

 

[lkchris]

Just a note ... when a genuine BMW paper gasket has printing on it, that's the side with the heat activated adhesive. So put that side against the cylinder head for valve cover gaskets. Another note ... these gaskets are reusable--when left in place--for a long, long, time.

I think the best and nearly only solution for the oil pan is the previously mentioned silicone gasket. Although BMW doesn't specify it, the silicone gasket guy recommended loctite on the screws.

I once purchased---better term rescued--- an RT that was owned by a guy with little mechanical sympathy. The tool box was in backwards of all things. He was apparently one of seemingly quite a few that imagined the valve covers were held on by that single central nut and there was evidence of pry marks on the cylinder head valve cover faces. This was a good use for the silicone valve cover gaskets as they didn't leak despite the damaged surfaces.

 

[CaptCF]

On the pan gasket, one thing to look at are the bolts. Torque to spec or use a nut-driver approach to ensure they're not over tightened. But additionally, note that some of those bolts go through the case and the threads end up inside the sump exposed to oil. Oil can migrate down the threads. Use a non-hardening sealant like Permatex Ultra Gray on the threads to seal them.

I recently had to remove and reseal a leaking oil pan on an S1000XR and I used Permatex Ultra Gray both around the mating surface of the pan (XR has no paper or silicone gasket available for the oil pan) and on the threads of the oil pan bolts as you describe. Spec was to use new bolts with a very specific torque and tightening order. No leaks since.

 

[ebeeby]

Local shop marred the end of my driveshaft housing disassembling the shaft so I could send swingarm to San Diego for stiffening kit.
I have had to use Permatex Black on the swingarm end with the paper gasket ever since.