Leaking Head

[reimerdavid]

Hello this is his son again with my 1983 R100RS. I haven't been able to ride that much this year. One reason it I have a oil leak from the valve cover. Last year I dumped the bike in the parking lot. Picked it up and rode home all that happened was it scraped the valve cover. So in the winter I went on ebay and bought a used valve cover for my bike. Than ordered a new gasket from bobs BMW. So I installed them by lubing the gasket up with a thin strip of oil than tightening the new cover down. I thought to myself easily done. So spring rolled around and I took her out, rebuilt carbs new paint job oo boy did we have some fun. So I got home and parked the bike after checking my shoes and the bike no oil. Great I thought until the next day I went out to take another ride and she was leaking:cry from the valve cover! So I took it off and checked it out nothing seemed to be a miss. So I put it back together went out for another ride after adding a tad of oil to her. Came back same thing. So I tried some gasket sealant didn't help. So did I do something wrong any advice would be great.

[jforgo]

Don't ever use sealant - it easiliy gets in small oil passages.
In any event, I am assuming here something is warped. What follows here worked for my pulse air victimized warped heads heads. Clean ALL that stuff off, and get the neoprene valve cover gaskets from Rocky Point Cycle.

[Isamemon]

the nopreme seals well, sometimes however, when you take them off to adjust valves you might find they expanded
also, the ones i got are orange, looks strange

[barryg]

One thing to check is flatness of the 2 surfaces. Use the edge of a good combination square and lay it across the face of the head and valve cover and do it in several different directions. What your looking for is high and low points, there could be a gap in the center of either or a high point in the center and the scale will rock like a teter/toter. I use to do heads for a living in another life. I've seen heads where owners have tried to get a stuck valve cover gasket off and used files and belt sanders. I've also seen a lot of prying marks on both. None of this is good for heads and valve covers. Could be your problem, so it's something to check.

[skiteach]

While the cover is off, you may want to clean the gasket area, of the head and look for a crack. Seems unlikely and I really hope that it's a warp! If there is a crack, JB weld would pobably work. As long as surface is very clean and not oily it should stick. I've done some cylinder heads this way, I've also Tig welded a few ( all automotive)

[Bigrider]

A couple of things to check. As BarryG mentioned, flatness of the valve cover is important. I recently had a leak and took the valve cover off, took the studs out by doubling up the two nuts so I could "unscrew" the studs. Once off, I took a sheet of 300 grit wet/dry paper, the black kind, and place it on a plate of glass (flat surface). Using a circular movement, I rubbed the cover around a few times. One can then see from the pattern on the cover if there are extremes in high/low spots. Keep sanding until the cover is all the same kind of shinny. Another area to check is the center stud. I found mine was about ready to pull out and could not take the torque required to keep the cover on tight without the fear of pulling it out. Be careful, you really don't want to pull that stud out. Until I fix the center stud, I used a light coat of high temp sealant. I don't think you have to worry about small bits falling off if you keep the thickness down. For now the head is leak free. Now, If I could only get the pushrod seals from seeping...Hey it's an 1984, things wearout and or dry up.

Dave H
San Antonio, TX

[lkchris]

BMW Airhead valve cover gaskets come with adhesive already included. It's on the side with the lettering and this side contacts the head.

When heat activated, the adhesive nicely adheres the gasket to the head and then you can do regular maintenance without replacing the gasket for maybe 10 years. Don't glue it to the valve cover, obviously.

It's a good idea for folks used to working on American automotive equipment to forget all that when working on German stuff, because it's apples and oranges. Yes, I've used plenty of 3M weatherstrip adhesive to glue pathetic cork gaskets to smallblock chebbie valve covers, but that's not the way it works with German stuff, save perhaps for old VW Beetles, which of course are a 1930s design.

It's maybe more and more likely these days for new owners to encounter cylinder heads damaged by folks trying to pry the valve cover off prior to discovering the small nuts/studs at the outer edges (more erroneous transfer of American technique). Surfaces also get damaged by people trying to scrape off their previous applications of various goop from tubes. If your surfaces aren't so good, there are aftermarket silicone gaskets that can be used as a crutch in this instance. They're a PITA to work with, but they are pretty good at sealing when the surfaces are damaged.