Leaking right cylendar head

schrader7032 · Post by **schrader7032** » Thu Jun 11, 2009 7:06 am

This thread should be moved to the forum best suited for the topic and to get more exposure.

What year/model bike are you talking about? [Edit...I see by an earlier post, you're probably talking about your '71 /5].

Exactly where it is leaking from? If it's not clear, thoroughly clean up the engine and go for a ride. Then spread some talcum powder around and see where it sticks.

Are you sure it's engine oil? Could it be gasoline? If it's leaking on your foot, then it's either coming from the carbs or the head gasket area or maybe the valve cover. If it's a /5 or later, then it could be from the cylinder side of the pushrod tubes.

In general, it's not true that they all leak. They only leak if there's something wrong. Find out where it's leaking from and then determine how to fix it. Adding rubber o-rings or gaskets is not the normal fix, unless the existing one is worn out or torn. Mating surfaces need to be flat and the cylinder to block surface usually has small amount of sealant on it. However, things like the valve cover and head gasket are put on with no sealants. If the mating surfaces are warped, the best way to fix it is to have it milled flat.

More information is needed...

Kurt in S.A.

hargis7556 · Post by **hargis7556** » Thu Jun 11, 2009 2:05 pm

Kurt;

thanks for your help. Sorry about the misplelling of "cylinders" ijust noticed that.

I will clean it up and ride it. I am sure it is not from the carburator. it is comming from underneath the cylinder abut 4" (in towards the bike) from the covers.

It is a 1971 R75/5

hargis7556 · Post by **hargis7556** » Sat Jun 13, 2009 9:25 am

OK--cleaned the cylindar us this morning--warmed the engine dusted the area and the leak seems to be comming from the aft inboard return tube under the cylinder. It is definitely not the head gasket but one of the tubes under the cylinder.

How do i stop this leak?

Cheer

schrader7032 · Post by **schrader7032** » Sat Jun 13, 2009 10:12 am

If I'm not mistaken, the early /5 models have the pushrod tubes pressed into sleeves which are also pressed into the heads. Later models had the tunnels precast into the heads. These early models are supposed to have an o-ring underneath the rocker arm support blocks to keep oil from leaking past. It looks like #9 in this picture, but it's not on the table...that indicates that it's not needed, but I've heard people mention this on the Airheads list.

http://www.realoem.com/bmw/showparts.do ... g=11&fg=20

Anton mentions this o-ring on this page, under the /5 with bushings.

http://www.largiader.com/tech/rockers/

Has there been recent work on the heads? Maybe that's when this started. If it's the o-ring, then it can be changed by removing the rocker arms, one at a time so you don't fully release the head bolt torque.

If that doesn't fix it, you may be able to use some kind of wicking sealant...Loctite makes some...that could be used on the underside to try and stop the leak.

One thing that can cause this to happen also is a procedure which is shown in the various aftermarket manuals. A piece of tube is cut so that it can be used to drive the rings on the pushrod tube up against the pushrod tube seals to make them seal better. What this does is possibly splits the seals, making a real mess, or pulls the pushrod tube out of the head, starting a leak like you describe.

So you could try the wicking sealant, then replacing the o-rings, and finally remove the heads and replace them.

hargis7556 · Post by **hargis7556** » Sat Jun 13, 2009 10:20 am

Is this a repair that should be taken to my mechanic? I just bought the bike last week you think the shop should take care of it?

schrader7032 · Post by **schrader7032** » Sat Jun 13, 2009 10:48 am

Since it's new to you and not right, I would certainly take it back. Seems like a warranty should be in effect here...oil is not supposed to leak like that. Ask them to figure out what's wrong and see what they say. You're first post about cutting a groove for an o-ring is just not right. The bike was designed properly from the start and if it's leaking in this area, something needs replacing or somethings cracked, etc.

Kurt in S.A.

VBMWMO · Post by **VBMWMO** » Mon Feb 15, 2010 2:52 pm

Ok my right cylooander head is leaking on my foot. Mechanic says they all leak---not buuying that. Also says that a guy in KY cna grind a groove in the heada and place a rbber gasket in the head to stop it from leaking.

Am i missing something or should we just try to put a new gasket and seal it for starters?

Cheer