What is this allen plug

[MPILLIS]

I have found my oil leak on my 1985 R80. There is an allen plug smaller than a dime just below the oil sending sensor on the left lower side of the engine. I had cleaned the bike off so that I could find the leak and after riding about 100 miles I could see it leaking down. This small allen plug is at the same level as the frame making it difficult to get an allen wrench in there to tighten it up. Does anyone know what this plug is and why it started leaking all of a sudden?

[20774]

Could it be your transmission fill plug? That's the only allen plug that's down on that side. Check to see if it's tight...I don't know the torque, but it should at least be snug.

Kurt in S.A.

[The_Veg]

I'll be damned, my bike has that plug too- never noticed it before. It's definitly NOT for the transmission.

BTW, are you the same 'Kurt in S.A.' who posts on Boxerworks? I'll bet somebody there knows what that plug is for.

[cjack]

I'll be damned, my bike has that plug too- never noticed it before. It's definitly NOT for the transmission.

BTW, are you the same 'Kurt in S.A.' who posts on Boxerworks? I'll bet somebody there knows what that plug is for.

When they drill the block oil galleys, they thread and plug the access with a threaded plug. It would have to be tightened a little, or better seal the threads. I think back in the '70s, I had one seep and I cleaned very well with degreaser, dried and painted a tiny bit of epoxy on the thread area. It stayed dry after that.

[Motorman]

When they drill the block oil galleys, they thread and plug the access with a threaded plug. It would have to be tightened a little, or better seal the threads. I think back in the '70s, I had one seep and I cleaned very well with degreaser, dried and painted a tiny bit of epoxy on the thread area. It stayed dry after that.

I no longer have a boxer to look at this plug unfortunately. Is it as flanged plug like the rear end fill point or is it a small threaded plug without a flange that fits flush with the exterior?

In either case I think a better idea to see it would be to pull the plug, clean it and the mating threads of oil then reseat the plug with high temp. thread seal. Be carefull to not get any thread seal on the end of the plug into the case. You don't want it plugging the galley. If there is a flange on it, perhaps a crushable gasket could be used in addition to the thread seal.

[MPILLIS]

ALl ideas sound good and I am going to pull the plug and clean real good and reseal with some red loctite. Someone on another board mentioned using a heat gun on the plug first to loosen the loctite seal already there. Just hope I don't strip that damn plug. Again Thanks all

[lkchris]

"Someone" was Tom Cutter on the Airheads List who's been around BMW since the 1970s and was involved in the successful R90S Superbikes and worked for BMW in dealer training, etc. You cannot get better advice than his, and you ought to follow it to the letter.

[20774]

I'll be damned, my bike has that plug too- never noticed it before. It's definitly NOT for the transmission.

BTW, are you the same 'Kurt in S.A.' who posts on Boxerworks? I'll bet somebody there knows what that plug is for.

Veg, yes one in the same... My initial response was from memory, but I thought there was only one allen plug on that side of the case. I just checked...on my /7, it's not an allen plug, mine's a slotted plug. I seem to recall what others have said that is was part of setting up the oil galleys...

Kurt in S.A.

[MPILLIS]

It is cutter and I went out last night and purchased a heat gun and some metric allen's for my ratchet. Picking up some red loctite at lunch today. Man I just hope I don't strip that plug.
One other question, I know to remove the 2 long bolts on the bottom of the engine front and rear, is there anything on top that has to be removed in order to raise the engine up enough to clear the frame?

[flash412]

One other question, I know to remove the 2 long bolts on the bottom of the engine front and rear, is there anything on top that has to be removed in order to raise the engine up enough to clear the frame?You don't need to remove the front one, only loosen it. You will need to remove some parts of the exhaust in order to raise the rear of the engine. You can remove either the header pipes or the collector box.

Be CAREFUL when jacking up the rear of the motor. Don't jack it right off the centerstand.

[R100RS]

Make sure you are absolutely 100% sure it's not the oil pressure sending unit leaking. I would not tackle that plug if there was a remote chance the sending unit was leaking. I've replaced two leaking sending units and they are much more likely to leak than the plug you are refering to.

[The_Veg]

What Mike said. Cheep'n'easy to replace a sender.

[MPILLIS]

Now you are making me doubt myself and I just got finished draining the oil and changing the filter. tackle the rest in the next day or so. I looked pretty good and made sure what was leaking. I had hoped it was the oil sending unit.
Thanks all

[Friedle]

Another Tom Cutter technique:

Clean everything up real well, REAL WELL, reassemble everything you already took apart, refill the oil and spray the suspected area with an aerosol powder spray (baby powder or even foot powder works well). Go for a ride and reexamine the suspected area. The source of the leak will be obvious and may be something you didn't originally consider, like the pushrod tube seals.

Michael Friedle
Airhead #46
Airheads Beemer Club Board of Directors
many miles on many leaking airheads

[pmdave]

Yes, the little screw in plug is to close off the end of the oil gallery, which is under full pump pressure. Once the plug is installed, there is no need to remove it, assuming your engine hasn't spewed metal shavings into the oil system. IOW, you can use some serious cement when installing it.

I'm assuming you have done your detective work and observed oil leaking from around the gallery plug.

Yes, the little gallery plug (either internal hex or slot) often leaks, but it's no big deal to replace one. The plug is steel and the block is aluminum, and they expand and contract at slightly different rates. I'd vote for getting a new plug, and sealing in place with a good gasket sealer (Permatex or Gaskacinch come to mind). Or, use the high temperature Loctite, since engine heat can be hot enough to warm up the red stuff and allow it to disintegrate.

It's unlikely the plug will strip, since it's lubricated with lots of engine oil. Do let the oil dribble out of the gallery for a couple of hours, then clean the threads with clutch/brake cleaner before installing the new plug. Be careful applying the sealer goop so you don't push it up the oil gallery. Use a Q tip or small screwdriver to coat the threads in the block, and smear an even coat on the plug threads.

pmdave

[MPILLIS]

Ok not sure which loctite to buy , I went to pep boys yesterday and bought some red loctite ($13). Is this the right kind?

[BradfordBenn]

Ok not sure which loctite to buy , I went to pep boys yesterday and bought some red loctite ($13). Is this the right kind?

Probably. Loctite comes in different colors based on how strong you want it. I use Red on my motorcycle. However other stores might be less expensive for the same product. I pay like $5 for mine at the local Ace.

[pmdave]

The "high temperature" Loctite I use is RC/640. There are several versions of the "red" Loctite, but I believe they are all for low temperature applications.

pmdave

[R100RS]

Probably. Loctite comes in different colors based on how strong you want it. I use Red on my motorcycle.
I don't know much about oilheads, but I'd be reluctant to use any more than blue on the motorcycle.

I agree with pmdave that in this situation, red may not be high-temp enough.

[The_Veg]

If this plug never needs to come out again, just JB Weld it. JB can take the temperature.

[BradfordBenn]

I don't know much about oilheads, but I'd be reluctant to use any more than blue on the motorcycle.


That is why leverage was invented, now where is my breaker bar?

Actually I made a mistake, my Blue stuff comes in a Red Bottle.
:banghead

Yup that will make your head hurt.

[Boxerkuh]

When they drill the block oil galleys, they thread and plug the access with a threaded plug. It would have to be tightened a little, or better seal the threads. I think back in the '70s, I had one seep and I cleaned very well with degreaser, dried and painted a tiny bit of epoxy on the thread area. It stayed dry after that.

I called my BMW Master Mechanic today and that is what it is. He stated the following: Clean everything up first, dry it very good and then use baby powder or foot powder and put it everywhere. Then run the engine for about 5 or 10 minutes/miles. Then reexamine the powder. The oil leak will show a black line. If indeed it is the oil galley in the block you will need to move the block around so that you can get to the plug, machanics usually pull the motor or do this when the engine is out of the bike. Take the plug out, clean it and reapply it with a little seam sealer. He said applying anything externally will not work like JB Weld, as the motor pushes about 70 ft/lbs of oil by the plug. He said that the leak can also be one of the push rods or the oil pressure plug, the two of them are in the same proxemity and are much more likely to leak.
Either way, make sure you know where the leak is at first, before you takle this job. Also, know how much oil you are leaking... you may have some time before needing to replace it.... :uhoh

[MPILLIS]

Ok cleaned it up real good and sprayed a bunch of foot powder on the area went for a 50 mile ride and no oil (yet). Snow on the ground so it may be awhile. Thanks guys for all the advice