Too much oil in transmission, what is the cause?

[kheerema]

I'm just doing my spring tune up/fluid checks, I popped the transmission fill up plug out, and to my surprise, some oil came out, not a whole lot, but I know I didn't overfill last year.

Should I be concerned? I had a bad rear main seal, but I had that replaced last year along with a new clutch. NOt sure if that has anything to do with it?

[Isamemon]

what is your engine oil doing, has or was it low
was the bike level when you filled it last time
is the oil color correct adn not milky, if a little milky looking then maybe the grommet at the speedo cable is shot and allowing water into the tranny...not a good thing
I would suspect the rear main seal
good luck

[kheerema]

The oil color was correct, no water. It smelled like the proper stank of gear oil.

I just checked the oil level, and I'm at the 1 qt. low mark. I know I put some more in not too long ago.

I just had the rear main seal replaced last year, I can't believe I have to do this over again.

A PO put a lightened flywheel in, is this the cause? Should I just leave the oil level at the 1qt. low mark? I'll have to search for oil level posts on these bikes, I know everytime I filled to the full mark I just ended up burning oil I think or something...it never wanted to stay at that full level...I think theres some info out there.

I have a 1k mile trip planned next week to Big Bend Nat'l park. This bike has never broken down on me, should I still plan on the trip?

[20774]

Kevin -

No way engine oil can get into the transmission. It has to come out of the rear main seal, migrate around the spinning clutch, and then force its way past the seal on the input shaft. Can't happen.... And the clutch doesn't have anything to do with it either.

Have you checked the quantity of oil in the final drive and driveshaft? That's the only place gear oil can come from. It is possible for the oil to migrate forward.

Did you filled the tranny properly before? Bike on centerstand, oil pushed into the fill port so that oil is just even with the bottom of the hole.

Also be sure the tranny bolt holding down the battery negative cable has the hole in the middle open. This allows the tranny to "breathe" as the oil heats up and cools down.

I would reservice the entire drive train, putting in the correct amount of oil. Then go on your trip. Have fun and recheck when you get back.

[benway]

+1 on what Kurt said

[ebeeby]

Wait a minute.

I am getting this right?

topic 1, transmission:

It is next to impossible for gear oil to migrate forward from the swingarm. In fact it is impossible unless you overfilled the swingarm by 16 ounces and park the bike vertically, forks down. That said, it is possible to force water in through the grounding strap bolt breather hole - if - you use a power washer which you should never do on an airhead. My guess is that the bike had the rear wheel touching the floor when you filled the gearbox and front wheel touching the floor when you checked the level or that you've had an earthquake and your garage floor is no longer level.

topic 2, engine oil :

1 quart low?????!!!??? How many quarts fo you think this engine holds?
You *must* check the oil level more frequently than to allow it to fall to one quart low. In fact, you should check it everytime you put gas in it - unless you have a known leak in which case you must check it yet more frequestly.


(rant mode off)

[kbasa]

+1 on what Kurt said

+2

[Boxerkuh]

+2

+3 :thumb

[widebmw]

1qt low mark :scratch
On my R80 and my R100R the low oil mark on the dipstick was less than a 1/2 qt
from the full mark. If you put 1qt in, it will be way over filled.

[lostboy]

It is common for these bikes to transfer oil from the driveshaft into the gearbox. The seal at the gearbox output flange can leak. There is also a tiny vent just above the seal to vent the driveshaft. If there's too much oil in the swingarm (more than 80 cc, no matter what the manual says) or the shock springs inadequate, oil will transfer.

All stock R90s consume motor oil. Replacing the rings with aftermarket ones helps, as will using a '76 and up, or a good 3 quart pan, along with a later dipstick, which has it's marks placed lower. You'll have to modify your centerstand to clear the OEM pans unless you have a Reynolds stand.

[Isamemon]

ok
1 qt low, on these old scooters is not a good thing, since oil and air is all that keeps them "cool"
if this is common for your bike, then either carry a gallon of oil with you , or find the leak and fix it
if you dont wan tto fix it, and if your using the cheepest oil you can find, then some of those do break down fast and vaporise
if your using the cheepest oil you can find, then start riding a throw away bike , if your going that cheep you should not be on a BMW, but maybe an old honda or yamahammer

[DarkCloud]

Haven't been pressure washing the bike? JON