Oily Air Box

[San Arthur]

Hi to all.

A few weeks ago I replace the 4 valve guide seals on my 1993 R100GS/PD



After, I went for a long ride.

Next day I found a puddle of oil under the centerstand.



I trace the oil leak to the airbox drain.

When I oponed the box I found a puddle of oil inside. This is a first for me. Oil level is OK.
I clean all them mess and carefully reconnect everything inside.



Why so much oil would come into the air box? Valves, breather valve, rings?

After a short ride last week I found today another puddle.

Any suggestions?

Thanks Arturo

[srankin]

I can see why you are concerned that is a lot of oil where it should not be.

Fill me in on the mileage of the bike? What prompted you to change the valve guides? Have you done any other major work?
Did you do a before compression test and an after one? Did you do a leak down test before and after?

Are you sure you have not overfilled the oil, I know rude, but sometimes the last thing you did can be the problem or lead to a problem. St.

[San Arthur]

Hello and thanks for writing. I replaced the seals, not the valve guides. 45k. Will check oil level again.

[malmac]

From your first photo, you pulled the barrels etc. I suspect you have made a change that is impacting on your crankcase pressure - for example, disturbed rings, broken an oil ring or such. Now the engine is behaving like an exhaust pump, and pushing the oil out past the crankcase breather.

However always hard to say, and even harder when the bike is not in front of me.

All the best with your problem.


Mal

[srankin]

Mal, LOL, I didn't want to write what you wrote, LOL, I am just hoping it is a overfilled oil situation.

Now that subject has been breached. Do a compression test or better a leak down test and see what you get.

On the topic of accidental overfill, I have a funny story from a few years back.
My friend an I had changed the rear main seal on his bike and just put everything back together. I was on the right side of the bike putting the exhaust clamp on and he was on the left putting in the new oil. Suddenly there was an expanding puddle of oil on the lift! I yelled he stopped and both of us went CRAP! So apart came the whole shebang thinking we screwed up the seal. Once the transmission was off, I noticed a trail of fresh oil from the timing hole down the inside of the engine case. It seems my friend was not wearing his glasses was distracted and put the funnel into the timing hole instead of the oil fill.
LOL, it did reenforce our knowledge of rear main seal repair. what to take apart and how. St.

[r67boxer]

From your first photo, you pulled the barrels etc. I suspect you have made a change that is impacting on your crankcase pressure - for example, disturbed rings, broken an oil ring or such. Now the engine is behaving like an exhaust pump, and pushing the oil out past the crankcase breather.

However always hard to say, and even harder when the bike is not in front of me.

All the best with your problem.


Mal

My money is on crankcase pressure or blow back. Had the same happen to my Yanmar 3GM30 diesel engine. Ran fine at idle but shortly after it was run up to 2500 RPM it blew the dipstick 3 m into the air (and decorated the side wall of the garage with said oil). In my case it was glazed cylinders and all that was needed was honing.

Kevin

[toolmandoug]

From your picture, are you missing a bolt between your snorkels in the air box? If memory serves me right, that bolt holds the air box to the transmission and is not a blind hole in the transmission.

[San Arthur]

From your picture, are you missing a bolt between your snorkels in the air box? If memory serves me right, that bolt holds the air box to the transmission and is not a blind hole in the transmission.

Good catch, I was in the process of removing the box for cleaning the oil.

Today was a BSA Gold Star kind of day, a manage to start it, I was able to ride it out of the garage on it’s own power!! And I went for a 1st test ride after replacing the magneto.

Tomorrow I will check oil level, compression and valve clarece.

Thanks for taking the time and answering.

Arthur

[cbclemmens]

Arturo;

The photos show that you removed the jugs but you didn't mention honing the cylinders and replacing the rings. If you didn't, then I am sure that is the source of your problem. New rings "seat" into the cylinder walls, creating microscopic grooves and ridges that they run in. If you pull the rings out and put them back in the rings will "unseat" - meaning these grooves and ridges will not match. Then, as Mal said, the explosion in the cylinder will "blow-by" the rings and push oil out the crankcase vent.

NEVER pull the pistons out of the jugs without honing the bore and replacing the rings.

Craig

[srankin]

Craig, in the photos the pistons are still in the jugs. The wrist pins can be removed from the connecting rods without removing the pistons from the jugs. This is done in a case like this where just the push rod seals need changed. This is to negate the issue of ring wear in.

A note for the future, you do not have to totally remove the jugs, they can be moved far enough away from the block to allow new seals to be inserted and set. Forgive my teflon memory but in this case I don't think the wrist pins need to be removed at all? I could be wrong on this. St.