I changed my gearbox oil as it looked awful, since the change when you look through the sight glass it's clear but once running goes cloudy/milky then once left it returns back to clear now I'm unsure if there is water in there or not haven't noticed coolant levels drop? Or once settling is the oil and water separating hence the clear look.

It's a 2003 txt pro 280 many thanks

What oil are you using?

Pj1 sae75w ultralight that's what the local trial shop recommended

magh

I've had similar recently but the oil didn't turn clear again, this could just be related to the brand of oil or even the coolant.

There's three possible sources of water seepage into the gearbox.

1. Cyl head o-rings
   
2. Water pump impeller seal
   
3. Pressure washing in the wrong places.
   

Undisturbed, the cyl head O-rings rarely fail, the water pump seal however does have a bit of history.

I changed the milky oil in mine twice and ran the bike for 10 hours+ in between. During this the water level didn't drop enough to cause a problem.

Fact is that the seal is reasonably cheap, is difficult to prove categorically and doesn't need any specialist tools so might be worth doing anyway.

There's a good video on Jim Snell's Trials Parts USA website.

Sometimes the seal wears a groove into the impeller shaft. Mine didn't need a new shaft, I just polished it up with some ultra fine Wet'n'dry.

3/4 hour job, worth doing if you suspect it. Job done

Dom

Are you sure it is not just "frothy"? being churned around gears and a clutch doing a few thousand revs per minute will whip it up in no time.

See that's what I am suspecting I don't know the history and only changed the oil once and the little 90degree bend and breather pipe were missing when I got then bike so water may have got in.

Think ill change it a second time and see how it goes.

My thought are either yes it's frothing up from the gears or its the water displacing from the oil hence returning clear.

in the past 48 yrs i have changed oil X times ...always white! I assumed it was ally particles from the casings as a silver sludge settled out after a few hours leaving clear oil above...maybe from the plain plates in clutch? never had problem.....btw many of these bikes (most) were air cooled!

I just started to use the same oil in my bike...it does seem to get frothy...if it doesnt turn clear after it's shut off for a while and still looks milky you may have an issue...mine has a fresh topend and a rebuilt water pump and there is no coolant getting in the gearbox but looks kind of milky when running..so far it always clears up...I have gotten water in the gearbox before on my enduro bikes and the oil does not clear up once it's contaminated.

Edited May 10, 201313 yr by squid_on_a_300