Oil increasing in oil tank Rotax 912ULS

Re: Oil increasing in oil tank Rotax 912ULS

by Rob Seaton » 9 years ago

Rob Seaton

3 1.32k 251

Good reality check Alan.
Not sure if this has been mentioned in this string; the fuel pump is another likely cause of a fuel in-the-oil problem.
If the pump shaft seal and the diaphragm break down the fuel has a path to the inside of the gearbox. This is more likely if the fuel pump is very old.

Pumpcut-away.jpg (You do not have access to download this file.)

Re: Oil increasing in oil tank Rotax 912ULS

by Conrad Beale » 9 years ago

Conrad Beale

3 66 22

Rob,
Are you sure the source can be from the fuel pump? I thought all the pumps have a drain between the diaphragm & the shaft seal. If the diaphragm is damaged fuel will come out of the drain, likewise if the shaft seal is leaking the oil will come out the drain.
Both the crankcase & fuel supply are at positive pressure so any fluid leaks will naturally come out the drain on the pump.

Re: Oil increasing in oil tank Rotax 912ULS

by Rob Seaton » 9 years ago

Rob Seaton

3 1.32k 251

for sure, we had a couple of situations where the fuel was coming from the pump. That was on the old Pierburg pumps though; it had weep holes, but no low point drain like the new corona pump.

Re: Oil increasing in oil tank Rotax 912ULS

by Roger Lee » 9 years ago

Roger Lee

131 5.38k 5.44k

Send an oil sample in for testing. That will remove any doubt.

---

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

Re: Oil increasing in oil tank Rotax 912ULS

by Lloyd KAY » 9 years ago

Lloyd KAY

1 2 0

Hi Roger,
Not from fuel pump, cant get in from there, vent holes between diaphragm and gear box.
I did a very scientific test, poured equal amounts of two samples on concrete in the sun, one evaporated away quickly and left no trace, the other evaporated slower and left a stain, which eventually disappeared.
My supplier has pumped out the fuel tank and a fresh drop has been made. They have sent samples in for testing, will be interesting to see what the outcome is, diesel I suspect. As you mentioned.
Cheers.