Ok, the suck bucket comes in handy once again. Boss wanted me to check out a Cat 963 we've had on the yard for some time, just haven't had a chance to get to it. While checking fluids, I pulled the dipstick for the transmission drive unit (fill pipe on left) and noticed it was overfull. Didn't think a great deal about it at the moment, oil was clean and clear, figured someone overfilled it because you couldn't really see it good on the dipstick. Then I noticed the sight glass on hydrostat drive didn't have any oil showing in sight glass. Proceeded to pour oil into hydrostat unit (fill pipe on right) until it was up to level. Then, I noticed it was slowly going down. What! Tell me it ain't so!
Grabbed the suck bucket, stuck hose down the fill pipe for tranny drive unit, sucked out 3 1/2 to 4 gal of oil in moments.
Stuck dipstick down tube, noted oil level. Waited a few moments, checked again, oil level had risen on dipstick. Waited a few moments, check again, continued to rise. Did this several times, oil level kept rising in tranny drive unit. Not good. Came to two conclusions; 1) probable shaft seal failure between tranny drive unit and hydrostat drive unit allowing migration of oil between the two, not good, big project, and 2) hey, at least the suck bucket works good!