Oil foaming inside gearbox?

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
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Southern Airboat Member
Posts: 81
Joined: Sat Jun 23, 2007 2:34 pm

Oil foaming inside gearbox?

Post by STINGER477 »

Just finished rebuilding my K-Way gearbox,(new bearings and seals). I also installed a sight glass so that one quart of gear oil can be seen at the half-way mark in the glass. I put the box back on the boat an test ran with no prop for couple a minutes up to about 3000 engine rpm and noticed that the oil in the sight glass seemed to be foaming. I did change oil brands, it had rotator oil in it and I changed to Lucas 85-140. Anybody know if this is normal? I had heard that when you get a foaming gear oil that it causes premature wear on the seals.
Southern Airboat Member
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Joined: Mon Aug 16, 2010 11:09 pm

Re: Oil foaming inside gearbox?

Post by Dirty1 »

automotive gear oils are designed to foam, thats how the oil gets down the tubes to the wheel bearings. you need to find a gear case oil from like mercruiser or volvo penta.
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