water in OB gearcase oil??? - The Hull Truth

motoryacht lover · 10-04-2009, 08:40 PM

I have a 2005 40 hp Yamaha 4 stroke OB. When I changed the lower gear case oil I noticed that the oil coming out was not the same color as the oil/gear lube I was putting in. I was using the exact same gear lube from the same can (Quicksilver High Performance Gear Lube). The oil out of the can was an emerald green color whereas the oil coming out of the gear case was an Army Olive Drab like a green olive. That got me thinking if it was water in the gearoil. So I put some in a metal pan and heated it with a torch and the used oil sizzled like you put something in a hot oil deep fryer. The new oil did not do any sizzling. Do I have a problem? Is there a pressure test for this situation? What is most likely the problem and can I do it myself or should I take it to a Yamaha shop? Thank you for your time.

A1 Outboard · 10-05-2009, 04:18 AM

You most likely have water in the gearlube. There are a number of places the water can enter the gearcase. Your dealer can pressure test the gearcase for you to find the leak. Installing new seals involves some disassembly after gearcase removal. The water pump must be removed to replace the driveshaft seal so this would be a good time to service it. Be sure to refill the gearcase with clean oil even if you are not going to service it. An unfilled gearcase that has had water in it will cause the gears and bearings to rust.

motoryacht lover · 10-13-2009, 07:50 PM

Thank you for your response. I took the boat to a yamaha dealer and he presurized the gear case and said it lost no pressure for 15 minutes. He recomends no further testing. Put new oil in and run it. Thought I would update the forum on the outcome.

hwong601 · 05-25-2010, 09:13 AM

i want to repower my 300 2stroke to four stroke can you tell me aprox. cost