Bravo I losing gear lube - but where??

jimkari · Oct 5, 2011

I have a '95 Bryant 209 with a 7.4 Bravo I. I've been loosing gear lube slowly for a few years. I never see water in the oil and last year I pulled the drive and replaced the prop seals, the prop shaft bearing housing seal, the seal that mates the lower housing to the upper, the drain pump o-rings, the seals that go between the outdrive and the gimbal housing, as well as the seal that goes under the top cover of the shift housing. I never see any oil leaking inside the boat or out, but I seem to lose about 3/4 of the reservoir throughout the summer. I just tried pressure testing the outdrive and it's been holding a steady 12 lbs for the last two hours. I am really stumped.

Please, please share your advice.

Thanks,

Jim

boattoy · Oct 5, 2011

Re: Bravo I losing gear lube - but wear??

Re: Bravo I losing gear lube - but wear??

your testing pressure without any gear oil in drive correct? if its holding pressure i would focus on everything that contains gear oil that's not in the drive. also try turning the drive with it in gear to see if it releases the pressure.

jimkari · Oct 5, 2011

Re: Bravo I losing gear lube - but wear??

Re: Bravo I losing gear lube - but wear??

Thanks for the quick reply. Yep based on the advice posted on the forum, I drained the oil first and then pressure tested. I installed the lower drain plug and pressure tested through the vent hole. I did not pull the drive or block off the reservoir. I wasn't sure if it would hold pressure due to the vent in the cap, but it does. When I tried squeezing the reservoir bottle it clearly had pressure in it. I am really stumped. I know there is a chance the oil dropped due to air in the system, but that seems like a lot.

jimkari · Oct 5, 2011

Re: Bravo I losing gear lube - but wear??

Re: Bravo I losing gear lube - but wear??

Also I did try spinning the prop shaft. I haven't tried turning over the engine with it in gear. I'd probably need to bypass the neutral safety.

boattoy · Oct 6, 2011

Re: Bravo I losing gear lube - but wear??

Re: Bravo I losing gear lube - but wear??

Make sure it can't start. Just to eliminate the possibility of something being out of round and causing oil seal to open up a little

HT32BSX115 · Oct 6, 2011

Re: Bravo I losing gear lube - but wear??

Re: Bravo I losing gear lube - but wear??

Bravo I losing gear lube - but wear??

It's either a seal or the drive lube monitor reservoir hose, or fittings etc, but it should cause any additional wear if you keep it full.

If you changed the oil it will drop quite a bit for a while as air bubbles etc work their way to the top

Brew2 · Oct 7, 2011

Re: Bravo I losing gear lube - but wear??

Re: Bravo I losing gear lube - but wear??

I had the identical issue with my alpha drive last season and went through all the steps you have outlined above. I came to the same conclusion I think you are coming to ... it must be air in the system.

Never did see any evidence of oil in or outside the boat. This season, the oil level dropped, but not as much. Probably 1/2 inch in the resevoir. It was earlier in the season though and things seemed to stay at the same level for the remainder of the season, so I'm pretty much convinced it was air trapped somewhere in the system that worked it's way to the top.

Good luck!

HT32BSX115 · Oct 7, 2011

Re: Bravo I losing gear lube - but wear??

Re: Bravo I losing gear lube - but wear??

Mine dropped quite a bit over 20 or 30 hrs of running after I changed oil the last time.

I kept topping the reservoir off and level eventually stopped dropping.

The Bravo is a big drive and there's a fair amount of places for bubbles to hide......

tpenfield · Oct 7, 2011

Re: Bravo I losing gear lube - but wear??

Re: Bravo I losing gear lube - but wear??

I used to loose a lot of oil from the outdrive reservior, because there were hairline cracks developing in the bottle. The oil was collecting in an area of the hull and then slowly making its way into the bilge.

Since I replaced the bottle, no more oil into the bilge, but I still seem to loose some oil with no appearant sign. I figure that maybe during use air gets pushed up from the outdrive and into the reservior. Then, went things cool down, more oil gets pulled into the outdrive. this process would eventually fill the outdrive completely, thus no more air to purge. who knows.

As long as it is not prodcuing visible signs, or loosing too much, I'm good.

jimkari · Oct 7, 2011

Re: Bravo I losing gear lube - but where??

Thanks for all the advice. It's got to be air in the system. It held 12 lbs of pressure for 24 hours without any fluctuation even when I spun the prop shaft and cranked over the engine. I'll fill it up again and keep an eye on it.

I pump the fluid in from the bottom until it comes out the vent hole and then install the vent screw and fill the rest from the reservoir. Do you guys do the same thing or due you fill the entire drive and reservoir from the drain plug using the pump. I suspect I get air into the system doing it this way but I thought I read that the way to fill the drive. Thoughts??

Thanks again,

Jim

Scott Danforth · Oct 7, 2011

Re: Bravo I losing gear lube - but where??

I fill the system, including the reservoir by filling from the drain. this way there is no air in the reservoir line

jimkari · Oct 8, 2011

Re: Bravo I losing gear lube - but where??

Thanks for the thoughts. I think I will try it that way when I fill it again.

Jim

Bravo I losing gear lube - but where??

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