Bravo 3 lower unit lube reservoir pressure leak question

[ScubaDave16]

I have a 2001 Maxum SCR 2900 with a Bravo 3 and 7.4L. I notice blue oil smoke coming from the engine compartment after any run at 3500-4000 rpm for maybe 10-15 min or more. I figured out the lower unit lube reservoir is dripping onto the exhaust manifold. I could see lube leaking out of the cap and the reservoir which had been at the full line while cold was now completely full. I changed the cap with a new one but still get leakage. I also see a slight oil sheen around the outdrive. I keep the boat in the water and have no trailer so impossible to drain and check the lower unit lube but it does appear foamy at the top of the reservoir. So I have read that this might be due to a leak in the lower unit. Other posts seem to indicate that some oil expansion is normal. I was under the impression that the 80/90 weight oil did not expand unless there is extreme heat or water vapor in there. I felt the lower outdrive but the water is 50F so of course it was cold too.

except for the oil smoke the boat seems to run fine except for a loud hissing at cruising speed which is probably not related.

pulling the boat will be difficult and expensive and most of the mechanics in the area are booked out until July anyway.

my question is how bad is this? am i damaging the outdrive by running the boat if there is still lube in the reservoir? what should my next step be?

Thanks for any advice on this.

[mmwjr]

It’s normal for the gear lube to expand some as the gear case gets hot internally. Foamy lube is not a good sign nor is the sheen on the water, most likely there is a leak which is letting water in. This can damage if not destroy the gears. I would have a short pull done to drain the lube to determine how much water is in it. If not bad refill and relaunch but get on the schedule to have the drive resealed.

[ScubaDave16]

so I went back to the boat today. after all had cooled off I checked the lower unit lube reservoir. it LOOKS perfectly normal now. nice dark blue green color. I dipped a rag in and it smells and looks like normal. so my question is... would water show up there and give the classic milky appearance or would that only be down in the lower unit itself. Is the fluid in the reservoir pretty representative of the whole system? I have had water in the lube in other boats and it is pretty milky. I see none of that. yesterday there was some foamy looking stuff on the surface but sadly i didn't take a sample.

If this was simply a matter of pulling the boat out on a trailer and draining a bit of lube i would say no big deal, but the boat yard wants $750 to pull out the boat and won't even look at it until mid July.

is there any way to check the lower unit lube without pulling the boat?

if there is no milky oil in the reservoir how "bad" would it be to just run the boat slowly until the fall when it will be in the boat yard anyway. of course I don't want to damage the outdrive permanantly, but we only have a 3 month season here and i hate to miss it.

[mmwjr]

Water is heavier than oil so you could have water in the lower end that won’t show in the reservoir. Considering the cost of the drive I would pull the boat. I’m not impressed that the marina can’t work a short haul in before July. Did you tell them you’ll willing to come during a week day?