Oil in the bilge

[airman1094]

Took my old boat out for the first time since I owned it...5+ years. Kept taking on enough water to pump the bilge every 5 mins or so...only was taking on water when the boat was in motion and the stern was lower in water. It was last night. Couldn't find where water was coming in from. This morning I noticed oil in the bilge. Not a happy sight. I can't find an oil leak anywhere. Some of my water was coming from the rubber boot between exhaust riser and exhaust tube headed to the bellows. My thoughts are maybe the oil is coming from there via a bad head gasket maybe? I just know thetmore the engine was revving and more the bow was up more water came in. Maybe the drive bellows have a pretty good leak in in it and some oil was being washed in from there. I'm stumped. And disappointed. I have a mercruiser 120 and a pre alpha stern drive. What do you guys think? I'm debating just getting rid of this thing.

 

[Bt Doctur]

pull the drive to inspect for water

 

[Rick Stephens]

Sounds like it needs a good going through. I would not be so much disappointed as curious to know where the leaks are. I would also suggest that expecting your boat to float without maintenance trouble after sitting for 5 years is a stretch, even for a newer boat. You don't describe what you did to prepare for its first outing, but if asked, I would have recommended pulling the drive, changing the fluids in drive and motor, checking impeller, lubing u-joints and gimbal bearing and doing a very close inspection of bellows. Then change the engine oil, oil filter and especially fuel filters. Then after everything checked out, run it in the driveway on muffs to make sure. Boats require effort to maintain.

 

[airman1094]

I had replaced the bellows, changed oil and filter, fuel filter, water pump replaced and some other stuff. Thought it was about ready. Ran it on muffs a few times and no issues noted

 

[Rick Stephens]

If the bellows is fine, then maybe the transom is soft enough that it is leaking around the gimbal housing. You might have someone stand on it and see if they can make it move against the transom when they bounce on it a bit. No worries that it will damage things, they are designed to push the boat at high horsepower, same drive up to 300 HP hanging on other side.

 

[airman1094]

Haha I'm 350 lbs and put my weight on it and it don't move.

 

[airman1094]

So I noticed there is less oil in the pan then there was the other day before I hit the water...but doesn't seem milky like if water is mixed in...now I'm confused

 

[Rick Stephens]

An oil leak is a separate issue entirely from taking on water. Oil can leak from darn near anywhere... rear main, end plug on the oil gallery, rocker cover, front main, pan gasket, timing gear cover, fuel pump, distributor. You'll need to track it down. Start out by cleaning everything then running it until you find the leak. No magic to be had there.

Water coming in when under way is always interesting. There is a seal on the top of the pivot pin inside the top of the gimbal housing. On older merc gimbal housings there's a grease fitting there as well.

The gimbal housing itself has a funky round foam seal between it and the transom. Age and/or soft transom wood can cause it to leak at any place around.

There's a water hose going to a through hull fitting in the top of the gimbal housing. That tube has a rubber grommet on it that can crack or even fall apart.

The water hose itself going from bell housing to engine can crack. This one will usually show up when on muffs in the driveway.

Another one that shows on muffs usually is a exhaust pipe that has corroded through.

Only thing I can think of to test doesn't even require you to take the boat off a trailer. Back in until the stern is as deep as it goes and crawl under and start looking. Use your cell phone camera to video the transom area to see if you can find the trickle before even starting up. Take a mirror with you. Whatever it takes.

 

[airman1094]

I'm gonna try just backing it in to see where the water leak is. As far as the oil leak goes...I think I've narrowed it down to either rear main seal or oil pan gasket. More details to follow when I know more...but by the looks of it I'll be rebuilding this motor. I'm sure it needs it anyway. While I have it out of the boat I might as well give it a full rebuild. It's still original parts and seals to my knowledge. While motor is out I'll also pull the gimbal off and get a new seal for that as well. If the transom is too soft I'll relpace it as well. Wouldn't be the first transom I've had to replace.

 

[Scott Danforth]

I would look for a good 3.0 / Alpha 1G2 vs rebuilding the 2.5 liter you should be able to get a good motor and drive for about what it would cost you to rebuild the 2.5 liter.

 

[airman1094]

Good news...no oil leak. I just realized I didn't prime the oil filter...that's where my oil went. As far as the leak I found it...the lower exhaust boot is leaking badly. I believe the oil in the bilge was residual washed off somewhere near that leak...as it's not coming from the engine.

 

[Grub54891]

Good news...no oil leak. I just realized I didn't prime the oil filter...that's where my oil went. As far as the leak I found it...the lower exhaust boot is leaking badly. I believe the oil in the bilge was residual washed off somewhere near that leak...as it's not coming from the engine.

If there is oil in the bilge, there is a leak. The exhaust boot only has water and exhaust flowing through it.