'89 4.3L Merc - water & oil in bilge

[b.shaw]

Hi All,

I'm new here - found the forum searching for rebuild instructions for my 4.3L Mercruiser. I am pretty experienced with cars but have not worked on the boat much.

I've owned the boat since new, a 17' 1988 Larsen bowrider with 4.3L Mercruiser I/O. It's been a blast and relatively maintenance free since I bought it. The last couple of times I've been out on the CT River I've had water and chocolate milkshake oil in the bilge. I don't have water in the engine oil, the engine oil is OK. I do see a little oil at the rear of the boat where the water exits.

I've never seen this in the 21 years I've owned it. Is this a common failure mode? It looks maybe like the head gasket is failing and blowing some oil into the cooling water and also out of the engine?

Anyways, I'm thinking my ski season is done, and am looking for suggestions on where to get parts like gaskets. Also, anyone have a web site showing details of rebuilding one of these?

Thanks,

Bill
http://b.shaw.home.comcast.net/Daytona

 

[cr2k]

Re: '89 4.3L Merc - water & oil in bilge

I am guess your front seal is gone on your out drive and water is mixing with oil in the drive and exiting through the bellows and in to the boat.

There is no such thing as a maintenance free boat. You can pay as you go and keep it up, or like you are about to do... pay it all at once.

If my guess is right you are looking are looking at upper drive re seal, gimbal bearing, u-joints and bellows at minimum. While you are at it, have the lower re sealed and the impeller replaced. Then start saving for the next big "gotcha".

 

[Bondo]

Re: '89 4.3L Merc - water & oil in bilge

Ayuh,... Before you go buying Parts,.... Find the leak 1st....

It looks maybe like the head gasket is failing and blowing some oil into the cooling water and also out of the engine?

That's pretty much Impossible..... I though you know your way around a Motor,..??

 

[b.shaw]

Re: '89 4.3L Merc - water & oil in bilge

I just checked the drive oil - should have done that first - chocolate milkshake. It's draining now.

Thanks,

Bill

 

[b.shaw]

Re: '89 4.3L Merc - water & oil in bilge

Found a hole in the bellows and chocolate milk in there, too.

Is the water leaking in the bellows getting into the drive, or do I have another leak somewhere?

 

[45Auto]

Re: '89 4.3L Merc - water & oil in bilge

The leaking bellows rusted the input yoke to the outdrive. The rusted yoke then trashed your upper seal in the outdrive. This allowed the outdrive to suck in the water from the leaking bellows and blow the "milkshake" out.

Good example of why you should change your bellows every few years.

 

[Don S]

Re: '89 4.3L Merc - water & oil in bilge

The leaking bellows rusted the input yoke to the outdrive. The rusted yoke then trashed your upper seal in the outdrive. This allowed the outdrive to suck in the water from the leaking bellows and blow the "milkshake" out.

Good example of why you should change your bellows every few years.

Then the milky mass goes through the hole in the gimbal housing and into the bilge.

I've owned the boat since new, a 17' 1988 Larsen bowrider with 4.3L Mercruiser I/O. It's been a blast and relatively maintenance free since I bought it.

It shouldn't have been that maintenance free.
Go up to the top of this forum to the Adults only sticky, there are OEM service manual downloads there, along with a lot of other information you should read.
Find your owners manual and have a look at the maintenance schedule.