diagnose water in oil and cyl in a 3.0 140

[jschick]

I picked up a cheap project boat and got it home this AM, a 89 wellcraft with a mercruiser 140 3.0. I bought it knowing their is water in the oil, the oil is milky but not slimmy. I also pulled the plugs adn cyl #2 from the front has water in it. I also pulled the manifold and it was full of water. lots of water in the exhaust side. I dried the manifold and have it full of water now so far is is dry and no leaks after 1hr of sitting.
compression is 125 125 135 135, oil level is about 1 inch over full on the dipstick, so it probably has 1 to 1.5qts of water in the oil.

so what does all this mean? cracked block? if cracked block how does the water get in the cyl. and if the manifold is cracked shouldn't more then one cyl have water?

 

[Gary H NC]

Re: diagnose water in oil and cyl in a 3.0 140

Sounds like you bought a cracked block and manifolds..
I hope you realized going into that purchase the engine will need replaced..
Good luck..

 

[havasuboatman]

Re: diagnose water in oil and cyl in a 3.0 140

A cheap boat? No such thing.
Gary is probably right about needing a new block.
But using water to find a leak in a cold manifold doesn't always work. If it's a small crack, and depending where it is, it may only leak when the manifold is hot.

 

[jschick]

Re: diagnose water in oil and cyl in a 3.0 140

well manifold sat all night and the water level might be down a tad but no water in the exhaust side, it's dry. I bought the boat with the assumption I would put a new engine in it, but the boat quit running the end of last year and then was winterized and was not looked till this spring. the past owner was told by the marina it need a new engine but that's it. I would really like to understand what the problem is and not just replace the engine because that's it!
at this point I would think a cracked head makes much more sense then a bad block. the boat quit running while on the lake, so getting water in the cyl makes since here. but the compression although lower in 2 cyls, it should run with the readings I got. also their is a lot of oil covering the engine, but this could be from winterizing. the engine bay is absolutly spotles. so winterizing oil makes sense.
I will probably pull the head and take a look, unless someone talks me out of it, am I way off track here? I only have water in 1cyl and it was a lot of water, so it makes sence to me that it could get to the oil from leakdown. or blowby or if the head is cracked depending where.
thanks any info to help me understand? but I don't see how a cracked block would put water in the cyl and still have compression?

 

[Don S]

Re: diagnose water in oil and cyl in a 3.0 140

The block is probably cracked internally. When water flows through the cooling system, it leaks into the oil pan.
Drain the engine blocks cooling system and isolate it from the exhaust manifold and pressure check the block. It should hold pressure.

 

[ken_23434]

Re: diagnose water in oil and cyl in a 3.0 140

This is a comment to the whole community...

Couldn't it be as simple as the exhaust flapper not doing it's job? Maybe the boat was in the water, hit by a wave at the rear, the water flowed up the exhaust into the cylinder that was in it's exhaust cycle when the motor was shut off (so it's exhaust valve was open). Water filled that cylinder, slowly leaked by piston rings ending up into the oil pan?

I am not trying to get your hopes up with a really simple fix...

I was in your situation a couple years ago, late 80's Wellcraft with a 3.0 that needed replacement. Luckily, I got an engine of Ebay that actually was "as advertised".

 

[jschick]

Re: diagnose water in oil and cyl in a 3.0 140

if I pressure test the system, I assume it will loose pressure if the block is cracked or if the head is cracked, so I would still be at the same place I am now right?
I appoligize but I would like some more info as to the theory? water in only 1 cyl?