More water in the oil...

[ferg]

Hey everybody, I'm new here and I have a few questions for anyone that is willing to help. I have a MerCruiser 165hp (GM I-6 250cid) in a '75 Cobalt 17'. I'm fairly new to boating, so bear with me. Anyway, I ran my boat about 6 times last summer and had no major problems until the prop ate an inner tube. Yeah I'm an idiot. Since then, I brought the boat into the shop to have the shift cable changed out...they changed the cable and then told me that I had water in the oil. So I bring it back home and drain the oil, and out comes a grayish oily mixture...which I assume is what water in the oil is (although I didn't think oil and water generally mixed).

So my question here is, what do I do? Again, I'm not very familiar with boat engines, but I have done some work on similar car engines. It is my understanding that there are tons of reasons why I might be getting water in the oil. I know that the head gasket or manifold might be busted, the block might be cracked (I found no external cracks), the oil pan gasket might be bad (but no leaking oil), water might be getting into the carb somehow, etc etc yada yada...

I am more than willing to (in fact planning on) take the motor out and start ripping it apart, and I know that it may end up costing more than it's worth, but I don't have the money for the shop to search for a problem. So, what should I start looking for before I take the motor out? And if I do end up taking the motor out, what would be the recommended course of action?

Basically, I need a laundry list of crap to look for, if anyone is up to it. If any other people are like me and kind of new to boats, they'll probably also appreciate a response to this, as it seems really difficult to get good information. I've read many threads in this forum about oil/water problems, but they don't usually seem to have all of the information I'm looking for.

Thanks guys.

 

[Haut Medoc]

Re: More water in the oil...

Welcome to iboats....
Was it properly winterized?
Block drained?
Was the water intrusion at the end of last season?
​

 

[ferg]

Re: More water in the oil...

Funny you should ask. I don't think it was properly winterized, which is my fault, because I'm dumb. I drained the intake/exhaust manifold and could not find any other drain plugs. HOWEVER, I haven't actually taken the boat out since winter, so this problem began occurring prior the any freezing problems (not to say that there isn't any new freeze damage..)

I don't know if wrapping the tube around the prop had anything to do with it, but it never seemed to run quite right after that. It had also been in to the shop twice last season before that and they never mentioned any 'water in the oil' problems.

 

[Haut Medoc]

Re: More water in the oil...

Well if you did not drain the block itself & you live in a climate with freezing temps, that ain't good......
I would get a compressor, pull the riser, & block off the water outlet....
Disconnect the hose that feeds the engine water, if you have power steering, you can disconnect it at the cooler....
Introduce pressurized air into that hose & listen......
If there is a crack, you will hear air escaping.......
You might as well do this test first......
If the block is good, we will proceed from there......​

 

[WillyBWright]

Re: More water in the oil...

The water in the oil probably came from the block. It leaked out of the cooling cavity through a crack and dribbled down into the oil pan. When the motor was started this spring, it mixed to gether. Until then, the water was sitting below the oil since oil floats on water. It'll eventually separate back out of the oil. Not that it'sa going to help. I'm afraid you need a new motor.

 

[ziggy]

Re: More water in the oil...

this read might be helpfull.....

http://www.boatfix.com/merc/Bullet/01/01_10.pdf

http://www.boatfix.com/merc/Bullet/01/01_13.pdf

helped me when i had some water in my oil anyways......

 

[ferg]

Re: More water in the oil...

Well if you did not drain the block itself & you live in a climate with freezing temps, that ain't good......
I would get a compressor, pull the riser, & block off the water outlet....
Disconnect the hose that feeds the engine water, if you have power steering, you can disconnect it at the cooler....
Introduce pressurized air into that hose & listen......
If there is a crack, you will hear air escaping.......
You might as well do this test first......
If the block is good, we will proceed from there......​

First, I'll try to figure out how to do what you said to do, and then I'll do it. I'll get back on my results.

 

[dvan1901]

Re: More water in the oil...

Other's will come along with specifics, but you can run a pressure test and listen for the leak. If you didn't winterize (going on my own current experience here) you could pull the inake manifold and look for the crack. It's probably got a rust spot on it where it's coming out. Look at the intake manifold iteself when you take it off for cracks as well. If you are lucky, it's just the manifold, if you are unlucky (like me) the block is cracked and will need to be replaced.

 

[ferg]

Re: More water in the oil...

The water in the oil probably came from the block. It leaked out of the cooling cavity through a crack and dribbled down into the oil pan. When the motor was started this spring, it mixed to gether. Until then, the water was sitting below the oil since oil floats on water. It'll eventually separate back out of the oil. Not that it'sa going to help. I'm afraid you need a new motor.

I don't know if it matters all that much, but I haven't started the motor yet this spring. The problem began before any freezing occurred. But you're probably correct about the new motor thing, which sucks, because I think I'm the poorest boat owner this side of mason dixon.

 

[ferg]

Re: More water in the oil...

this read might be helpfull.....

http://www.boatfix.com/merc/Bullet/01/01_10.pdf

http://www.boatfix.com/merc/Bullet/01/01_13.pdf

helped me when i had some water in my oil anyways......

A couple decent reads. Actually I just think you should come over and give me a hand .... considering you and I share the same lake.

 

[ferg]

Re: More water in the oil...

Is there a difference between the cylinder block water drain and the drain plug on the intake manifold?

 

[ziggy]

Re: More water in the oil...

there's three drain plugs on yer L6. one on the underside of yer manifold at the back. below that, on the block is the block drain. yes it's different than the manifold drain..both my L6's have had a t valve that ya unscrew to drain the block. there's also one on the back of the riser. all my drains are on the port side....
you've got pm......

 

[ferg]

Re: More water in the oil...

I found the block drain plug....and I'm pretty well convinced that the water problem I had at the end of last season is likely worse now.

Anyway, I'm in the process of removing the manifold and am having serious trouble removing what I think is the exhaust hose from where it is clamped underneath the transom mount. The hose leads from the bottom of what I think is the thermostat housing, is clamped to the manifold in two places, then appears to lead out of the boat....except I can't get that damn hose off! Any advice?

 

[ziggy]

Re: More water in the oil...

two hoses going to the back. one off the riser. it's 3-4" in dia. that's the exhust one. the smaller one i think yer talkin about comes from the transmom shield. there's a nipple there and the hose slides ontoit. that hose goes directly up to the tstat houseing. that's the main water feed for everything. to get it off that nipple way down in the back. slit the hose leanthwise with a sharp knife. ya gotta ruin an inch or so of hose. but i bet thats the only way it'll come off. unless ya break off the nipple attached to the transom shield.........use a sharp knife, it'll cooperate......

 

[ferg]

Re: More water in the oil...

So I ended up leaving the water supply hose attached to the nipple and instead just removed the mounting bolts from the manifold and the clamp from the thermostat housing. Anyway...i got the manifold off, and the problem was revealed. 6-8" horizontal crack directly underneath the manifold gasket. Guess I need a new block. What a bummer.

 

[ziggy]

Re: More water in the oil...

i'm thinkin external cracks can be repaired, internal cracks can not be repaired. however. i'm under the impression that ya left the water in it to long and may have internal engine damage. i'd check into that a bit before spendin any money on crack repair. i don't know how long ya can leave watein in a block and still save it w/o a rebuild. from that mercruiser service bullitin. it don't sound like to long. ya might call waldron machine & welding. i never had him work on my engine. but he showed me a couple external cracks that he'd repaired and ya couldn't even see the cracks. he said he stood behind his work too. and he was a nice fella too....some folks use some jb weld or the likes here on the fourm too. or marinetex maybe, i don't know. others might though. try searchin about cracked blocks on the fourm and see what ya can find out maybe.....bummer about yer bad news......