OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

[Surfly]

OK, I knew I'd have to put some money in this boat. Mechanic says compression is very good on all cylinders and it runs great, but small amount of water showed up in the oil. He thinks it's risers or manifolds but can't be sure without tear-down. He also says he can't be sure whether water has been in oil long enough to damage bearings etc.
The boat is a '94 with OMC '93 outdrive that he claims is in very good shape. The boat has been in saltwater most of its life. It's a new boat to me, I've never had it in the water yet.
The question is whether to just do risers and/or manifolds and hope the engine goes for awhile yet OR put a whole new motor in it.
I guess this hinges on the condition of the rod/main bearings which is unknown. Is there an easy way to figure this out?
Is it just not worth the risk of an engine failure, so I should just go new?
Any and all advice is greatly appreciated.

 

[aerwin]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

salt water eats manifolds, that is probley were the water is coming in. manifolds in salt are rated for 2 to 3 years only, fresh water 12 to 15.

 

[Haut Medoc]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

How much $ are you into the boat for?
If the water you are talking is salt water, the prognosis is probably not good........
I'm not an OMC guy, but I know that replacement manifolds are not cheap.....
Obviously you need to determine where the water is coming from.... So you need remove the manifolds & pressure test them......JK

 

[Surfly]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

The boat was a very good deal that becomes a fair deal if I have to put a couple thousand into it.
If I get the manifolds pressure tested and they are indeed leaky, should I worry about the rest of the motor as in bearings etc?

 

[Haut Medoc]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

Well, yeah......Esp. if it is salt water intrusion....
I suppose it depends how bad the oil looked....
How long has it sat in this condition?
The right thing to do would be to get the oil drained, fill with fresh oil, & get it up & running ASAP......
If it has sat awhile in this condition, I would go out on a limb here & say it is probably toast......
Did it have wate rin the oil when you first bought it?
It could have a cracked block or head.....
Pull the mans & look for signs of rust @ the exhaust ports.......Good Luck!.......Haut

 

[Surfly]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

Does the fact that it has excellent compression in all the cylinders rule out a cracked block or head?
I'm not sure how long the salt water had been contaminating the engine, but the oil didn't look too bad.
I'm going to have the cooling system pressure tested as well, and that should help clarify things. Maybe.....
Since I probably have to get new risers and manifolds anyway, I'm thinking of putting them on and seeing what happens. If the motor runs for a season more, fine. If not, oh well. I'll replace the engine using the risers and manifolds I already have.

Thanks for your input.

 

[MortenH]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

Well, I think people have some overstated fear of salt water. I might be wrong, but my LU sat for the whole winter (and probably most of the summer before) with more than 50% salt water in it without a mark on anything inside it. It has been opened, inspected by a pro and resealed.
So I dont think the damage inside the engine is of any big concern. The compression have nothing to do with water intrusion - this only proves that the cylinders, and probably also the heads are fine.
Your plan sounds fine to me, but I am an outboard and aoutmotive guy, not very familiar with marine inboards.

-M-

 

[tashasdaddy]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

is this a vortec engine, if so the overlap of the valves, will pull water back into the engine, if the manifolds and risers are leaking. i learned the hard way. will the engine turn over?

 

[Mystic Dragon]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

Hey, I'm not a mechanic, but if the shutter valve is no good, it could be seeping water into the cylinders.

Just a thought.

 

[KaGee]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

Your mechanic if worth his salt, (pun intended! d ) should be able to nail down the source of the intrusion without a lot of fuss.

Most likey one of the manifolds or risers like already mentioned. The price you pay to play in salt water!

 

[Haut Medoc]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

Surfly, I like your plan....
The block or head can be cracked & you could still have good compression....
The fact that you have good compression is enough for me to say, throw new mans/risers on it & see what happens......
Even if you had to get a new engine, it wouldn't cost a fortune
It's the OMC thing that I would be most concerned about, but if you are in this far...........JK

 

[Surfly]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

Thanks everyone.
I think we have a rough consensus: check out the manifolds/risers and determine if they are the problem. Mechanic says 8 or 9 times out of 10, they are. If so, we get new ones, put 'er back together and get what use we can out of the engine. Could be one hour, one season.....who knows.
Mechanic claims that outdrive has been well serviced and is in good shape, so at least I've got that going for me.
Anyway, I'll be back posting like crazy once the test results are back.
This is a terrific resource.

 

[Surfly]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

PS to tashasdaddy: the motor starts right up and runs just fine.

 

[tashasdaddy]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

you're on the right track.

 

[Don S]

Re: OMC (Oh My Cod) 4.3 Major Dilemma--water in oil

salt water eats manifolds, that is probley were the water is coming in. manifolds in salt are rated for 2 to 3 years only.

I wasn't going to say anything on the above subject, but I really would hate to see people go out and start replacing manifolds and risers after only 2 or 3 years, because they read it here.
That is rediculous. In salt water it's usually around 5 to 8 years they get replaced. At say 4 years, it wouldn't hurt to start pulling the risers off and inspecting the gasket surfaces and the passages for being plugged up.
I wouldn't suggest serious cleaning of the insides, as that eliminates your last line of defence before the things plug up and start leaking. IF your manifolds and risers plug up due to scale and corrosion, then they need replaced and that overheat usually happens just prior to water leaking into the engine. And in salt water, that will take out your engine.
You change impellers every 2 to 3 years, not manifolds and risers.
I also no of no "Rating" ever done on the the life expectancy of manifolds or risers, rather salt or fresh. Somehow I doubt that the 12-15 year thing is worth talking about in fresh water.