Water on top of cylinders and Oil in Exhaust Manifold.

[Leedanger]

Seized up Merc 260 5.7L 350 CID Serial 5424302

I was planning on taking this guy down to the machine shop to have it rebuilt, but I'd like to know for sure what the culprit was before I get too froggy bout' it. So when I pulled the manifolds a nasty oil/coolant mixture came dumpin' out the of the water channel off the risers (both manifolds did the same thing). And when I was pulling off the heads the head bolts also had coolant in them. I haven't pulled the block out of the boat yet to see what's goin' on down below, but my guess is the issue is up higher because the oil is water free.

It gets better...So there is a shower on the back of the boat and the hot water line is hooked up to the block drain on the port side. Is that normal? I've never seen such a thing but to be fair I don't deal with a lot of boats with a hot water need. To me it would just seem that it could rob that port side head or manifold from the water it needs...idk though and that's why I'm askin' you marine magicians.

Thanks for the help.

 

[dubs283]

Re: Water on top of cylinders and Oil in Exhaust Manifold.

coolant?? - you mean green anti-freeze/coolant or sea water??

the reason i ask is, you mention the hot water drawing off the block - this could be one of two things, 1) the hot water just draws off hot sea water in the engine block (raw water cooled) 2) there is a water heater that uses a preheater and this is the line you refer to (closed or raw water cooled)

in either case the exhaust manifolds are water cooled (sea water) so its not uncommon to have water in them when removing if you didn't drain them first

that said if the manifolds/risers are shot, i.e. leaking, there will be water in the cylinders that have the exhaust valve open when the enigne stops running

 

[Bondo]

Re: Water on top of cylinders and Oil in Exhaust Manifold.

Ayuh,.... Was this a Antifreeze winterized motor,..??

Head bolts have the cooling jacket on the other end... that's why ya goop 'em with sealant goin' In...

Why didn't ya Drain the block, Before ya did the Tear-down,..??

The Shower is just plain ole redneck engineerin'....

 

[Leedanger]

Re: Water on top of cylinders and Oil in Exhaust Manifold.

I'm pretty sure I did drain the block first but I wouldn't swear on it now that I think back on it, but yes this was a winterized motor....However I was not the one that winterized it, as a matter of fact I just picked up the boat last week. As per the manifolds, I'd be ok with the coolant in there, that makes sense, it's the massive amount of oil that was mixed with the coolant in the manifolds that makes me uncertain of whats going on. Heads are shot? How else would that much oil get inside the manifolds?

 

[Bondo]

Re: Water on top of cylinders and Oil in Exhaust Manifold.

but yes this was a winterized motor....However I was not the one that winterized it,
How else would that much oil get inside the manifolds?

Ayuh,... Foggin' Oil,..??

 

[Leedanger]

Re: Water on top of cylinders and Oil in Exhaust Manifold.

Ayuh,... Foggin' Oil,..??

Nah....I don't think so....it was a hell of a lot of oil, more so than the coolant I would say. Strange though right...? You would guess with the winterization any oil would get drained out with the water. I guess no sense in tryin to guess what happened,more just the best way to rectify the situation.

Would everyone agree the best plan of attack would be leak testing the manifolds with acetone and rebuilding the heads? Will I be able to see if the heads are cracked once I get all the valves out of there? Lastly, say I come across a running 350 in a 1981 Jimmy, what all would have to be done to make it marine worthy?

 

[MCL]

Re: Water on top of cylinders and Oil in Exhaust Manifold.

Dunno

I fogged my engine by slowly pouring engine oil into the intake while the engine was idling.The engine isnt able to burn that much oil at idle or blow it out the exhaust.So next spring when I removed the risers and saw a pool of oil in the manifolds I freaked out until I remembered the fogging.

 

[UncleWillie]

Re: Water on top of cylinders and Oil in Exhaust Manifold.

... it's the massive amount of oil that was mixed with the coolant in the manifolds...

Oil and coolant do not "Mix".
By oil do you mean it smells?, looks?, or feels? like oil?

If it just looks and feels like oil, It may very well be the Propylene Glycol (PG) used to Winterize the engine.
After a while it gets a bit syrupy.

Wet the end of a finger with the "Oil" and touch it to your tongue.
If it tastes like cough syrup, then it is PG!

I am sure the FDA types are going to freak over that suggestion!

 

[Leedanger]

Re: Water on top of cylinders and Oil in Exhaust Manifold.

Oil and coolant do not "Mix".
By oil do you mean it smells?, looks?, or feels? like oil?

:

Yessur I understand oil and water don't mix and this is why I am confident it is motor oil. I suppose though the way MCL mentions his experience would make sense, I personally just hadn't ever heard of anyone doing it like that. Why would FDA types have issues with that? Your not supposed to drink that stuff? But it's so sweet...how could it be bad for you...? Well, I guess I better stop giving it to my kids then....(joke)...All kidding aside it was motor oil for sure, approx 1/2 a quart and maybe 3/8 quart coolant.

Regardless I've decided to just put a whole new motor in there for now anyways. Do I need to change all the gaskets if I go with a GM crate motor? I found a very lightly used one for what seems to be a good price ($800 with 10k existing miles), however I'm certainly open to suggestions if anyones got one. Is there really any difference between a GM motor put in a truck vs a GM motor with Mercruiser stickers slapped on it? Someone also once told me (true or not its just what they said) that Edelbrock Carbs can't (shouldn't) be used in marine applications. Is that true? If so, why is that?

Thanks for your time guys, I appreciate it.

 

[UncleWillie]

Re: Water on top of cylinders and Oil in Exhaust Manifold.

Yessur I understand oil and water don't mix and this is why I am confident it is motor oil. I suppose though the way MCL mentions his experience would make sense, I personally just hadn't ever heard of anyone doing it like that....All kidding aside it was motor oil for sure, approx 1/2 a quart and maybe 3/8 quart coolant.

I can't imagine getting 1/2 a quart of oil to pool in the exhaust. that is a huge amout of oil!
I fog by mixing up about a pint of 2 stroke oil at 3:1. (Instead of 50:1)
And run that through the motor in the fall until the smoke comes belching out the exhaust.
It leaves a light coating of oil on all the internals.
Yes, it is 2 stroke oil in a four stroke engine. It'll be just fine.
It smokes like all getout at the first start in the spring! Check your plugs after this procedure.

Why would FDA types have issues with that? You're re not supposed to drink that stuff? But it's so sweet...how could it be bad for you...? Well, I guess I better stop giving it to my kids then....(joke)...

I believe you are thinking of Ethylene Glycol (EG) as used in your car.
It is said to be sweet tasting, causing many pets to die from drinking it.

Propylene Glycol (PG) is in many food products.
There is a lot in cough syrup.
It is what gives Nyquil its syrupy consistancy and "Pleasant" favor.
It is considered safe to ingest.
Which is why it is used to winterize the fresh/drinking water holding tanks in RVs and Boats.

 

[Bondo]

Re: Water on top of cylinders and Oil in Exhaust Manifold.

Yessur I understand oil and water don't mix and this is why I am confident it is motor oil. I suppose though the way MCL mentions his experience would make sense, I personally just hadn't ever heard of anyone doing it like that. Why would FDA types have issues with that? Your not supposed to drink that stuff? But it's so sweet...how could it be bad for you...? Well, I guess I better stop giving it to my kids then....(joke)...All kidding aside it was motor oil for sure, approx 1/2 a quart and maybe 3/8 quart coolant.

Regardless I've decided to just put a whole new motor in there for now anyways. Do I need to change all the gaskets if I go with a GM crate motor? I found a very lightly used one for what seems to be a good price ($800 with 10k existing miles), however I'm certainly open to suggestions if anyones got one. Is there really any difference between a GM motor put in a truck vs a GM motor with Mercruiser stickers slapped on it? Someone also once told me (true or not its just what they said) that Edelbrock Carbs can't (shouldn't) be used in marine applications. Is that true? If so, why is that?

Thanks for your time guys, I appreciate it.

Ayuh,....Ya gotta change the core plugs to Brass, if they're steel, not all are...
If the head gaskets were steel shim gaskets, ya maybe ya oughta swap in composites,...
Chances are, it'll come with composites...
Truck Cams run just Fine in a boat...

Then a Crate motor, long block, can be dressed as a Mercuiser....

If ya do that, I'd suggest replacin' or at least testin' the manifolds, 'n risers...

Edlebrock builds a Mighty Fine marine carb,...
It's an exact copy of the Merc/ Weber that Merc still uses.... part for part...
Carter AFB knock-offs,... Great, reasonably simple carbs...