4.3 vortec engine ( water in oil )

[Clayclark]

Hey guys new to this forum, but do a lot of reading on here. First off I’m mechanically inclined and do alot of work myself! Ok so I bought a boat fairly cheap for a lil project and finally got it running ( wasn’t getting fire to key switch ), boat didn’t even spin over one time and fired right up and never missed a beat, actually cranks and runs better than my 2017 gmc ! Well I go to check the oil and it was milk, so I drain it and let set overnight with plug out, well today I put fresh oil in it run it on muffs and check oil again and it’s milk, so fast forward , I changed it serveral times with milk as the result! Motor cranks runs flawlessly, I’ve pulled all plugs and all look perfect. Where do I need to start to see where I’m getting water in at without just changing intake, head and manifold gaskets. Thanks and god bless!

 

[stresspoint]

you may have a crack in the engine block or get lucky and its just a head or intake gasket.

i recently went through a saga with the 4.3s where i had 2 cracked blocks , my first experience with the V6 was not pleasant coming from a V8 background .
first block original to the boat had split bore , second one had hairline cracks in the engine block just under the intake manifold that only let water in when engine was under load, PIA that was to get to the bottom of.
i belive yhat the cylinder heads and intake manifolds are bad for rusting at the crossover ports and under the Tstat area.

on the good side , now i have it all sorted with lots of mods to make power and reliability , that little motor is very strong and runs all day on very little fuel.

 

[Scott Danforth]

First, welcome aboard

second, pressure test the cooling water jacket to 15 psi. (involves blocking off the lines to the manifolds and the one from the transom shield). does the block itself hold 15 psi? yes or no

if no, listen for the hissing and find out why.

since you didnt state which one of the 8 generations of 4.3 you have I wont guess. however the 1996 and later motors have had leaking intake manifold gaskets, and if it wasnt winterized correctly, the manifold well under the thermostat housing could be freeze busted

if the block holds pressure, look at the exhaust manifolds and risers. replace as needed.

 

[Lou C]

Yep to all the above, the 96 & up Vortecs had a bad run of intake gaskets that caused problems in both auto & marine applications and they also changed the torque specs to about 1/2 what they were for the pre-Vortec. If these leak not only can you have an intake leak but water will leak from the water transfer ports that connect the cyl heads & the intake manifold right into the cam valley and right into the motor oil but usually not the cylinders. On the older pre-Vortecs these rarely leaked. Personally I think GM made a mistake using plastic framed gaskets & reducing the # of bolts from 12 to 8.
Blown head gaskets are another common cause of water getting in the oil & cyls; as is a lack of winterization & bad exhaust manifolds & elbows.
On the plus side these engines are easy to take apart & rebuild, parts are available and inexpensive, and they are surprisingly economical for their power output. A good choice for 17-19’ boats.

 

[Bondo]

Hey guys new to this forum, but do a lot of reading on here. First off I’m mechanically inclined and do alot of work myself! Ok so I bought a boat fairly cheap for a lil project and finally got it running ( wasn’t getting fire to key switch ), boat didn’t even spin over one time and fired right up and never missed a beat, actually cranks and runs better than my 2017 gmc ! Well I go to check the oil and it was milk, so I drain it and let set overnight with plug out, well today I put fresh oil in it run it on muffs and check oil again and it’s milk, so fast forward , I changed it serveral times with milk as the result! Motor cranks runs flawlessly, I’ve pulled all plugs and all look perfect. Where do I need to start to see where I’m getting water in at without just changing intake, head and manifold gaskets. Thanks and god bless!

Ayuh,.... Welcome Aboard,..... With no known history, the most likely cause is a cracked block,.....

Drain the cooling system, 'n pressurize it as Scott explains, 'n listen, then chase the hissing sound to find the problem,......

Hopefully,...... I'm wrong,......

 

[Clayclark]

Ayuh,.... Welcome Aboard,..... With no known history, the most likely cause is a cracked block,.....

Drain the cooling system, 'n pressurize it as Scott explains, 'n listen, then chase the hissing sound to find the problem,......

Hopefully,...... I'm wrong,......

Okay I’ve read a little about pressurizing the coolant system but still haven’t wrapped my mind around what all needs to be blocked off and how to go about pressurizing it , I have a coolant system pressurizer like that goes in a top of a radiator ! Thanks for these replies any and all help is appreciated!

 

[Scott Danforth]

Hopefully,...... I'm wrong,......

you probably are not.....

 

[QBhoy]

Did you try turning it over with the plugs out ? If that’s been tried and ruled out manifold or riser issues. You’d think it’s got to be inlet manifold, heads or perhaps more likely, frost damage. Was there water in it when you got her ? Or has she been drained ? Was the oil milky before getting her running ?
Was the oil as milky after the oil change, as it was before ? Usually need to do a few changes to get rid of any remaining signs of water. It can gather and stay in the rocker gear for a good while after. Oil cooler, pump and associated network would have water content yet to work it’s way clear too.

 

[Bondo]

Okay I’ve read a little about pressurizing the coolant system but still haven’t wrapped my mind around what all needs to be blocked off and how to go about pressurizing it , I have a coolant system pressurizer like that goes in a top of a radiator ! Thanks for these replies any and all help is appreciated!

Ayuh,...... At the t-stat housin', pinch/block off the in-coming water line, 'n the lines to the exhaust manifolds,.....
Drain the block at both block drains, one each side,.....
Yer rad. tester should terminate to a 1/8" pipe thread, at the rad cap adapter,....Adapt the 1/8" pipe to 1/4" pipe(with a longer hose), which will screw into one of the block drains,.... of course, plug the other block drain,....
Pump it up, 'n it should hold pressure,....

Pull the spark plugs,... pull the oil fill cap,... open the carb to Wot,....
Those will be yer "Listening" holes,.....

 

[Clayclark]

Thanks guys for all the help, much appreciated. Pulled the intake gasket and no leaks found like I was hoping but was prepared for the worst being bought a project boat and not knowing any previous history besides what I was told which you can never believe! Anyway after checking and looking found the block busted pic attached! Okay so now what’s the best way to go, boat has 64.3 hours on it! Gonna do all work myself been mechanic for 10 years and can’t find my way around pretty good ! Thanks again

 

[nola mike]

Next step is a new block. Still don't know what you're working on

 

[stresspoint]

that is what happened to my second engine block, presure testing did not reveal any leaks ars it only became apparent when the motor was under load.
i ran that motor 1/2 an hour on the hose / muffs , it did not even get a drop of condensation in the rocker covers, as soon as i took it over 4k rpm on the water, water in the oil showed.
the actual split was into the water jacket.

looks like you are going to be looking for a new block , make sure you do a crack test before assembling as these 4.3s unlike the V8s have their own inherent problems with cracking by the looks of it.
FWIW , we do not get freezing temps here where i am so the chances of a freeze crack is pretty much 0.

 

[Clayclark]

Next step is a new block. Still don't know what you're working on

2007 chaparral 4.3 vortec mercruiser

 

[Bondo]

Okay so now what’s the best way to go,

Ayuh,..... A Long block crate motor,....

 

[Lou C]

that's the way to go, start with reman block & heads, then get a new intake (unless the old one wasn't cracked) and exhaust (same thing).
As I have said many times the sad fact is that thousands of engines are ruined because Merc and Volvo were too cheap (or the boat companies were I should say) to make closed cooling, at least a half system STANDARD.
You'd never lose an engine due to a quick freeze and you'd have a longer lasting engine if used in brackish or salt water. I have been winterizing mine for 20 years now and when I finally repower it, that is the FIRST thing I am doing to it. GM designed these engines, including the cyl head design, to be cooled by a pressurized cooling system. Open or raw water cooling is just a low cost compromise....the engine runs too cool most of the time and then parts of the cyl heads run too hot, because the cooling water isn't pressurized to eliminate localized boiling.

 

[Scott Danforth]

If the block is freeze busted....assume the heads and manifolds too

 

[Clayclark]

Ayuh,..... A Long block crate motor,....

Anyone have a good source for a cheap long block ?

 

[Superjetjim]

Just curious - could that crack in the jacket within the galley be die ground out and JB Welded if its just a water jacket and hence not under immense pressure, or would that not work?

 

[stresspoint]

Just curious - could that crack in the jacket within the galley be die ground out and JB Welded if its just a water jacket and hence not under immense pressure, or would that not work?

nice thought , but defiantly not , the crack would go through to the head bolt threads..
the crack in the same area on my motor (as mentioned above) did this ,so i would assume the OPs motor block would have suffered the same fate.

 

[Scott Danforth]

Anyone have a good source for a cheap long block ?

Michigan Motorz or GM