Looking for opinions...milky oil

chartersj

Petty Officer 1st Class
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May 14, 2013
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My buddy just picked up a 1981 IMP x250 for next to nothing. The boat originally came with twin small block engines and at some point in its life was converted to a single gm 454/bravo one. When we showed up we found the oil to be milky, but he decides to go ahead with the deal anyways. At first we were thinking head or intake gaskets, but cannot help but think the block could be cracked as well. Previous owner claims he used it once last summer, and only started it on the hose once this spring. We havnt got the engine started yet, we both have been busy and the boat did not come with a battery. I guess we don't really know where to start with it, whether we should try to get the engine started first to see if we can tell where water is getting into the oil or pull the motor and tear it down to inspect the block and change gaskets...
 

tpenfield

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My opinion. Others may vary. I would put new oil in and try to get the engine started. See how quickly you make a milkshake out of the oil.

A cooling system pressure test can identify the source of the water. That can be tough to rig up with an open cooling system, but do-able. Much easier with a closed cooling system.
 

Bondo

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Ayuh,.... I agree with Ted, as usual,...

Cracks are very hard to find in a torn down motor,....

Diagnose 1st, then follow the results of the diagnosis,....
 

Rick Stephens

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Aug 13, 2013
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And don't leave out of your thinking a simple exhaust manifold water leak. The source of your water in an old boat doesn't have to be inside the engine.

Rick
 

chartersj

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May 14, 2013
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Ok thanks for the help, yeah it has open cooling. And yes good point about the exhaust manifolds as well. We believe the block is a 1990-91, 4-bolt, Mark IV, Short deck out of a truck. It has chrome edelbrock valve covers on it.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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the block could be any 1987-1991 Mark IV block (same block in trucks and boats) the chrome valve covers could be simply added bling.
 

savetexomabeaches

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Jul 4, 2013
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I heard adding chrome valve covers adds 20 hp.. at least that's what the guy told me from the auto store that had stuck on breather vents on his honda. I agree with the rest.. You have no idea how that water could have gotten in there. Oil/filter change, run er on muffs.. See what happens.
 

mickyryan

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Apr 18, 2016
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to start don't agitate oil drain it first see how long water comes out it could just be condensation, if you can do a leaktest go for it if not I would say yank it because bottom line you7 are yanking wether good or bad to clean sump of the sludge from water you might get lucky only need to clean engine and reinstall with new oil pump and cleaned system pm me if you want more info as I just did this myself .
if motor spins freely you can also try draining and filling with diesel fuel running diesel fuel through with a drill and a oil pump priming rod to try to clean out best as possible but id go the yanking and cleaning route to be sure the sludge is off the sump.
 
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