98 4.3 water in oil after rebuild

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stang32

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I got a motor from someone who rebuilt the motor because there was a squeek in the bottom end, after rebuild, upon 1st start up, he found no oil to top of heads, & pulled the oil filter, found milky oil .
this engine has the 1 piece exhaust manifolds, I think they are called bat wing manifolds,
I pressure tested the engine after removing the exhaust manifolds, blocking off the thermostat housing & water pump ports & it has held pressure for over 24 hrs.
on top of that there are no steam cleaned spark plugs. in fact they are all black.
where did the water come from?
serial # L019142
 
Bondo

Bondo

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Re: 98 4.3 water in oil after rebuild

stang32 said:
I got a motor from someone who rebuilt the motor because there was a squeek in the bottom end, after rebuild, upon 1st start up, he found no oil to top of heads, & pulled the oil filter, found milky oil .
this engine has the 1 piece exhaust manifolds, I think they are called bat wing manifolds,
I pressure tested the engine after removing the exhaust manifolds, blocking off the thermostat housing & water pump ports & it has held pressure for over 24 hrs.
on top of that there are no steam cleaned spark plugs. in fact they are all black.
where did the water come from?
serial # L019142
Click to expand...

Ayuh,.... While those manifolds are JUNK,... water can't get to the oil from there, when the motor is Runnin'...

That leaves a cracked block,...
 
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stang32

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Re: 98 4.3 water in oil after rebuild

Yeah I do not see how the block would bE cracked
I have this thing pressurized & closed off pressure has held since yesterday . I am about ready to put this thing in the boat & run it
It makes no sense that it would hold pressure but allow water to leak into the block
 
Silvertip

Silvertip

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Re: 98 4.3 water in oil after rebuild

Sealant not used on head bolt threads where they pass into the water jacket. Engine would hold pressure but water can get up the bolt holes and back into the crankcase. It's been a long while since I worked on that engine so my comment doesn't apply if the head bolt holes are closed at the bottom. If any are open to the water jacket sealant is required.
 
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dollarten

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Re: 98 4.3 water in oil after rebuild

Sometimes block crack from freezing and some other times just from fatigued I have seen 350 CI Gm race engines that gave way near the lifter bores . A weak area in the area just above the lifter galley can crack .Seeing that marine engines run a harsh life like race engines do , a possibility for cracking in this area could let water into the engine The fore mentioned area was a high failure area in Pontiac race engines due to the stress of the cylinder head bolt clamping , the effects of higher compression and all the valve spring pressure being transferred to the lifter bore area
 
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stang32

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Re: 98 4.3 water in oil after rebuild

but the bottom line is, the engine is still holding steady @ 20 psi for now over 2 days.
this engine since the rebuild has not run more than a few minutes, he shut it down when he found no oil to the heads.

as for the head bolts, if water can work its way up the bolt threads, don't you think air would follow the same path?
 
NHGuy

NHGuy

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Re: 98 4.3 water in oil after rebuild

Turn the motor to get some different valves open and closed, see if it hisses then.
 
Silvertip

Silvertip

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Re: 98 4.3 water in oil after rebuild

stang32 said:
but the bottom line is, the engine is still holding steady @ 20 psi for now over 2 days.
this engine since the rebuild has not run more than a few minutes, he shut it down when he found no oil to the heads.

as for the head bolts, if water can work its way up the bolt threads, don't you think air would follow the same path?
Click to expand...

How things happen on a "cold" engine may be very different on a "warm/hot" engine. But yes -- water would find it's way up the bolts IF the leak existed in both hot and cold states.
 
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