Possible Sources of Coolant in Oil?

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tohnloke

tohnloke

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Hey all,

It's been kind of a long road but I'll try to hit the important parts. 383 rebuilt about 7 years ago, but probably has less than 1,000 miles on it.

Spring 2022, I went to change the oil and get things going for the season and it was milky and very green (picture attached).

Car sat for 2 years basically until this week. I did a radiator pressure test, and the car held 14 psi in the cooling system overnight. Then I did a compression test, and cylinders all have good compression (150 psi +/- 5).

I ordered a leakdown tester and will be doing that next. But are there other places besides the head gasket I should be looking into for possible sources of coolant contamination?

The only other clue I have is that the engine has always had excessive crankcase pressure.

Thanks in advance,
Tony

IMG_20220410_130029321.jpg
 
I stuck a boroscope down the cylinders and everything seemed to look okay. Carbon buildup - seems like the car has been running rich based on that and the plugs but I think that's unrelated.
 
On a BBM, it’s pretty much head gaskets or a crack/hole in a casting somewhere.

I assume the coolant level is dropping?
 
PRH said:
On a BBM, it’s pretty much head gaskets or a crack/hole in a casting somewhere.

I assume the coolant level is dropping?
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Not that I've noticed although it's basically been parked for 2 years so it's hard to tell for sure. It was just weird what when I pressurized the coolant system it held pressure - I would've expected that to push coolant somewhere.
 
tohnloke said:
Is the intake manifold still suspect on a big block? I wasn't sure if that was only on the small block cars.

Thanks for the heads up on the timing chain.
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If I recall, big blocks head bolts go into the coolant, so it might just be seeping up around the head bolts.
 
If the oil is green, the coolant level is certainly dropping.
 
I'd be checking the cylinder walls for a crack.
 
Had a friend with a 512 with the same issue. Had a small crack in the block.
 
fishmens67 said:
I'd be checking the cylinder walls for a crack.
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I didn't see one on my initial look, but it's definitely possible.

I think the strangest thing to me with all of this is that the cooling system pressure test held. I would've expected to see some pressure loss with the coolant pushing somewhere as green as that oil was.
 
Maybe air pressure test? Drain the cooling system and add 12-13 psi. Listen for the leak.
 
What Dave said. It takes a pretty good leak to see the gauge drop on a pressure tester if the leak is below coolant level. Before you drain it put pressure on it and use your bore scope one more time. Take the oil pan drain plug out and look from the bottom up. If you can't find it try it with the coolant drained and listen carefully while watching the gauge to see if it drops.
 
I know this sounds crazy,,,,,but what kind of oil are you using .
Years ago,,,,I decided to use some ultra cheap stuff for my daily driver truck,,,,you know,,,,what could it hurt to try .

The oil turned red after a few heat cycles,,,,,looked like pure rust mixed with blood,,,,scared me to death almost .
Drained it,,,,went back to normal stuff,,,,no more weird colors .

The reason I say this is because you aren’t losing water,,,,,and I’ve never seen oil and antifreeze mix like yours .

Tommy
 
Desoto291hemi said:
I know this sounds crazy,,,,,but what kind of oil are you using .
Years ago,,,,I decided to use some ultra cheap stuff for my daily driver truck,,,,you know,,,,what could it hurt to try .

The oil turned red after a few heat cycles,,,,,looked like pure rust mixed with blood,,,,scared me to death almost .
Drained it,,,,went back to normal stuff,,,,no more weird colors .

The reason I say this is because you aren’t losing water,,,,,and I’ve never seen oil and antifreeze mix like yours .

Tommy
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I've actually wondered about that. I believe it was Castrol but it was a few years ago now
 
tohnloke said:
I've actually wondered about that. I believe it was Castrol but it was a few years ago now
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Quick way to tell. Put some on your finger. touch your finger to your tongue. If it's sweet it's antifreeze.
 
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