Milky Oil?

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sam.thompson

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Alright still working on this old Mercruiser engine.

1972 Mercruiser 165hp, inline 6, I/O.

Pulled the dipstick to check the oil today, and it looks like Choc Milk. Nice blend of dark and lighter oil.
I got this boat this year from a family member who hadn't been using it, So I recently changed the oil within the last month and the boats only been out twice.

Nothing looks sludgy on the dipstick, the oil was just a different than I'm use to seeing.

IS THIS NORMAL? Or should it still have a shine like new oil or be dark instead of Choc milk looking?
 
spdracr39

spdracr39

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Re: Milky Oil?

not normal. Probably wasn't winterized correctly and something is cracked.
 
Don S

Don S

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Re: Milky Oil?

Is the oil level up a significant amount?
 
Bondo

Bondo

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Re: Milky Oil?

sam.thompson said:
Alright still working on this old Mercruiser engine.

1972 Mercruiser 165hp, inline 6, I/O.

Pulled the dipstick to check the oil today, and it looks like Choc Milk. Nice blend of dark and lighter oil.
I got this boat this year from a family member who hadn't been using it, So I recently changed the oil within the last month and the boats only been out twice.

Nothing looks sludgy on the dipstick, the oil was just a different than I'm use to seeing.

IS THIS NORMAL? Or should it still have a shine like new oil or be dark instead of Choc milk looking?
Click to expand...

Ayuh,... Probably Not, but the more important question is,....

How far Above full is it,..??
 
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sam.thompson

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Re: Milky Oil?

Actually the oil was up the dipstick a fair distance over the actual level line.

Well, where should I start at to looking for the issue?
I have a little smoke coming out of my valve cover vent as well. So I have a little blow my happening. Would this affect the oil at all? Or will I be doing a complete tear down of the valves, head gaskets and such to get down and looking for the issue?
 
Don S

Don S

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Re: Milky Oil?

Well, since it's well over the level, you can bet money the block is cracked.

Pull the side covers, usually you can see the cracks behind the push rods.
 
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sam.thompson

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Re: Milky Oil?

Don S said:
Well, since it's well over the level, you can bet money the block is cracked.

Pull the side covers, usually you can see the cracks behind the push rods.
Click to expand...


So what exactly is happening at this point if the block is cracked? Because it's not obvious from the outside that the block is cracked but I'll open the side covers and take a look. I just want to know for my own knowledge, what is actually going on. Why the cracked block causes the milky water and what I have to start doing to fix the problem.
 
Don S

Don S

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Re: Milky Oil?

sam.thompson said:
So what exactly is happening at this point if the block is cracked? Because it's not obvious from the outside that the block is cracked but I'll open the side covers and take a look. I just want to know for my own knowledge, what is actually going on. Why the cracked block causes the milky water and what I have to start doing to fix the problem.
Click to expand...

If there are cracks behind the push rods, they probably came from water freezing in the engine.
The only fix at that point is a new block or engine.

When you pull the side cover, the wall you are looking at behind the push rods is the wall between the water jacket, and the oil passage (where the push rods live) the water gets in the oil and the pump emulsifies the water and oil and makes it look milky.
 
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skydiveD30571

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Re: Milky Oil?

That chocolate milk colored oil is actually a mix of oil and water. That happens when the engine block develops a crack between an oil passage and cooling jacket, allowing cooling water to get in and mix with the oil.
 
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