12 Valve water in oil

I did a little searching and found mention of a lot of cases where oil is in the water (blown head gasket) and also where there is a a lot of water in the oil. In this case I have an engine I bought from a friend for a project. I was told that it has a water leak somewhere that is putting water in the oil at a very slow pace. The original owner ran the engine like this for a bit and just changed the oild every so often until he replaced the engine. I figured I would do the same until I could either find the leak or blow the engine up. I hoping for find the leak.

My first though was the head gasket but I have been told that it was changed. I was also thinking about the oil cooler but I believe that the oil pressure should be higher than the water pressure so i would expect to see oil in the water, not the other way around.

Lastnight I pulled the front cover to tab the KDP and I also removedt he P-pump because I wanted to have a look inside the teppet cover. My friend was thinking the leak may be under there. i figured now is the time to have a look. I haven't got the cover off yet.

Anyone else ever see this? Is it possible that the block is cracked internally? Just curious to see if anyone has seen this before and if I am barking up the right tree.

Here is what the engine is in.... Some of you have seen it on here before. It is still not running yet but getting closer...

There are freeze plugs behind the tappet cover. If one of those fell out you would know it. My guess is the head gasket or oil cooler. A small leak like that will drive you crazy.

I would start with the oil cooler. It's easier to do. Not cheap but easier.

As far as I know, coolant can etch the babbit metal the crank bearings are made with. You may want to get an oil analysis done before you sink lots of money into it. Unless you dont mind rebuilding it all.
Its possible theres a crack. sometimes you can tell if its the gasket when the head comes off. Can be the cooler as well but the gasket is much more common.
Depending on the mileage you could just shotgun the head and get a new cummins one loaded for ~900$. Or you could deck yours, magnaflux, clean it up and re-use it.
The last OEM head I had on my truck was original with 220k and very mild mods when I had it replaced due to cracks. The HG had popped and leaked out around #6.
Lots of tricks for tracking down coolant and head gasket leaks. Like checking the coolant for combustion gases, etc.
Never seen a block crack internally. My bets on the HG, but usually its the oil thats forced into the coolant, or the coolant that exits out the side.
If you take the head off, youll want to do the orings and studs while its out.

kawi600 said:

As far as I know, coolant can etch the babbit metal the crank bearings are made with. You may want to get an oil analysis done before you sink lots of money into it. Unless you dont mind rebuilding it all.
Its possible theres a crack. sometimes you can tell if its the gasket when the head comes off. Can be the cooler as well but the gasket is much more common.
Depending on the mileage you could just shotgun the head and get a new cummins one loaded for ~900$. Or you could deck yours, magnaflux, clean it up and re-use it.
The last OEM head I had on my truck was original with 220k and very mild mods when I had it replaced due to cracks. The HG had popped and leaked out around #6.
Lots of tricks for tracking down coolant and head gasket leaks. Like checking the coolant for combustion gases, etc.
Never seen a block crack internally. My bets on the HG, but usually its the oil thats forced into the coolant, or the coolant that exits out the side.
If you take the head off, youll want to do the orings and studs while its out.

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Yeah, i had some concerns about the condition of the bearings. The price was right and if it blows I will rebuild it. It is just going in a toy anyhow....

Once I get the front of the engine back together I am going to pressurize the coolant system and see if I can find the leak.

Can you tell me where you saw the cracks in the head?

On a different forum there was a guy who replaced his head gasket twice because of coolant in the oil. He finally discovered one of the cylinders had a small crack in it. It happens.

your on the right track pressurizing the coolant system before tearing it down.

Diehard Ram said:

I would start with the oil cooler. It's easier to do.

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I agree with this. Quick and easy way to cross it off the list. If it's not the cooler, move on to the next possibility. Obviously, there only so many external components to check before you narrow it down to something internal like the head gasket. Coolant can still make it's way into the oil system as well once the engine is shut down. At that point, cooling system pressure is greater than oil pressure. Only about 15-16psi initially but depressurizing while temperature decreases which could explain the "slow rate" you mentioned.

jimbo486 said:

Coolant can still make it's way into the oil system as well once the engine is shut down. At that point, cooling system pressure is greater than oil pressure. Only about 15-16psi initially but depressurizing while temperature decreases which could explain the "slow rate" you mentioned.

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^^^ This is very true. Slow leaks will drive you nuts!

jimbo486 said:

I agree with this. Quick and easy way to cross it off the list. If it's not the cooler, move on to the next possibility. Obviously, there only so many external components to check before you narrow it down to something internal like the head gasket. Coolant can still make it's way into the oil system as well once the engine is shut down. At that point, cooling system pressure is greater than oil pressure. Only about 15-16psi initially but depressurizing while temperature decreases which could explain the "slow rate" you mentioned.

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Very good point. I didn't really think of that.

I pulled the tappet cover and everything looked fine. No indication of a crack or faulty freeze plug. I have a couple things left to do before I am ready to pressize the system. I may just pull the oil cooler to have a look.

Thanks for the advice guys!