A little coolant in my oil

[Johnstra]

My last two oil samples showed a bit more potassium than is normal and a slight amount of water was detected too. Other than oil cooler and head gasket what other interfaces might leak small amounts of coolant into the oil? I'm thinking I'll start by replacing the oil cooler as that's a lot easier and cheaper than checking the head gasket. Anything else I should be thinking about?

-john

 

[p-Bar]

Heard of a few oil coolers going. When you remove it I would have it pressure tested to see if that is it. Probably a radiator shop could do that.

 

[rbattelle]

Beware that Cummins specifically states that the only way for the oil cooler to leak is if the element itself actually breaks - there are no fittings or anything in there to leak. You have to physically puncture the cooler somewhere.

Before changing the oil cooler I'd check to see whether there's oil in the coolant. Oil pressure is higher than coolant pressure, so when the engine is running oil should be running into the coolant.

Ryan

 

[Johnstra]

Thanks Ryan. I do remember reading about the oil pressure being higher than the coolant pressure in the oil cooler. That's good info because I don't think there's any oil in my coolant. My coolant level has not change in the 25k miles I've owned the truck either.



My oil sample @ 5000 miles showed potassium at 9ppm. The sample before that was @ 14,000 miles and potassium was 18ppm. Terry Dyson said that looks like a very minor coolant leak.



Not sure how I should go after this.



-john

 

[betterthanstock]

There are some coolant stop leak solutions that they say you can leave in even in a new engine. I don't know about compatibility with HOAT coolant. If anything, the stop leak solutions may cause the water pump seal to go sooner.



Or you can drain and fill with just water and stop leak, then a week or two later, drain and refill, and you may need to replace pump soon thereafter.