Engine/Transmission (1994 - 1998) Oil in the Coolant?

[Piston Slapper]

We'll we suspected a blown head gasket due to numerous stretched head bolts that would not torque to 125 before pulling head. We then attempted to pull the head to see what was going on when two of the head bolts broke. We thought we had found our problem and new the gasket had been compromised due to head rising/stretched bolts. To our suprise the gasket had not blown!



After a little head scratching we stumbled across our "real" issue. We had oil in the coolant! We hadn't even noticed it! Overflow coolant tank is black! Only a gallon of oil left in the block. Barely reads on the stick. Suspect a gallon is in the coolant system! Now we suspect the oil cooler on the side of the block. We pulled it out and too our suprised there is no oil in the coolant area there? We are really head scratching now... Our thoughts: Coolant in oil=Head Gasket, Oil in Coolant=Oil Cooler.



We got the Oil Cooler off the truck and pressurized it and cannot get it to leak. We suds here up with soapy water and can't get a bubble anywhere. Althought we can't visually find any faults in this location we still think that this is where our problem is. Numerous conversations with other diesel mechanics advised this is the case 90% of the time. We are now trying to determine what or why else could there be oil in the coolant? Cracked block? We hope not. Still in persuit... .



Any suggestions??

 

[krs]

I'd look real close at the areas of the block/head where a pressurized oil passage goes through. Your oil pressure is higher than your cooling system pressure and a head gasket doesn't have to "blow" to leak badly enough for pressure oil to get to a coolant passage, and you're describing a pretty likely warping scenario. It doesn't take much black oil to make a mess out in the coolant recovery bottle.

 

[gcorron]

I've never heard of this problem with the Cummins. Does not mean it is not there.



On Cat's we had several instances where we had oil in the coolant, took the coolers off and attempted to pressurize like you did with the same results.



I lucked into a guy who used to work in Cat hq writing their training programs, and teaching as well. He said replace the cooler, you cannot duplicate 40psi oil pressure, and 15 psi coolant pressure to perform test accurately.



I did, leak went away. sounds like same problems, I'd certainly consider replacing the cooler, but also sounds like you have problems with the head make sure you've taken care of those first.

 

[Piston Slapper]

We think it is the coolers also. We have purchased one for $400 tax and all. This is jobber price! We was floored at the cost. Replacing head gasket, all head and rocker arm assembly bolts, and cooler. Gonna end up having $1000 in before we are done with head work, hoses, belts, etc... Very expensive cooler and Head Gasket!

 

[gcorron]

Roger that Slapper,

The Cats I'm talking about were 3512's and 3516's, the cooler was between 5-6' long. One man can remove, but he better be healthy



As I recall (the last time I worked on these was about 5 years ago) they were $2,300 wholesale . It was still a leap of faith to replace that first one just on that guys best/guess, but he was definitely right in that case.



Good luck, let us know, did you say you were having the head and block magna-fluxed?

 

[JohnE]

cleaning the oil

I asked the local cummins shop if they use Fleetguard products to flush & clean the cooling system. They said NO. They use low suds floor cleaner to wash the cooling passages.

Washing the block is very important for restoring cooling system efficiency.

 

[NScott]

I have just gone through the same thing/problem with a early 98 12V. Same thing... oil in the radiator-overflow tank. I didn't take the head off though. I first pressureized the cooling system to around 15psi and left it there over a weekend. On monday it still had about 14psi!!! I figured the head gasket was still good at that point... to make a long story short I replaced the oil cooler and the problem is solved, however it could have been only one of the cooler related gaskets and not the cooler itself. . no way to tell, I just replaced cooler and gaskets.

 

[JCarrell]

Originally posted by gcorron

Roger that Slapper,

The Cats I'm talking about were 3512's and 3516's, the cooler was between 5-6' long. One man can remove, but he better be healthy

I machine the cranks for theese

 

[gcorron]

I gotta say you do NICE work. I kept waiting for a broken something off these things for show and tell, never did have many parts. We had 3 3516's and 6- 3512's on gensets, plus a few smaller Cats spread around.



A commercial seller of power has 8 set up on top of a local nearby landfill running off Methane, he has to replace all the heads every year, but that's about the extent of his items also.



Considering they run 24/7/365, that ain't bad - methane DO hate valves.

 

[Piston Slapper]

Thanks for all the replys... It wasn't us that pulled the head, our pump boys had the truck and was tuning on it when the Cooler(we suspect) blowed. They thought it was the head gasket and went ahead and pulled the head. It was a blessing in disguise due to two stretched bolts we found that broke upon removal. So we killed two birds anyway. We still suspect we are going to have to O-Ring/Fire Ring later anyhow, but live and learn. This super duper hotrod diesel stuff is a learning curve for us. We are definetely getting alittle big for our britches, but it sure is fun!!