Help -- major oil in coolant

ENafziger

ENafziger

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Oct 22, 2008
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I'm looking for some advice here. A couple nights ago when I got home, I noticed that my '91.5 was leaking a lot of black sludge. It looks like the coolant system is filled with oil. There was no loss of power, odd sounds, etc. The truck has ~ 215k miles on it, and I've been running a HE351 turbo for a couple years with maximum boost reaching about 29 psi. It has an easy life serving as my daily commuter and occasional tow rig.

The two thoughts I had, is either the head gasket is compromised, or the oil cooler cracked. Is there anyway to confirm which of these it is? Is there anything else it could be?

What is the best way to go for reliably holding increased boost on these VE motors? I have had thoughts of putting a slightly bigger turbo on it. What boost pressure is a stock head gasket and studs good for? Does an MLS gasket from a 3rd gen fit?

Here's an ugly picture of what I was met with when I pulled the radiator cap:

ry%3D400


Thanks, Eric
 
Oil cooler is most likely to put oil in coolant...
Head gasket/cracked head put coolant in oil
Can pressurize the coolant system while engine off it will backflow and make oil if the crack is big enough.. The hard part is you trying to backflow a ~15# system in to a 60# system at max psi

Let someone else answer the other questions
 
Had that happen. It's a mess to get cleaned up. Was the head gasket..
 
It's a pain but a way to test the oil cooler is plug the ports and pressurize and stick it an water if bubbles come out its no good. Requires the oil cooler to be removed though. I had the same thing happen and it was a headgasket.
 
cumminz90 said:
It's a pain but a way to test the oil cooler is plug the ports and pressurize and stick it an water if bubbles come out its no good. Requires the oil cooler to be removed though. I had the same thing happen and it was a headgasket.
Click to expand...

Thanks. I was hoping there was an easy diagnostic I hadn't thought of to determine what caused it. I think I'll pull the head and go from there. It seems to be more common than I thought for head gaskets to let loose on the 12 valves.

Thanks, Eric
 
5.9 Cummins Fan said:
Last two 1st gens I had this happen to it was the oil cooler.
Click to expand...


Far easier to pull the oil cooler and check it first, then to just pull the head hoping that is your problem.

If the oil cooler is bad, then replace and be on your way. Believe they used the same basic oil cooler from 89-2002 on all 12V motors.
 
thrashingcows said:
Far easier to pull the oil cooler and check it first, then to just pull the head hoping that is your problem.

If the oil cooler is bad, then replace and be on your way. Believe they used the same basic oil cooler from 89-2002 on all 12V motors.
Click to expand...

I second Brian's thoughts. A couple of recent oil analysis reports came back on mine showing a small amount of antifreeze in the oil. The thought of the head gasket came to mind, of course but, I had just put a new one in about 6 years ago. Draining the coolant to replace the oil cooler was far easier and cheaper than replacing the head gasket. Not to mention, it took only a matter of hours to do so. The following oil report came back with confirmation; clean, no antifreeze whatsoever. It was the oil cooler. Given the age and mileage (relatively low for the Cummins) of the cooler, it probably won't hurt to replace it even if it isn't the culprit.
 
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Well, I'm convinced. I'll give the cooler a try first. I presume you have to take it to a radiator shop to get pressure tested?
 
Were it me, I'd just replace it. Much like I did with mine. I didn't bother pressure testing it because I was certain it was the culprit. I had pictures to reference from years ago when I replaced the head gasket. It wasn't obvious to me at the time but I should have replaced it then.
 
I would want confirmation of failure. It takes for-ev-er to clean a cooling system that is still making oil. :p

Make sure the cooler is tested hot. Dunking them in cold water and testing can hide fractures. I like to run coolers in the parts washers to bring to temp and then submerge them.

Sent from my Moto X using Tapatalk
 
I'll second pressure testing while hot. Cracks/holes will open up more then.
 
I drained the oil, and this was stuck to the magnetic plug...anyone recognize it?

ry%3D480


ry%3D480


ry%3D480


I pulled the oil cooler, and things are definitely oily...it's going to take some cleaning.

ry%3D400


Pressure testing isn't quite as easy as hooking up a couple fittings. For those who have been blessed to never have one of these apart before, here's what it looks like:

ry%3D400


ry%3D400


There's really no good way of attaching a pressurized connection. I decided to cut out a plate with the plasma cutter, and weld a couple 1/4" NPT bungs to it that aligned with the oil passages. Fortunately the gasket came off in one piece, and I used it to seal between the plate I made and the oil cooler.

ry%3D400


ry%3D400


...and my cooler is definitely bad. With 15 psi regulated air pressure, the split was obvious. The cooler wasn't corroded in the least. It looks like it was a fatigue crack? At any rate, thanks for the suggestions...I think I'll get a new cooler and put it back together...and save the head studs, valve springs, and turbo upgrade until warmer weather in the spring.

--Eric
 
Purple power degreaser worked good for cleaning up the mess for me. Just be careful because it's corrosive when used full strength.
 
1) replace your thermostat

2) when you put it back together (the engine) , connect some sort of 1/4 turn valve to a high point in the cooling system, like your heater fittings. Take the Tstat out, run the engine until hot with a mixture of dish washing detergent and water. Shut it down and carefully open the valve so you won't be scalded.
Doing this will purge emulsified oil that has come loose and risen to the top of the system. Once that stops venting, drop what's left out of the drain cock. Repeat as necessary.
Eventually flush with straight water until clear or very near.
Also, fill with hot water to speed the process.

Sent from my Moto X using Tapatalk
 
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