I need Engine Help Cummins 250 M817

travistodd1

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I need some help from someone who knows the Cummins NH250. I suspect best case scenario is a blown head gasket, but that would be lucky at this point.

History; I acquired this truck from a person who bought a property and the truck came with it. The previous property owner advised he had driven it to the property and never could get it started again. I believe this to be true because where and how it was parked suggested it was driven in and parked. When I took possession, it had the electric shut off switch partially disconnected and someone had been messing with the fuel lines, presumably trying to find a fuel delivery problem.

I started tracking problems and ultimately replaced the fuel shut off valve and the fuel pump after a pressure test showed the seals in the pump were leaking badly. I also changed the fluids as a precaution because I am unsure how long the truck has been sitting before I took possession. When I flushed the coolant system it looked bad. It was the color of chocolate milk, I believe there was a great deal of rust contamination for some reason. After flushing for some time, it appeared to be good and I filled with the appropriate coolant.

Today, I was able to get it running after a day of working on it. I had a couple minor leaks I notice on the fuel side of things. I turned the engine off after about a minute of running and walked to the passenger side to discover ALL my engine oil on the ground. It was hard to tell, but I suspect it came out the exhaust. I also cracked the overflow tank and discovered it had built up pressure and now had a dark cast to it (I suspect oil).

How bad does this sound? A bad head gasket wouldn't kill me but be a pain. I just suspect it is more serious, something like a cracked block or sleeve erosion or crack... It sounded great when running, no out of place noises and good throttle response with no missing.

Please help...
 

NDT

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Can you confirm: you say it ran for one minute and in that time 10 gallons of oil ended up on the ground?
 

travistodd1

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Can you confirm: you say it ran for one minute and in that time 10 gallons of oil ended up on the ground?
There is nothing showing on the dipstick now. It had a full 10.5 gallons in it. It was running like faucet unfortunately, I'm not entirely certain where from.
 

NDT

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Well I would enlist an assistant and fire it up briefly and pinpoint where the oil is coming from.
 

travistodd1

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Ok, I may have lucked out. I would be beyond fortunate if what I think happened, actually happened. While I was looking the engine over, I discovered the oil may not have been coming out of the exhaust of the engine, just have been running off the exhaust. Further inspection revealed an open purge valve on the side of the oil cooler housing which was pointed straight at the exhaust directly where the oil was running off. I suspect that was where my massive leak was coming from.

That said, I am still confused as to why there was pressure in the coolant system after running for a very short time. Again, not a great deal of pressure but enough it hissed at me and squirted a little out of the overflow when I released the cap. I don't think there should have been any pressure building that fast.

I am curious, does this seem like symptoms of a leaking seal on the cooler housing?

Sorry for all the questions, this is my first military vehicle and a lot different than the old Harley's and hot rods I am used to working on.
 

WillWagner

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Head gaskets won't put oil in the coolant. At idle and cold, the oil pressure is WAY higher than coolant/block pressure. Is the overflow tank above the exhaust? My best bet, without being there is a failed oil cooler bundle or just the o-rings considering how bad the cooling system looked before.
 

travistodd1

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Head gaskets won't put oil in the coolant. At idle and cold, the oil pressure is WAY higher than coolant/block pressure. Is the overflow tank above the exhaust? My best bet, without being there is a failed oil cooler bundle or just the o-rings considering how bad the cooling system looked before.
Yes, the tank is right over the exhaust. I may order a gasket set and tear into the cooler to try and what's going on. It sure pumped out all the oil fast. I guess that means the old pump is good....
 

NDT

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Well that is encouraging. On the cooling system, fill the reservoir and leave the cap off while running and look for bubbles. There could have been some trapped air on your first try that was escaping.
 

travistodd1

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Camp Verde, Arizona
Head gaskets won't put oil in the coolant. At idle and cold, the oil pressure is WAY higher than coolant/block pressure. Is the overflow tank above the exhaust? My best bet, without being there is a failed oil cooler bundle or just the o-rings considering how bad the cooling system looked before.
Yes, the tank is right over the exhaust. I may order a gasket set and tear into the cooler to try and what's going on. It sure pumped out all the oil fast. I guess that means the old pump is good....
Well that is encouraging. On the cooling system, fill the reservoir and leave the cap off while running and look for bubbles. There could have been some trapped air on your first try that was escaping.
I will give that a shot. I'm crashed today giving my body a little recovery time from yesterday's antics. I'll probably go get some oil later and fill it back up and see what happens.
 
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