Cummins NH250 engine problems

[KHarrower]

While 30 miles into my 70 mile trip to winter snowplowing, my Oshkosh plow truck with NH250 w/turbo started clattering. It was blowing air with some oil out of the vent tube and the temp started to climb. The crankcase has pressure and wants to push oil out of the dipstick tube, and blows out of the oil fill cap on top of one of the valve covers. The water is also going away, but not into the oil. I think I can detect a sweet smell in the exhaust. I suspect a blown head gasket. After talking to a Cummins mechanic, he suspects the same, but says there must be another problem to have caused this. He suspects low compression. Possibly a broken ring, worn rings, or a gouged liner. He wants to look at it, but there is nothing to see unless we pull the heads. I am not sure the truck will be worth putting a new top end on if this is the case. Does anyone concur that the possible blown head gasket is caused by a low compression problem?? Head gaskets would be relatively inexpensive, but rings/liners, heads, looks to me like big $$$.

 

[NIsaacs]

Is the engine missing on one or more cylinders? Pull your valve covers off and check the valve train, clatter is indicative of more than a head gasket. Maybe a broken valve and or a broken piston.



"NICK"

 

[chriscumminsdiesel]

Any excessive smoke? Pull your exhaust manifold and see if any oil or antifreeze are comming out of any ports. At least this will tell you what head to remove. Low compression will not cause a head gasket to blow. Compression in the crankcase could be caused by a hole in the liner,a faulty air compressor,or faulty turbo. I agree,clattering could be a broken piston or valve train component.

 

[KHarrower]

I will try to get back to the truck next week. It seemed to have the same amount of power after whatever happened. I suspect the clattering is from low oil. I doubt I was getting an accurate reading on the dipstick. The truck was smoking, oil or coolant, I don't know which. I suspect coolant. I was as frustrated as DP with my truck, and after thinking about it for a while, I will probably cancel the mechanic, and go down myself, pull valve covers, maybe the exhaust manifold, heads, get an accurate reading on oil and coolant level , and see what else I can find. I didn't have much time to trouble shoot when this happened as it was getting dark. Thanks for the advice.



Kimmer