Hi everyone. I recently bought a 1980 kenworth w900a dump truck with a Cummins ntc350 or NH/NT 855. I thought the truck ran fine but i noticed that their was steam coming out of the blow by tube. I started looking into it more and realized that their is a good bit of water in the motor so i drained the cooling system and ran the motor till it got warm in hope to get some of the water out. It continued to steam after doing this a couple times so i tried to Pressurize the coolant system and had no luck. I then took the valve covers off and tried again and noticed that when i would add air to the coolant system more steam would come out of the top of the motor. I also noticed that one of the rocker arms on the front housing had no movement when the motor is running. can anyone help me. Also the air compressor intake is connected to the side of the motor. To what i don't know but i have also been getting a lot of water build up in the air tanks but i don't know if that is normal since this is my first truck with a air break system.
Does the oil level go up when it's parked overnight? May be time to replace the o-rings on the cylinder liners. Pull the pan off and check for water dripping off the bottom edge of the cylinder liners. You need to fix a problem like this right away, antifreeze is real hard on bearing inserts.
The rocker arm not moving makes me think this is going to be much worse than liner o-rings.
With the pan off, to look for the water leak, it's easy enough to check out the cam lobes with a flashlight.
Well good news is it dose not have any antifreeze in it. It is the rocker arm in between the two others on the second cylinder from the front. I looked at it more today and if you push down on the push rod side while the motor is running it lifts and lowers. Their is just no pressure pushing back from the valve or injector (i dont know what it is). After looking at it closely i noticed on the other cylinders this same rocker arm is pushing down a rod with a plunger on the end. The plunger (or piston) is connected to the rod that the rocker arm is pushing on but on the on that is not working correctly i noticed that when the rocker pushes on the rod the rod moves up and down inside of the piston.
Sounds like you have a bad injector on the number 2 cylinder.Here is a thread where I was replacing cummins 855 injectors in the dozer at a jobsite. HeavyEquipmentForums
Would it hurt to try to unstick the injector as long as you don't mess it up so that it can't be rebuilt (if that matters)? I'd try pulling the pin up with a pliers and/or tapping on the pin very lightly with a tiny hammer and punch.
might have a pitted leaking piston liner also. I'd pull the pan and pressurize the system as Mike suggested