Cummins ntc350

[HFservicesNC]

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 tool 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.

 

[HFservicesNC]

Also i forgot to mention that 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.

 

[td25c]

The air compressor is a good place to start looking for an internal coolant leak or if the engine is building excess pressure in the cooling system.Try disconnecting the coolant lines from the compessor and use a short piece of hose to tie them back togather on the engine side so the compessor is isolated from the cooling system.Fill the engine back up and see if it makes any difference when running,dont run the engine more than 5 minutes as now the compessor is not in the coolant loop.As for the rocker arm not moving while the engine is running check for a bad cam lobe.

 

[Delmer]

Water build up in air systems is normal, that's what the drains and alcohol are for. I can't say how much is normal for your truck though.

For the valve/rocker that's not moving, first push the valve down and see if you can pull the pushrod out, it may have bent from the valve sticking.

 

[Cat_man320]

Do what td25 said . If you still have serious issues , you may have a bad head gasket or cracked head . as for the valve not opening , most likly the cam lobe is gone or a bent push rod .

 

[HFservicesNC]

OK i figured out the after cooler was leaking a great deal of water into the motor so i pulled it out and started to try to repair it but due to the previous owner running straight water in it and it freezing it created a lot of holes and cracks in one end. Do i really need a after cooler. I was told the purpose of it is to cool down the intake air. I dont understand how running air over this after cooler that has hot engine coolant running through it is going to cool the air down. That sounds like a air heater to me.

 

[51kw]

That coolant temp after cooler is still cooler than the compressed air coming out of the turbo. It does cool the air and makes a big difference in horsepower.

 

[HFservicesNC]

Where would be the best place to get a cheep replacement.

 

[51kw]

Check with any truck salvage place in your area.