I'm not a mechanic, and I am a new diesel owner. I've been having problems with the engine running hot. The top of my radiator is hot but the bottom is freezing cold. When I take the radiator cap off and hit the accelerator the coolant doesn't move. I suspect radiator clogging, or a thermostat problem. It was running fine one day, then the next day running hot. Has anyone ever had this problem?

 

sounds like a thermostat and air in the system

 

Sounds like the thermostat. I had the same problem on my dodge and this is what I did. I started and changed the thermostat. That didnt fix it so I did the water pump since it was the next cheapest thing and it fixed my problem. If neither of those work for you I would see if the hoses are vacuuming shut. Sometimes they can collapse in on themselves if they are going bad. If they are good then the radiator is your next bet. The nice thing is that there is only so much in the cooling system you have to look at. If it persists, it may be something more serious.

 

like stated above, replace thermostat. only use motorcraft or Navistar thermostats. the aftermarket ones do not have the proper bypass in them an can cause overheating.

also when u have ur thermostat housing off, make sure the little steel "ball bearing" is still in the bypass port in the housing. u will see it right away if not u need to replace the housing.

also check the top and bottom hoses. i know the bottom one should have a coiled spring inside it to stop from collapsing. i belive the top has one also but not sure.

if u need to replace waterpump, beware of the top two bolts. if they are two long for the new waterpump they will rub on the injection pump gear and do very bad damage. there should be a warning in the box of the new pump.

 

sounds like an air lock take off the top heater hose and fill thru rad till fluid runs out ill bet heater blows cold also cheaper than all the other