Tractor Repair: Cooling problems on a Case IH 685 deiseltractor, water pump impeller, radiator shop

Question
This tractor overheats within 30 min of use.  The temperature climbs to 1/4" of
red line and then into the red sometime later.   I had the radiator cleaned and
changed the thermostat, and added new coolant.  Do you have any other
suggestions?

Answer

  Hello,

   When you say you cleaned the radiator, do you mean you sent it in to a radiator shop and had it cleaned on the inside, or do you mean cleaning the fins on the outside?  If you had the inside cleaned, good.  If not, do so.  Even if the fins on the outside look clean, shine a flashlight through it and see if you can see light through it.  They sometimes plug on the inner rows of tubes.  If everything is good there, make sure the temp gauge is telling you the truth.  I use an infrared temp gun to verify engine temp, but a thermometer in the radiator will also work, but will read slightly cooler than engine temp.  If the gauge is correct, check the injection timing.  Incorrect timing can cause overheating. If the horsepower has been turned up, it will never run cool enough under load.  You probably already checked the fan belt, but I'll mention it anyway.  Make sure it's in good condition and tight.  A glazed belt can slip even if it's tight.  Look in the radiator with it running and see if there are bubbles moving all the time.  If so, the head gasket is leaking hot exhaust gases into the cooling system.  If everything else is OK, check the water pump impeller.

                              Good luck,

                                    Arnie