Kubota, L295 DT with D1301D engine 1981-1982

Russell Dean · Dec 18, 2014

Engine is overheating. Replaced head (new) 100 hrs ago, new water pump last year, new thermostat, temp sender, radiator has been boiled out and rodded and is like new. Replaced soft plug on block behind clutch. Other incidentals include new gaskets where needed. New starter, alternator, injection pump, battery. Engine ran like a champ until this last August. I watch the temp gauge like a hawk. It has never overheated to the danger zone. If it gets close I shut it down carefully. Removed the head thinking it may have cracked. Sent in to have Magna-fluxed it came back excellent. Reassembled to specs and it still runs hot, almost to the H mark on the gauge. What am I missing here? If anyone has suggestions I would certainly appreciate your input. Thank you.

dangier_VA · Dec 18, 2014

Is your temp sender electric or thermal? If electric, check to see if the gauge itself responds to spec. If thermal, put the sender in boiling water (212 deg), and you should be somewhere close.

kco · Dec 18, 2014

With all the work done I imagine you ran a cooling system flush additive when changing the antifreeze to clean the engine water passage ways?

If it is not boiling over it is likely OK to run as is.

I am surprised you have a temperature gauge. I had a 1981 L275 DT which did not have a gauge. It had an overflow pipe with a whistle to alert to an actual boil over. I did that a couple of times when the fan belt came off. I'd put it back on and it would invert itself and come off again. But it looked fine. The dealer told me it was caused by some of the belt's internal cords being broken. I replaced it and it was fine. It never boiled over again but I had no idea how hot it was running because it didn't have a gauge.

Russell Dean · Dec 19, 2014

Electric. Good thought on the gauge. I assumed (dangerous) the gauge would be good after replacing the sender. I'll test it out. Thankyou for your help.

Russell Dean · Dec 19, 2014

Yes mine is gauged. I did a quick flush but used Bars Leak after change out. I had better try re-flushing the system as I notice some residue when I had the radiator reworked. Thanks for your help.

Jerry/MT · Dec 19, 2014

Russell Dean said:
Engine is overheating. Replaced head (new) 100 hrs ago, new water pump last year, new thermostat, temp sender, radiator has been boiled out and rodded and is like new. Replaced soft plug on block behind clutch. Other incidentals include new gaskets where needed. New starter, alternator, injection pump, battery. Engine ran like a champ until this last August. I watch the temp gauge like a hawk. It has never overheated to the danger zone. If it gets close I shut it down carefully. Removed the head thinking it may have cracked. Sent in to have Magna-fluxed it came back excellent. Reassembled to specs and it still runs hot, almost to the H mark on the gauge. What am I missing here? If anyone has suggestions I would certainly appreciate your input. Thank you.

Check the gauge to make sure that it's giving you the correct readings. The sending units can go bad. You can use a cooking thermometer or an infrared thermometer on the upper radiator tank to get a good idea if it's really overheating.

If it really is, then make sure that:
the thermostat is working properly
the water pump drive belt is tight
the lower hose does not collapse when you rev the engine
the pressure cap is the correct pressure and is working properly
the air side of the radiator is clear
the air filter is clean (a restricted air filter will lower the airflow and so the fuel to air ratio increases and that means higher peak combustion temperatures)

Russell Dean · Dec 19, 2014

All of the suggestions with exception of air filter have been done. Thanks for the tip, I am going to check the air filter which I cleaned prior to haying. It has been dry and dusty so you may have hit upon something I hadn't considered. Happy Holidays to you and your family.