Over heating digger (Isuzu engine)

[T C]

We have an old sumitomo SH60 (jcb JZ70). It is showing high water temperature after 10 minutes from start up. If I take the thermostat out it runs cool. Tried a new stat and it still overheats. There is not pressure in the radiator. I am running a flush in it to see if that helps. Any clues as to what might be going on.

 

[Adeptandy]

Pressure wash the radiator has worked for me in the past, even when it looked clean.

 

[T C]

Pressure wash the radiator has worked for me in the past, even when it looked clean.

But it keeps cool with no thermostat.

 

[Wisconsonian]

Are you getting any circulation of the coolant? like is the water pump impeller broken off? Two minutes with a non contact thermometer will tell you what the temps are going to the radiator, coming back and the block and head temps, that will tell a lot.

The fact that it keeps cool with no thermostat is very odd, and good to know, but use that info to fix it, don't run it like that. Have you tested the thermostats in hot water to see if they open at the correct temp?

 

[startinghandle]

Have you put new thermostat in correctly and not blocking bypass?

 

[Timbo]

Impeller fallen off or slipping on water pump shaft ???

 

[T C]

Are you getting any circulation of the coolant? like is the water pump impeller broken off? Two minutes with a non contact thermometer will tell you what the temps are going to the radiator, coming back and the block and head temps, that will tell a lot.

The fact that it keeps cool with no thermostat is very odd, and good to know, but use that info to fix it, don't run it like that. Have you tested the thermostats in hot water to see if they open at the correct temp?

Got a thermometer coming. Suspicious of the water pump as there does not seem to be much flow of water. Did wonder if the pump is failing and cannot push enough water through the open thermostat.