Mowing Kubota diesel overheating.

[4570Man]

I’ve got a grasshopper ZT with a Kubota diesel in it. It happens fairly slowly but the temp keeps creeping up. The radiator is clean. The air filter is clean, the fan belt is tight, the fan shroud is in place all but a little bit at the bottom which I don’t think has ever been there. There’s no fan clutch, it’s direct mounted. I’ve taken the thermostat out and ran without it and there’s no change. I put the thermostat in a pot of water and heated it on the stove and the pot was very near boiling before it opened. I honestly thought it would fix the problem taking that out but it didn’t. I might repeat that that test with a thermometer since it was supposed to open at 160 degrees. I’ve taken the side panels and hood off to see if better ventilation would help and it does but not a notable amount. And it blows more heat down my back that way. The radiator is as hot as the block when checked with an infrared thermometer. So it seems to me the radiator is taking heat but not loosing it. I’m pretty much at a loss on this one.

 

[ptsg]

Maybe it's time to flush the entire cooling circuit. The radiator maybe clogged inside or something.

 

[Midniteoyl]

You did make sure you could see light through the radiator, top to bottom, correct? Barring that, I would agree that a proper flush is in order next.

 

[4570Man]

You did make sure you could see light through the radiator, top to bottom, correct? Barring that, I would agree that a proper flush is in order next.

Water easily flows through it from a water hose.

 

[Williy]

Do you have the right mix? water alone will
not work and anti-freeze needs water to work

willt

 

[4570Man]

I’ve replenished what was lost removing the thermostat with straight water but it was a good mix before that.

 

[RickB]

How many hours on the machine? If over 500, pull the radiator, remove the shroud and thoroughly clean the core including the corners. Install a new stat.

 

[5030]

Do you have the right mix? water alone will
not work and anti-freeze needs water to work

willt

Actually, distilled water has the best heat transfer ratio of anything. AF is only needed when the ambient drops below 32 degrees (F).

 

[4570Man]

How many hours on the machine? If over 500, pull the radiator, remove the shroud and thoroughly clean the core including the corners. Install a new stat.

2600.

 

[Unclewillie]

I’ve got a grasshopper ZT with a Kubota diesel in it. It happens fairly slowly but the temp keeps creeping up. The radiator is clean. The air filter is clean, the fan belt is tight, the fan shroud is in place all but a little bit at the bottom which I don’t think has ever been there. There’s no fan clutch, it’s direct mounted. I’ve taken the thermostat out and ran without it and there’s no change. I put the thermostat in a pot of water and heated it on the stove and the pot was very near boiling before it opened. I honestly thought it would fix the problem taking that out but it didn’t. I might repeat that that test with a thermometer since it was supposed to open at 160 degrees. I’ve taken the side panels and hood off to see if better ventilation would help and it does but not a notable amount. And it blows more heat down my back that way. The radiator is as hot as the block when checked with an infrared thermometer. So it seems to me the radiator is taking heat but not loosing it. I’m pretty much at a loss on this one.

had a friend purchase on of those that's cooled by a belt he got it cheap cause it was overheating and like you trying / tried everything except replace the belt and in this case that's all it was. The sides of the belt wore slick and didn't grab as designed.