Mowing Kubota diesel overheating.

[bearthebruce]

AL radiators do need coolant treatment to stop the growth of Aluminum oxide. I would do as others have suggested, have the radiator cored or replace it.

 

[Ford850]

Do you have the expansion tank filled to the proper level when cold?

 

[blackvette]

I had a ford van with 300 inline 6…..got to where if i turned on the a/c , it would start getting hot…..i did everything…..nothing really helped…..the issue was the radiator’s ability to cool had just diminished to the point it could not keep up. It was clean inside, but it was more complicated than that…
I replaced the radiator for $155 and it ran cool as a cucumber from then on…..$155……..smdh

 

[Ford850]

Maybe there are cheaper replacement options, but the Grasshopper replacement is over $600.

 

[Dan Dargeloh]

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.

This is something you may or may have not checked. My sis-n-law had a Kubota lawn tractor with the 3 cylinder diesel that was doing the exact same thing. I finally discovered that there is a screen in front of the radiator that is not real obvious to the eye. It's purpose is to catch debris before it can get to the radiator core and plug it. It lifts up out of the way. Hers was cover with old grass and stuff which inhibited the flow of air. Cleaned it off and viola, no more heating problem.

 

[CausticUrbanCoast]

Maybe there are cheaper replacement options, but the Grasshopper replacement is over $600.

There are many, it is a generic industrial engine. Measure it and look it up.

 

[fishdrivel]

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

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.

Water cools better but the antifreeze mixfights corrosion. It does get old. If your tractor has 2600 hours on it the additives are likely gone.
As others have suggested, you need to have radiator flushed. It can still flow water or it would overheat in minutes. It will still overheat with partial flow. I would also suggest you change the thermostat. A good radiator shop is not expensive. A new Kubota diesel engine is.
Note: The radiator may leak after flushing since there is likely corrosion. It can be easily fixed while it is out of the machine.

So: Professional radiator flush, new thermostat, new antifreeze and water. Consider new hoses.

 

[4570Man]

I’ll look into 3rd party options for a radiator. I put one on my b7200 for under $200. I don’t think there’s a radiator shop in town. I’d have to go to the next town over 30 miles away. If I can find one fairly affordable for a new one I’d rather do that.

 

[JPinnell]

At that many hours I'd pull the radiator and physically clean the outside. Flush the fins out of debris. They make coil cleaner in a spray can for your Home AC unit which are aluminum. Its just a heavy degreaser but pretty cheap. So Purple Power or Simple Green might do the trick too. My Old Man would mix up some weak muriatic acid in a garden sprayer for coil cleaner. Probably some benefit to a cooling system chemical flush and a new thermostat with that many hrs.

Not sure how exhaust flow is laid out on your ZT. I had a Cub Cadet riding mower that had a crack in the exhaust that bled enough extra heat that it would vapor lock after awhile.

My Kubota B7800 has a creeping heat issue too but only has 800hrs on it. I keep the radiator flushed out with a garden hose a few times a season and carry a big paint brush to keep the cowl screen cleaned off once an hr. I move 5 acres of weedy "yard" and there is a lot of fluff that accumulates. I think airflow will be the biggest issue.

 

[Kubotafan]

You said the rad was clean but is there a screen in front or behind the rad, depending on what way the air is being blown through it by the fan, that could be dirty. I have a Kubota G1800 and when a lot of pollen and blossom coming off trees it will get plugged and cause the engine temp to run higher if not cleaned.