Mowing Kubota diesel overheating.

[4570Man]

In an effort to be slightly more agreeable Not sure what can or can't be un-soldered cored and sealed back up, that is why I carefully said cored/replaced. All my older/bigger stuff is so over cooled it can probably work with 40-50% plugged radiator and still be fine. The little/newer stuff seems to fight so hard to save a buck and a pound, that everything is on razors edge. That is not a provable fact, just my observation.

Best,

ed

There’s no a lot of room to slap a bigger radiator on the zero turn but I agree it’s probably a little too small.

 

[5030]

Ed... One thing about my Kubota M9 cab and that is, there are 3 heat exchangers BEFORE the air gets to the rad. I have the hydraulic oil cooler, the AC condenser and the air-to air heat exchanger and THEN comes the rad, dead last. When I'm working the tractor, I'm pretty sure the air getting to the rad isn't very cool anyway.

In fact, I added a 12 volt automotive style cooling fan with a relay tied into the ac compressor so when the compressor is engaged, the auxiliary cooling fan is running.

least my open station don't have the ac condenser to deal with but nothing beats ac on a hot day in the field.

Still don't have a clue about recoring a plastic tanked rad. Do you?

 

[5030]

I am having the same problem, I'm find it to be under powered for the altitude I am at 5200'. The RPM cannot keep the fan spinning fast enough to keep it cool. It actually slows to a very a very slow walk and eventually overheats. A very well built machine with a huge problem.. I am so disappointed the dealer will not help me even though it has less than 20 hours on it.
Good luck, I hope yours is a belt

Read my post 122.....

 

[4570Man]

Ed... One thing about my Kubota M9 cab and that is, there are 3 heat exchangers BEFORE the air gets to the rad. I have the hydraulic oil cooler, the AC condenser and the air-to air heat exchanger and THEN comes the rad, dead last. When I'm working the tractor, I'm pretty sure the air getting to the rad isn't very cool anyway.

In fact, I added a 12 volt automotive style cooling fan with a relay tied into the ac compressor so when the compressor is engaged, the auxiliary cooling fan is running.

least my open station don't have the ac condenser to deal with but nothing beats ac on a hot day in the field.

Still don't have a clue about recoring a plastic tanked rad. Do you?

My skid steer has the oil cooler and ac condenser separate from the radiator which is a better design IMO. My mini x has them all stacked together. But the ZT that’s having the problem doesn’t have any of that. It’s just got the radiator with a bent driven fan with no fan clutch.

 

[dirttoys]

Ed... One thing about my Kubota M9 cab and that is, there are 3 heat exchangers BEFORE the air gets to the rad. I have the hydraulic oil cooler, the AC condenser and the air-to air heat exchanger and THEN comes the rad, dead last. When I'm working the tractor, I'm pretty sure the air getting to the rad isn't very cool anyway.

In fact, I added a 12 volt automotive style cooling fan with a relay tied into the ac compressor so when the compressor is engaged, the auxiliary cooling fan is running.

least my open station don't have the ac condenser to deal with but nothing beats ac on a hot day in the field.

Still don't have a clue about recoring a plastic tanked rad. Do you?

Yup, my mini has ac hydrolic and oil, I am amazed at how well it does, even if the a/c won't freeze you out.

I honestly really don't know on the plastics, I have welded ATV plactics with varying degrees of success, but, if I was suspicious of a plastic radiator I would probably just order one.

Funny you mention it, but, I am stupid conservative running the ac on hot days, imagine that

Best,


ed

 

[CausticUrbanCoast]

Okay I was lazy and looked up the troubleshooting list: #2 after wong/bad coolant is/are clogged deisel injectors for producing heat above the normal operating temperature of 175-185F.

I had forgotten about the pump and injectors possibly causing heat issues.

 

[5030]

My skid steer has the oil cooler and ac condenser separate from the radiator which is a better design IMO. My mini x has them all stacked together. But the ZT that’s having the problem doesn’t have any of that. It’s just got the radiator with a bent driven fan with no fan clutch.

I have spaces between each and screens between each as well. Never seen a Kubota with a fan clutch candidly. Both mine are solid mount.

 

[number two]

It sure interesting how the new Hot Topics e-mails have boosted replies on the forum!

Good Luck to the OP.
I'm thinking radiator first.

 

[fatjay]

I just overcame this issue with my zd21. It was my hydro filter. Night and day. I did cooling system, oil, filters, the works. Cleaned all the belts, greased spindles, oiled everything. But the filter fixed it in the end.

 

[Victorytree]

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.

You didn’t say what the actual temps are. Didn’t you use your laser thermometer on the head, block, oil pan, and radiator tanks? Always look at the simple solutions first. Maybe the temp gauge or the sender is bad. I’ve seen late model machines de rate and refuse to run repeatedly, when nothing is wrong, but a brain cramp. Bad sensor S, but no actual problem. A million hours of mechanic time is wasted every year in this country on computer and sensor glitches on engines with no underlying mechanical issues. Not to suggest you are dumb or anything, maybe you did confirm that the engine is too hot with your temp gun.

 

[5030]

One item to be aware of (squirreled away in the back of your mind) is that all Kubota engines are well noted for popping head gaskets when overheated. For some reason they do that when they get hot so it's imperative to keep the heat under control at all rimes.

 

[art]

I would have the injectors tested. When one doesn't work right it causes a cylinder to run dry and cause a over heating problem while running extended times.

 

[4570Man]

You didn’t say what the actual temps are. Didn’t you use your laser thermometer on the head, block, oil pan, and radiator tanks? Always look at the simple solutions first. Maybe the temp gauge or the sender is bad. I’ve seen late model machines de rate and refuse to run repeatedly, when nothing is wrong, but a brain cramp. Bad sensor S, but no actual problem. A million hours of mechanic time is wasted every year in this country on computer and sensor glitches on engines with no underlying mechanical issues. Not to suggest you are dumb or anything, maybe you did confirm that the engine is too hot with your temp gun.

About 210 after I got it cooled down some and 230 before that.

 

[Green Sunshine]

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.

 

[Green Sunshine]

I had a similar problem with my Montana diesel tractor and what I finaly discovered was that the cooling fins in the radiator were clogged with built up dust and tiny peaces of grass etc. this was only at the bottom 3-4 inches of the radiator cooling fins so it was hard to see it. Looking at the radiator it appeared clean but uppon very close inspection I spotted the clogging in between the fins, after cleaning that out with some degreaser and water pressure the overheating problem went away. Now I keep a close check on that so it wont happen again.

 

[TBotNik]

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.

Have you flushed the cooling system? Sounds like it needs it! Supposed to flush them every 2-3 yrs!

 

[dodge man]

I would have the injectors tested. When one doesn't work right it causes a cylinder to run dry and cause a over heating problem while running extended times.

I’m pretty sure that’s not his problem, he would notice a cylinder dropping out also. The problem occurs when a injector over fuels a cylinder and causes it to get hot.

 

[ptsg]

Being that the OP already did pretty much everything possible on the cooling system, I'm now start thinking about something else. Something on the mower deck or transmission can be putting an extra load on the engine causing it to overheat or something.

What's the condition of the air filter?

 

[4570Man]

I took the radiator out and cleaned it. It looks pretty clean but on close inspection there was quite a bit of trash in it. I’ve cleaned it, put a new fan belt on, new thermostat in and I’ve got some chemical radiator flush to go in after I put it back together.

 

[4570Man]