Kubota 1140 CPX Overheating

   / Kubota 1140 CPX Overheating #1  

buckkoo

New member
Joined
Apr 20, 2015
Messages
3
Location
Henderson, NC
Tractor
Kubota 1140 CPX
I recently purchased a 1140 CPX from a fellow in western NC that had brought several back from Texas for resell.

The RTV has 645 hours and apparently had a history of overheating.

He said his mechanic removed the head, replaced the head gasket and pressure tested - everythink checked out.

He said they determined the thermostat housing gasket was the source of leak and replaced - solving the issue.

I picked up the RTV, got it home and after a longer test ride, the temp needle pegged right.

I removed the radiator cover and saw the fan, not moving. I replaced the fan with a new one for a 96 Honda Accord, which fits perfect and blows air through the radiator well.

RTV still over heats. I notice the fan always runs and after reading postings here, I replace the sensor at thermostat, now fans cycles on and off, but of course still overheats.

So, maybe the thermostat is stuck? Removed thermostat housing and thermostat was completely missing, so i installed a new one. Of course it still overheats.

So maybe the radiator is clogged? Removed the radiator and had it cleaned. It had a small leak and was pretty clooged according to the shop. With the repaired radiator, it still overheats .

So what's left? All the hoses look good from what I can tell. Water pump? When I remove the radiator cap from the radiator, the water is hot, however i don't see any water flow.

Should I? Thinking i should replace the water pump, just because there's not much left.

Any ideas?
 
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   / Kubota 1140 CPX Overheating #2  
Sorry to hear about this...Since it seem that all of the obvious stuff has been covered, I wonder if someone dumped an excessive amount of mechanic in a can in the cooling system in an attempt to seal up a leak...Only a guess...Maybe a thorough cooling system flush is in order since you stated that the rad was somewhat clogged.

Since the fan is cycling, I would guess that there is some flow to trigger the sending unit. Check the hoses and see if one is markedly cooler than the other, that can show a flow issue sometimes too...don't get burned though.

All guesses on my part.
 
   / Kubota 1140 CPX Overheating
  • Thread Starter
#3  
Flushing might help, however I would think that most of the sealer and grunge would have been caught by the radiator, which was just flushed.

I was hoping someone comment on the water flow. When I remove the radiator cap, with the thermostat open, the water at the top of the radiator is as still as a glass of water sitting on a table. Not a wave, ripple or any sign of movement.

Is that normal and the water circulates without any obvious flow?
 
   / Kubota 1140 CPX Overheating #4  
Well, interesting experiment. About 55 degrees this morning.
I went out and removed both radiator caps, reserve fluid bottle is about half full.
Fluid level at radiator is absolutely at max level of removed cap neck...maybe a few drops fell away.
Fluid level at cap along upper hose route in front of thermostat is below cap neck, maybe half an inch.
I replaced radiator cap on top of radiator, feeling that I only needed to observe one opening and not wishing to lose too much fluid.
NOTE... although both caps LOOK identical, they are NOT interchangeable...took me a while to figure this out...different colors on the caps.
I felt both upper and lower radiator hoses...same temp from overnight sitting...cool to touch..
Started RTV, observed fluid in one remaining opening with flashlight so I could see down into opening.
Initially, no fluid movement, then obviously fluid expansion due to fluid expansion began and level slowly rose until it began dribbeling over neck.
No obvious fluid movement.
Felt both upper and lower hoses...initially, no temp change perceived
Then slowly upper hose warmed up, dribbles continued, vapor began coming off into the cool morning, lower hose still cool.
No fluid movement except the vibration from running engine and upward fluid expansion.
After maybe 5 untimed minutes I noticed that much more noticeable vapor was happening, lower hose is now at approximately same temp as upper. I infer that the thermostat has opened up.
I have been watching temp gauge and it has been pegged low...but now it is just barely above the low pegged point.
Still, I observe no obvious fluid movement thru the open radiator opening although it continues to dribble over and sometimes I think that maybe I see a slight swirl...but it is really subtle if at all.
Killed engine and replaced cap.

Conclusion: A properly operating coolant system will heat the upper radiator hose first, then the lower hose after the thermostat opens up. A small amount of fluid is lost during observation but since the coolant is slightly green but clear, fluid motion will not be extremely obvious since there are no bubbles or particles in it to facilitate observing the flow which is obviously occurring within both upper and lower radiator hoses, thru the radiator.

My RTV has the original factory coolant. I HAVE had the radiator get clogged with dust with resultant temperature increase (not to red line). Problem solved immediately by running water thru radiator, externally from water hose, washing the dust off radiator fins. My radiator fan DID fail, an attachment point gave way and the blades were caught when fan sagged into radiator. I replaced with a fan from a Toyota, almost perfect fit and it has held for about 2 years. I have over 600 hrs on it, purchased new.

I am kinda out of ideas...you seem to have done everything I would have done. I have not been into the coolant system nearly as far as you already have been. Maybe you can observe coolant flow if you were to insert something into the radiator flow stream, like a string on a stick, to observe direction, onset and flow rate.

Do you see bubbles in the coolant...or oil...either would not be a good thing...
 
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   / Kubota 1140 CPX Overheating #5  
Here is a picture of an RTV1100 2009 Coolant System;

You mentioned it had not thermostat and was still overheating. You cleaned the rad no difference. New fan no difference.

Suggestions;

Remove hoses from rad and flush hoses and engine (with thermostat out) by forcing water into lower hose and watch for flow coming out of upper hose ( should match input into bottom hose).

Remove and check water pump for damage.

Other than a hose inspection to check the inside for deteration or blockage (doubtful) the hose should be okay as this is too new a machine for that issue.

Most likely, warped head.

Leaking head gaskets often get fixed with new gaskets but the problem of overheating reoccurs because head was never checked for warping.

Good luck.

RTV1100 Coolant System.jpg
 
   / Kubota 1140 CPX Overheating #6  
I have been following this thread and just remembered my problems with a new Ranger that the dealer installed a heater on before I picked it up. It would peg the meter ever time I tried to use the Ranger. I ask the folks on a Ranger Forum and a fellow that mfg custom parts for Ranger's told me I had air in my cooling system. These UTV's have a very small amount of cooling in their system. He told me to jack the front of the machine up with a floor jack and remove the radiator cap and squeeze the cooling hose near the engine, use gloves if it is hot. Ask me how I know. After squeezing several times I heard air bubbles coming from radiator cap area. That was 8 year ago. Seems you had check everything that could affect the system. Good luck.
 
   / Kubota 1140 CPX Overheating #7  
I have an 1140 rtv and it definitely has a problem with overheating. I think this was a just a poor design on Kubota's part. The air filter and the radiator are located where the front tires kick up dust and it goes directly in there. They have changed this on the newer models and moved both to the front (where they should be). I have to use my air compressor and routinely blow out the radiator from behind the fan. You would be shocked how much dirt comes out of there every time. And blow out the air filter. Just a bad design that I don't see a fix for on my unit. I guess I'll just have to deal with this until it gives out on me and then I'll buy a new one.
 
   / Kubota 1140 CPX Overheating #8  
Did you check and make sure the temp gauge is reading correct? How about the fan belt is it tight and not slipping? Just a couple more ideas
 
   / Kubota 1140 CPX Overheating #9  
There will actually be coolant bubbling out the reservoir. Blow the radiator and air filter and problem solved. Temporarily. There is no permanent fix to the problem that I can see. Just a bad design from Kubota on this one. I've had the UTV for 5-6 years. I've just made this part of the routine.
 
   / Kubota 1140 CPX Overheating
  • Thread Starter
#10  
There will actually be coolant bubbling out the reservoir. Blow the radiator and air filter and problem solved. Temporarily. There is no permanent fix to the problem that I can see. Just a bad design from Kubota on this one. I've had the UTV for 5-6 years. I've just made this part of the routine.

UPDATE:

I have recently purchased a new OEM radiator and installed it, thinking the old one was clogged and inefficient as the radiator shop said it could not be rebuilt.

Much to my dismay, the Kubota continued to overheat, so I used my meter and determined that I am not getting 12V to the radiator fan, when the temp gauge is registering in the middle to upper range of the gauge,

For now the work around is running a patch cable from the battery 12V positive to the fan wiring harness and grounding the other lead. With the fan running, the RTV does not seem nearly as likely to overheat.

Now I need to track down the temp sensor, which activates the fan and troubleshoot.

I'm also considering replacing the radiator overflow tank with something more substantial as the plastic cap seems to routinely pop off.
 
 
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