Kubota F2400 Overheating - Thoughts Please

[SusanJ]

2200 hrs on Kubota F2400 front mower/72 inch deck.

Hello, hope someone can help me through this.
Between strip screws, broken bolts, etc. my mower's been down awhile. Mower Overheating (in 20 minutes) issue when on load, can idle all day long!

What I did...
Oil change, (old oil looked black)
Replaced thermostat, water pump and fan belt.
Flushed out with water, all hoses and radiator/inside & out
Washed down the whole darn thing.
Still overheating

Tractor took a trip to local Kubota dealer; what they said they did...
Fixed 4wd not engaging correctly
Flushed radiator/system?, twice.
Install 3 new blades.
Still overheating,,,,also a blade fell off!!!!!Really!

Then a friend...
Took Radiator off, went to local radiator shop, totally re-cored, re-installed.
Still overheating
Ugh

Thoughts, besides buy a new mower?

 

[pmsmechanic]

So what does overheating mean? Is there bubbles or antifreeze blowing out the overflow? Can you hear the antifreeze boiling in the rad or engine? Or....is the temperature gauge or light just showing hot?

Buy an infrared thermometer (25-30 USD) and point it at the thermostat housing. You'll be able to see the temperature that the engine is running at. This will show you if you really do have an overheating problem or if your gauge/light is lying to you.

 

[SusanJ]

It's very hot, blowing antifreeze out whistle.
Sounds like it's close to boiling in radiator.
Temperature gauge is showing hot.

same symptoms before and after core radiator replacement.

 

[JOHNTHOMAS]

Looks like the "new" water pump or thermostat you installed may be bad. I'd start with a new thermostat or remove thermostat to see if it makes a difference. Appears it's no longer the radiator, with all you've done to the radiator already, if it ever was the radiator. Sure you also have several new installations of new anti freeze 50/50 solution with all the flushes. All I can possibly see is the water pump or thermostat you installed was/is bad or fan belt isn't turning water pump so could be belt is bad or wrong one/size.

 

[arto98607]

It's very hot, blowing antifreeze out whistle.
Sounds like it's close to boiling in radiator.
Temperature gauge is showing hot.

same symptoms before and after core radiator replacement.

Is the cooling system (radiator) pressurizing as it is supposed to do? That will increase the boiling point.

I think standard radiator caps are rated to hold around 14 psi or so.

I would replace the radiator cap.

ptimist:

 

[teg]

I had a Scout II that over heated a lot. I removed the thermostat and ran her without one for years and years.

Getting a new cap is a good idea too.

 

[pmsmechanic]

I wonder if the head gasket is leaking or a cracked head. You've done all the normal repairs and it sounds like there has been virtually no difference in the symptoms.

Leave the rad cap off and warm up the engine. Once warm then stretch a balloon over the radiator neck. If the balloon keeps expanding it's a pretty good indication of a coolant leak.

 

[Spanner]

A lot of money being spent here based on "Hope" and "Guess" without any diagnostic effort at all.

Water-pump replacement - Tested? You can 'see' coolant flowing in the radiator header tank. Did the coolant flow improve with a new water-pump? I suspect no-one checked?
Fan belt replaced? Was it cracked/frayed/slipping? For the purposes of the O/heating diagnosis if the belt is turning the water-pump and not squeeling it is ok for now.
Thermostat replaced? Was it tested? Did it Pass/Fail the opening/closing temperature test?
Flushed internally - Very good.
Cleaned fins?How dirty/blocked were the radiator fins??? (This is important because it leads us to 'pmsmechanics' thought re head & gasket.)

Disappointing that your dealer service was not satisfactory. $ spent? (All the above tests should have been carried out by the dealer plus a pressure/leak test.

Further disappointment that your friend incurred the cost of a re-cored radiator without any of the above diagnostic. It's had 3 x flushes already. $$$ ?

And you still have overheating...

You have: a new thermosat, water pump, fan belt, coolant and a re-cored radiator. MAybe even a new cap in there somewhere? There is not much else in the cooling system to replace so...

You need to check the areas that can induce heat and pressure into the system which includes the cylinder head, the gasket which seals that to the block and even the block itself if that proves necessary.

A test for combustion gas in the coolant is cheap & easy. (Carbon Monoxide test). That and a pressure test to check for loss of pressure will guide the diagnostic further.

Testing, Testing, Testing.
Test, Prove & Move.
Test a component, Prove it is functioning, Move on to the next component... saves a lot of money.

 

[kthompson]

Will it overheat if your run it at operating speed without the blades engaged? But have you checked the air intake system for restriction or even changed the air filter? That will cause one to run hot. No idea what kind of hyd system is on that machine but you may have a valve that is not set right.

 

[Brown Dog]

I had a Scout II that over heated a lot. I removed the thermostat and ran her without one for years and years ...

I couldn't keep my 4700 JD Tractor cool mowing grass every week.
I removed Tstat against everybody's advise, & it's ran flawless all season long