Kubota engine cooling problems

[BMXER10]

My g5200h is acting up again. I just changed the oil, tranny fluid, and all filters including air filter.

I changed the radiator fluid to a 50/50 mix and also added water watter. The tractor slowly heats up until its overheated. The radiator fins are clean on the outside, & the fan is spinning fine.

Could this be the thermostat or the water pump? Could I test both of these things at the same time by taking the cap off the radiator and letting it heat up to see if its flowing?

 

[Soundguy]

Get a couple buckets and a garden hose...

Pull the top hose off the radiator and aim over to the bucket.. start her up..

See what you get.

Soundguy

 

[schmism]

what happens when you let it idle for say 30 min?

does it heat up?


id vote for thermostat

 

[BillyP]

My g5200h is acting up again. I just changed the oil, tranny fluid, and all filters including air filter.

I changed the radiator fluid to a 50/50 mix and also added water watter. The tractor slowly heats up until its overheated. The radiator fins are clean on the outside, & the fan is spinning fine.

Try looking through the radiator fins with a flashlight.

 

[Egon]

Water pump failure is usually the shaft seal and bearing failing allowing water to leak to the outside. Chances are your water pump is fine if there are no leaks.

The fan belt may be loose allowing the fan or pump to slip.

The radiator has to be clean outside and on the inside. Sometimes they have to flushed properly to get rid of internal debris.

A hose may be old and collapse thus not allowing water to circulate.

The thermostat can fail. Remove and place in boiling water to see if it will open.

Radiator cap may not retain sufficient pressure for proper cooling.

There may be an internal exhaust leak into the cooling water system which will cause overheating.

And ???

 

[cp1969]

Water pump failure is usually the shaft seal and bearing failing allowing water to leak to the outside. Chances are your water pump is fine if there are no leaks.

I had a 3.0 V6 Ford engine in which the fins of the impeller corroded away, leaving it just a whirling disk. Didn't leak to the outside but caused all kinds of cooling problems.

If you can rule out the water pump and thermostat, I would check the radiator. It may be clogged up internally.

 

[J.Walker]

I'd start with cleaning the three outside air grills that are between you knees as you sit on the tractor. Use soap and water and a nylon brush. The grills should be Kubota orange not black.
Blow out the area between the grills and the radiator.
Try cleaning the fan blades too. They get built up with crud. They should be a nice nylon white color.
Edon brought a good point about the radiator cap and pressure. Check the rubber seal on the backside of the cap it maybe all puffed up.
How many hours does your tractor have on it now?
My G6200 is past 1500 hrs now.
Don't let this problem get the best of ya.
Their great lawn tractors.

 

[ozzie tractor]

my money is still on the radiator. they may look clean but are still partly blocked. soak it with degreaser and then hose it out. make sure water flows through it all over the core. the hard to get to places sometimes get missed. especially the corners. i have also seen oil and exhaust soot build up on the fins, you could still see light through the core but it was really fairly blocked.
also the one issue no one has mentioned yet is overloading. how hard are you pushing this machine. dont say same as always either because as a engine gets older it may drop a hp or 2 and it can suddenly be overloaded doing what it did before. to rule this out try when working normally to go just a touch quicker. if it handles it without dying down it is not overloaded. simple hey. i had this once with a guy who flatly refused to mow his block in low because it always did it in high. it went on for ages

 

[BMXER10]

I went to install the new thermostat and surprise surprise there wasnt one in there at all. I was told this could be the problem because the water doesnt stay in the radiator long enough to cool it. Is this true? It ran a click cooler on the temp gauge now, but I ran out of grass to mow before I could run it as long as I usually do.

 

[SkunkWerX]

I went to install the new thermostat and surprise surprise there wasnt one in there at all. I was told this could be the problem because the water doesnt stay in the radiator long enough to cool it. Is this true? It ran a click cooler on the temp gauge now, but I ran out of grass to mow before I could run it as long as I usually do.

But, from a troubleshooting standpoint, it doesn't explain why NOW it is overheating? Still has to be something else affecting it, as the assumption is that it has been operated without a thermostat since, well, for a while?

It's likely that the thermostat issue played a part.

Back to things like belt tension and radiator cleaning?

Also, if it's only happening when mowing, does the mowing deck or PTO have a problem which is creating a larger-than-normal load on the engine? example: siezing spindle, overtightened deck belt, grass clogged underneath?

Any of these types of problems could be loading the machine to the point of overheating.

I'd suggest giving it a visual all the way around, including underneath the mower deck.

Once you have proven the water-pump as good, I might consider a full flush of the cooling system and use a "wetting" agent along with your mix. Sometimes 50/50 is not what the maufacturer calls for, just check the manual to be sure.
Sometimes they will recommend various ratios for extremely hot or cold weather.

That's all I can offer at the moment.