rtv 1100 overheating problem

[Hersheyfarm]

Your the guy with the M59 and hyd. problems. What a bummer, sorry for you to have been dealt 2 crappy Kubotas. All I can say is sorry from a loyal Kubota owner and someone who has many Kubota products including an RTV1100. I have never seen my temp fluctuate, ever. Rarely do I hear my fan come on, only in summer when hot and extended use. Good luck.

Thanks. My fan kicks on at a 1/3 mark on the gauge and kicks off at about a quarter. I have 2 dots on the clear cover I made with a marker. My needle bounces back and forth, without the fan working it would overheat quickly.

 

[Hersheyfarm]

so I picked it up today. They did a pressure test on coolant system and said no leak. Did compression test and all cylinders tested at 350psi. At first, while they where waiting on part for their compression tester they where talking like it should be around 425psi. Kubota said compression is within spec. so I guess I keep watching it. I really made sure it was leaking off mainly because its a 2 hour round trip. Ill keep running it and watching coolant, but it defanantly dropped, more than half of the coolant jug twice. who knows.

 

[texasjohn]

very vexing. I can only tell you that we have a diesel Mercedes Sprinter. Same story. Loosing coolant, verified multiple times. No obvious leaks. Dealer did coolant pressure test...held pressure. Could drive from Fla to Texas and not use coolant. A month of stop/go daily driving in Texas...had to add coolant several times. Seemed to be related to the number of cool/heat cycles. I finally added radiator stop leak...been 7 months now, no need to add more coolant.

Vexing...no real answer, dunno how long the stop leak will work...however, I have had good luck on a couple of other occasions with it, so am hopeful.

 

[Hersheyfarm]

very vexing. I can only tell you that we have a diesel Mercedes Sprinter. Same story. Loosing coolant, verified multiple times. No obvious leaks. Dealer did coolant pressure test...held pressure. Could drive from Fla to Texas and not use coolant. A month of stop/go daily driving in Texas...had to add coolant several times. Seemed to be related to the number of cool/heat cycles. I finally added radiator stop leak...been 7 months now, no need to add more coolant.

Vexing...no real answer, dunno how long the stop leak will work...however, I have had good luck on a couple of other occasions with it, so am hopeful.

Thats interesting about the heat/cool cycles. As the engine heats up and tightens up the leak stops, quick short trips that run cool burns coolant.

 

[texasjohn]

Mercedes has 100,000 miles, yours has less than 100 hrs.

My best guess...tiny gasket leak somewhere...Dunno if there are any bolts that could be torqued down to solve problem without tearing into engine...ask dealer if they will void warranty if you use stop leak....or maybe not mention it....vexing!

 

[DDM84]

do you work on alot of rtv's? Have you seen many of these sensors fail? In a perfect world there would be an emergency circuit wired in so when the guage hits the red it kicks fan relay on, that and a warning light.

I have worked on quite a few Kubotas and that particular temp sender is known to fail more than others. It is used on a few other models in the compact segment of the Kubota line up and is kept in stock for that reason. It has been a while since I have worked on an RTV but if my memory serves correctly that sender serves purely as a switch for the fan. There is a second temp sender for the gauge. If the fan ran off of the temp gauge sender it would need to toggle the fan switch at a certain resistance that correlated with the max temp. The RTV electrical system is just not that sophisticated and therefore relies on the other temp sender switch. In many respects that is a benefit on a machine that is used in such rugged terrain and climates. Mechanical durability greatly outweighs computer durability in those applications. However and unfortunately this particular switch hasn't kept up with the quality and durability of the rest of the RTV.

 

[Hersheyfarm]

I have worked on quite a few Kubotas and that particular temp sender is known to fail more than others. It is used on a few other models in the compact segment of the Kubota line up and is kept in stock for that reason. It has been a while since I have worked on an RTV but if my memory serves correctly that sender serves purely as a switch for the fan. There is a second temp sender for the gauge. If the fan ran off of the temp gauge sender it would need to toggle the fan switch at a certain resistance that correlated with the max temp. The RTV electrical system is just not that sophisticated and therefore relies on the other temp sender switch. In many respects that is a benefit on a machine that is used in such rugged terrain and climates. Mechanical durability greatly outweighs computer durability in those applications. However and unfortunately this particular switch hasn't kept up with the quality and durability of the rest of the RTV.

Those fan switches are 100% liable for what temp your motor runs. the cooling system is small on these and obscurely placed but when the fan kicks on the temp drops quickly. So if anyones rtv seems to run hot I'd be looking at this switch.