Overheating RTV900

[Duckhunter]

This past weekend we did some trail riding with the RTV900 bought in June of 2007. On any hill climb the temp gauge would go up to almost in the red but come down to 3/4 the way over on flat roads. Upon looking, the cooling fan is NOT coming on. In the summer when idling I hear the fan come on occasionally. Now there is no fan at all when almost in the hot zone.
I checked fuses, wiring connectors etc... Any ideas or previous history with this problem?
Great machine with no major issues so far except a scraping rotational sound from under the front end. Any ideas on that one?

 

[Eagleview]

Now there is no fan at all when almost in the hot zone.

Great machine with no major issues so far except a scraping rotational sound from under the front end. Any ideas on that one?

Crook fan motor bearings , damaged fan blades , stick in fan causing both problems ?

 

[SnowRidge]

There should be a thermostatic switch somewhere. It may be defective or stuck. If it has only two contacts (or one plus ground), try shorting around it. The fan should come on indicating the switch is the problem.

I have also seen a similar problem caused by low coolant level.

These are generic suggestions. I don't have any direct experience on the RTV900.

 

[Wayne_H]

Are you sure the fan is not coming on? There are two fans on the 900, one is electric near the radiator, and one is on the enigne, belt drive. My 900 the temp ALWAYS goes almost to the red, then the fan comes on and it drops to 3/4 or so. I have checked it myself with a temp probe and it is not over heating, and the dealer checked it also. I'll bet is is not overheating, unless you smell something or see signs of overheating.

wayne

 

[Duckhunter]

It does smell hot and the fan spins freely with no obstructions. When I say close to hot, it is a needle width away from the red zone. The electric fan is not coming on but has in the past with the temp gauge lower than it has been.
I was hoping to find out where the temp sensor was so I could check for unplugged wire or something simple. It only has 155 hours with no abuse.

Thanks for the replies...

 

[Nwood]

http://www.tractorbynet.com/forums/...-temp-gauge-problem-794434-763011-coolant.jpg

 

[pappy19]

I noticed that when I took out the screen in my mufler, the engine temps dropped and it ran better. Also, the snorkel air cleaner makes the engine run some cooler as well.

 

[TWO GUNS]

I know you have done this, but gotta say it.... Check the water level, pull out the protective screen and wash out the flums of the radiator really good.
Few months ago, keep looking at the screen, and it really looked clean, THEN, for some reason, I decided to remove, and dammmm ~~ about 20% of the bottom of radiator was clogged up with dirt and mud. Don't ask how one could not see it, but couldn't unless the screen was removed.
check the thermostatic switch on the fan motor ~~~~
Raise bed, and wash out radiator backwards !!!!

 

[Jason537]

You want a quick way to check the radiator fan, pull the wire off the sending unit at the thermostat housing and ground it, if the fan comes on the your wiring is fine.

The gauge has no affect on the electric fan as they are wired separately.

 

[arkansasdelta]

I've had my Kubota 900 for 6 or 7 years and usually have problems with it overheating when I'm towing any implement with some drag. I talked with a buddy in sales who told me the heat from the hydrostatic motor combined with any impediments to the radiator are a continual problem with Kubota RTVs. He said even some of the newer models with bigger radiators have the same problem due mainly to the heat from the hydrostatic pump. If I'm in grass or vegetation with light fluffy, seed heads, it will heat up quick if you don't keep the screen clean. I love my 900 and the overheating is the only shortcoming for me. I'm open to any ideas on how to better fight the heat!

 

[SpudHauler]

arkansasdelta
I would, change the thermostat, change the coolant using a good brand name like Prestone and flush the system before adding the new coolant. Then do as suggested earlier and clean the rad fins.

And if you want some control, add a wire to the one going to the thermostat by splicing in and run it to one side of a switch. The other side run it to ground. Place the switch beside the emergency handle somewhere, that way it will be easier to wire in because it's closer to the engine and now you will have a manual controlled fan. Switch it on when things get too hot or let the thermostat do it, it's your choice. Both will work because each is just a ground but the switch will give you control on when you feel the fan should or could be on.

 

[Wayne_H]

stop over worrying!! My 900 did the same thing, then I took out the POS gauge and installed an Isspro gauge, and realized the "almost hot in the red" was really 195, right where it was supposed to be.,..

Wayne

 

[rjrhoades]

I am not getting power to the fan (fan is free and radiator is clean). When I ground temperature sensor wire at motor, temperature guage swings all the way over but the relay does not trigger and I do not detect any appreciable voltage at relay coil terminal - only 0.70 volts that does not change whether meter is pegged or not. How much voltage does it take to activate relay (I was assuming 12V).

 

[SpudHauler]

Perhaps this will help.

1= RG red/green to relay should have power all the time with key on. 12v reading here. This is the power into the relay to activate it's switch when the temperature sender reads engine temps that are too high and grounds out. So low voltage or no voltage and the relay will not work. Possibly bad fuse or bad wire feeding the relay.

2= RL red/blue to relay should have power all the time with key on. 12 v reading here. This power gets sent to the fan when the relay is activated, like when the pink wire is grounded. Low or no voltage here is bad fuse or bad wire.

3= P pink to coolant temp switch should be equal to a ground, so touch it to anything grounded and the fan should come on or at least show power to the RB red/black wire going to the fan, when key is on. If fan comes on and it doesn't when engine is too hot, bad temp sender.

4= RB red/black is power to fan when temperature sender reads high or pink is grounded. Low or no voltage here and relay is bad.

5= B black from fan is ground so touch it to ground if unsure it is grounding and with key on, pink grounded, fan should come on.

If you have 12v on RB (red/black) when P (pink) is touched to ground and no fan, fan is bad. Or remove fan and touch wires directly to battery to see if it still doesn't work just to be sure.

You need to be able to read voltage not just if a test light comes on. So a voltage gauge is necessary to test this properly. Relays require 12v to work properly and fans do as well. Check battery voltage while you are at it.

Good luck.