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2004 Rhino 660 Chronic Overheating Issue

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We have owned this UTV since new. Only use it to go hunting a few times a year.

 

It always has run well for us except for last couple of years. So I started off with some basic fixes.

 

One, the fuel pump would lose prime and not reprime, so I replaced with a new Yamaha updated unit. Fixed that problem.

 

Two, the intake was not the updated style on top of the center cover. Bought all the pieces to make that work. Helped with dirty filters and poor performance when it got warm out.

 

Three, wired the fan on a switch that jumps the thermostatic switch. This is for when we are going up washes while hunting. We go about 8 to 10 miles an hour on sandy washes, so airflow was a problem. This helped, but not really.

 

Four, I wasted half a day pulling the fuel tank because my dad insisted that there was slime and goo down in it that was plugging fuel filters. That was fruitless in its entirety.

 

So basically we get a heat problem, and that tends the gas to start boiling and thus vapor lock. Keep in mind this happens on 80 degree days. It's not even that hot out, but the whole entire machine is just so hot you really dont wanna touch it. The motor cover is hot, the radiator is hot, the gas tank is hot. The whole thing is F**NG HOT.

 

It always starts well(just bump the key) and runs well in the morning when its below 60.

 

I'm losing my mind here trying to figure out how this machine used to run so well for so long and now the overheating/vaporlocking problem continues to worsen every time we go out.

 

Anybody have this problem or know where I can start at?

 

Thanks guys!

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So the fan is running all the time, but it's still heating up? 

Might be a failing water pump, there's not much else involved.

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Well upon looking through the parts catalog and other various sites, the rhinos dont have thermostats, so it cant be that.

I remain unsure how to go about checking the water pump. Its mechanically driven, so it should either work or not work. No in between.

I dont think this is a coolant issue. Usually when there is this much heat involved, it has to do with ignition and or exhaust issues.

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You're right, no tstat is shown although the same motor in the Grizzly uses one.

You should check the exhaust alright, any blockage could cause this. Not sure what might be ignition related.

 

 

 

 

 

 

 

 

 

 

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Well, in the interest of my sanity, I did 2 things last weekend.

Unhooked the carb warmer, it doesnt get cold enough any time of the year to justify it. And second I took every single jet out and blasted it clean with carb cleaner.

Also blasted the entire carb out. Appeared as though some orifices and passage ways had been clogged. Given by the presence of the deep yellowish colored stuff that came out of the orifices at I cleaned them.

So i think what happened is that the carb got buildup in some places and this caused it to lean out, in gasoline world, that means hotter engine. It seems to run a bit better and smoother now. Also starts better and has a strong gas odor when cold idling indicating its rich, something it didnt do before.

Moral of this story is clean the carb every couple of years and unhook the carb warmer is you live in the southwest.

I'll post back after our next hunt trip. This will be the true test.

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