2004 660 Rhino coolant problems

Put the cap back on.

Likely a blown head gasket. What does your oil look like?

Water expands when hot, so if you are overfilling that could happen as it gets hot

However, if it's pushing bubbles or steady sort of violence, it's likely compression pushing past the head gasket. Any milk in oil?

Take your radiator off and see if it’s all plugged up with dirt debris and such. Wash it out

im having same problem ,,ill be following,,,with cap off,i can crank it over without starting and coolant blows everywhere,, pretty sure head gasket

pawdad said:

im having same problem ,,ill be following,,,with cap off,i can crank it over without starting and coolant blows everywhere,, pretty sure head gasket

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I would agree you have a head gasket issue.

Hope you have sorted out your overheating problem already, but in case not, I had a similar issue that wasn't a blown head gasket but instead was a clogged radiator. Had to soak and rinse it for a week before I could finally see through it due to all the accumulated mud, seeds, etc. on the exterior of the radiator. The interior was fine. DO NOT use a pressure washer to clean the outside of the radiator. it will bend the fins. Just use a tight setting on your garden hose nozzle.

Get some of the stuff that is for cleaning house outside ac units. BE SURE to get the stuff for aluminum. After washing my Rhino, I spray this watered down on the radiator and oil cooler. It will foam up. Let it set for a while and rinse it out. It will get a ton more dirt out.

Also if you don't have a shroud for your radiator fan, get one. Why they sold these without a shroud is a mystery. Your bike will cool much better with it. Without it a lot of air gets sucked in between the fan and the radiator instead of going through the radiator. This gets worse when some mud is in the radiator. The shroud forces all the air to flow through the radiator.

I think I will add that to my regular preventative maintenance...any other suggestions?

Good idea. How much do they run and where can I get some?

The ones I used are 30mm wide - 110mm long - 14mm high. Two per side on rad and one pre side on cooler. In hindsight, I should have ordered/put more on the cooler.

Here are a few likely candidates close to that size.

LINK 1
LINK 2
LINK 3
LINK 4

thanks, I will definitely add some to my radiator and oil cooler. how did you attach? What is RTV?

RTV Silicone sealer/gasket maker/adhesive. The RTV means Room Temperature Vulcanising.
I think this is what I used. Really can't remember for sure, that was 15 years ago. LOL\

AMAZON LINK

Any auto parts store can help on this. By now there are probably even better products on the market.

OK, thanks. I guess the silicone sealant doesn't insulate the heat sinks from the radiator or oil cooler too bad or else you wouldn't have seen such good results. Thanks for the info.

garyd321 said:

I think I will add that to my regular preventative maintenance...any other suggestions?

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What ANTNY listed will work, but I use the gallon concentrate and mix it in one of the cheap pump sprayers.

I used this one:

you really need to look at getting a shroud for your fan if you don't have one.