2008 700 Overheat issue Help!! - Yamaha Rhino Forums - Yamaha UTV Forum
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post #1 of 2 (permalink) Old 08-05-2012, 02:55 PM Thread Starter
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2008 700 Overheat issue Help!!

So I'm having an overheat issue, let me give you some background and I hope you might have some suggestions!!

In January I bought a used 2008 700. It seemed to run ok the 15 minutes I ran it, and the guy seemed honest. Well... It had a blown head gasket. Not being real familiar with the engine, I took it to be repaired. They replaced the blown gasket, but some new piston rings and cylinder rings on, also repaired a stripped cylinder stud or bolt. When I got my old parts back, I noticed the thermostat they took out was physically damaged. It seems as if the post in the middle, where the unit opens and closes, has some type of plastic that it's made of, and it seemed to have melted out. I know that's hard to understand, but if you can imagine the thermostat in it's full open, full flow position, the post in the center was kind of bent, and plastic was melted out of it. So of course they put a new one in. Well I got it back, it was February. So all seemed well till late April, buy then I had say 20 hours on the repair. Here in Florida, the temprature gets warmer then, and it seemed to affect me, on a ride where we were stop and go I'd see the overheat light come on, and boil some small amount of coolant off. If I let it sit 5 minutes, it would cool down quickly. So I bought a temp gauge kit from Black Rhino, and found out that my fan comes on at 210, turn off at 180, but when it's hot out, and riding a little harder or faster, the system can't keep up and it creeps up to 250 and the light comes on. So it seemed like maybe the thermostat was bad again, I took it out, same things, plastic melted out of the center post, and it was jammed open. So I put a new one in, made sure to bleed the thermostat housing, make sure it was topped off and went out again this weekend. During the heat of the day she would creep up and turn the light on. Evening rides it would creep up to maybe 215 or 220. Keep in mind, when the gauge says 210, the coolant at the cap opening of the radiator is 10 degrees cooler, 200.
Any thoughts?? There seems to be decent flow when I look in the radiator. Is there an aftermarket thermostat that won't fail? I don't mind buying a larger radiator, but I want to make sure I'm not band-aiding a bigger problem...and I wonder who everyone recommends or has experience with in regards to the larger radiator?? Thanks for your thoughts and help with this!!
jdshort98 is offline  
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post #2 of 2 (permalink) Old 07-08-2014, 05:42 PM
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Join Date: Sep 2013
Posts: 3
I'm going to resurrect this old post from jdshort98 being that it pretty well describes the same overheating issues and thermostat failures that I am experiencing with my 2009 700. The first thermostat I replaced did have the plastic piston, as he describes, but this last one I installed appeared to be much better made and I was thinking it would last a lot longer, NOT!

Being that others have seen the same overheating problems (online forums everywhere), one has to wonder if Yamaha has under rated the thermostat being used. Thus the same question that jdshort98 posed, is there an aftermarket thermostat for a 2009 Rhino 700 that I can purchase, possibly with a higher opening temperature rating?

I located a part number stamped on the last failed thermostat and found that it is manufactured by NTCL (Part# NTCL52^C). The 52 degrees Celsius stamp designation on the thermostat converts to 125.6 F. So if the normal operating temp for a 700 is between 180-210, or somewhere around that, why is the thermostat rated to open at such a low temperature?

I've e-mailed NTCL asking them about the wide-open jamming issue, not looking for them to replace the thermostat, but to get there view on what would cause a thermostat to continually fail in this manner (possibly under rated, maybe). IF and when they reply I'll update my post with their reply.

Any help from you guys/gals will be greatly appreciated as well!

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