Engine Overheat Issue

ghemmen · 07-01-2009, 05:42 PM

Have a low hour (320) 2006 Rhino 660 in very good condition I just purchased. Had a strange over heat issue this past weekend. Ambient temperature was 103 outside. The boys were trail riding for about an hour with no heavy payload. They called me and said that the Over temp light had come on and the Radiator overflow reservoir was overflowing the vent tube. They shut it down and left it. I went back out to diagnose the issue 30 minutes later. When I started the engine, the overtemp light stayed on on start up but the cooling fan was not running. I let it idle for a minute and the fan cycled on and the temp light would not go off even though the fan would cycle off and on every 30 seconds or so. Got the bike home and flushed the heat fins of the radiator with a garden hose. Seemed to be clear yet the temp light remained on. Exterior temp of the engine was 220- 260F (via a temp gun). Reluctantly sprayed the engine down with water and temp light went out and has not come on again. The boys have been riding a lot since then and the out side temp is getting up to 100 just about every day yet the Rhino has not overheated since. Is there a fan relay in the system that may be malfunctioning or am I off in space.

kodiakrhino · 07-04-2009, 05:41 PM

check the oil. When was it last changed? Also check the thermostat it might be sticking. you can put the thermostat in a pan of water and start boiling it. use a thermometer to verify when it opens. if you find nothing there check the water pump. Be glad you fan did come on.

ghemmen · 07-05-2009, 10:02 AM

I just changed the oil the day before the problem started. Amsoil 0w-40 full synthetic. Also changed to Engine Ice from EG. Had a dirty air filter. Changed to K&N. The Idiot light sender is bad causing the light to blink intermittently. Also burped the system and it had some air at the bleeder. My next step is to install a real Temp gauge so I can see what is really going on. May have to modify the sender port to accept the gauge sensor.

07fj · 07-06-2009, 11:26 AM

Quote:

Originally Posted by ghemmen

I just changed the oil the day before the problem started. Amsoil 0w-40 full synthetic. Also changed to Engine Ice from EG. Had a dirty air filter. Changed to K&N. The Idiot light sender is bad causing the light to blink intermittently. Also burped the system and it had some air at the bleeder. My next step is to install a real Temp gauge so I can see what is really going on. May have to modify the sender port to accept the gauge sensor.

not if you get an guage from iequus.com tell them you need the little sender for a rhino. goes right in stock location, then ground the orig wire to it so the light stays off.

also you can add a tcp (totally cool Products)fan shroud, this helped mine it is about $50 bucks.

for the other poster, there is no thermostat.

kodiakrhino · 07-06-2009, 11:15 PM

That would explain why the fan is suppost to come on at 167 +/- 5.4 deg F and should go off at 154.4 deg F.

Assumptions make assholes out of all of us.

ghemmen · 07-07-2009, 08:53 AM

Thanks 07. Got the gauge at my auto parts store and the little sender fit perfect. The Rhino is running at 180-190. In regard to the other poster I was looking at my service manual and did not see a thermostat in the cooling system. There is a logical place for one between the sender and bleeder housing. I guess the engineers at Yamaha decided that there was so little jacket area in the head that it would not do any thing but stay open all the time.

Lil Foot · 07-07-2009, 12:09 PM

We have found several early ('04 & '05) Rhinos with heating problems that had defective circuit breakers on the cooling fan circuit. The symptoms are overheating, with the fan either running only occasionally, or the fan cycling on/off every thirty seconds or so. The breaker, (which is taped into the wiring harness, near the support for the steering column, under the cowl) gets weak, and when the fan is switched on by the temp switch, the breaker overheats, pops open for about thirty seconds, cools, resets, and then allows the fan to run for another thirty seconds, then repeats. The fan never runs long enough to accomplish anything. The fix is to either replace the breaker with an inline fuse, or some guys just jumper it out completely. If you keep having problems, and the fan turns on & off repeatedly, I would suspect the breaker.

ghemmen · 07-07-2009, 01:48 PM

Great Info

This is exactly what my 06 was doing the one time it overheated to the point the expansion tank vent was overflowing. The fan would come on and go off every 20 seconds or so. The weird thing is that it has not done it again since.

I did remove the idiot light sender with a temp gauge/sender so now I know what is going on. Thanks again you guys are great.

Lil Foot · 07-07-2009, 07:24 PM

A trail fix for a bad temp switch (in the radiator) is to find a crimp-on style spade lug (the "fork" type, not the ring type) that is about the same size as the two prongs sticking out of the temp switch. Then you can just pull the connector off the switch & plug your spade terminal into the connector. This will let the fan run all the time & get you home. I carry a couple in my emergency kit..... saved my bacon once already.

max powers · 07-07-2009, 07:48 PM

when you buy the pwr radiator, part of the install directions is to cut that gel pack out and wire it together eliminating the breaker.