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Discussion Starter #1
My 625 XUV Gator is a 2014 with 125 hours on it. 12 months ago I experienced overheating conditions leading to erratic engine speed and eventual stalling. $175 dollars later the nearest dealer replaced the thermostadt and the vehicle performed satisfactorily. Recently the vehicle is displaying the same symptoms...stuttering performance, over heat dash light comes on, cooling fan comes on, engine stalls. After cooling down ( air temps in the high teens doesn't take too long) engine started normally and I limped it back to my storage location.

Nearest dealer is 60 miles away so repairs start with a $100 flat bed ride. I am assuming that I am dealing with either another failed thermostadt or possibly a failed water pump. Two questions...how can I "test" the thermostadt and water pump to determine if either is at fault and is the replacement of either of these items something a not very mechanically inclined owner should attempt myself?

Thank you
 

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Testing thermostat is easy.

Remove the thermostat and place in a pot of water along with a thermometer (candy thermometer works well). Slowly increase the temperature while monitoring the thermostat valve. Note when it begins to open and fully open. It's rare these days that the thermostat fails closed. They usually are designed to fail open requiring longer warm up times.

Before doing the above, perhaps do this.

With the radiator cap removed (follow all safety precautions when removing), run the engine until the fan kicks on. Pay attention to see if and when coolant is flowing in the radiator.


Good luck and post back what you find.
 

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Discussion Starter #3
200 MPH...thanks for the tips...If I remove the radiator cap and follow the directions and do NOT see any coolant movement how does that tell me whether the thermostat or the water pump is at fault?

Shink4
 

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If you get no flow, you'll need to evaluate one or both (thermostat or water pump). While it can happen, I'd be very surprised that you've experienced two failed closed thermostats. Like I said earlier, most modern thermostats are designed to fail open.

Another possibility is that you have trapped air in the coiling system or a pinched/collapsed hose. If air is suspect, jack the front end to elevate the radiator inlet with respect to the rest of the system to help get the trapped air to move.

If the water pump is belt driven, check belt tension to see if it is tight. If tight, remove and spin the water pump by hand. It could be the pump is seized and the belt is slipping on the pulley. It's also possible the impeller might not be connected to the shaft.

Is your cooling fan coming on?
 

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Discussion Starter #5
Yes..the fan comes on but just before the engine starts to stutter and stall. I agree that a second failed thermostat is unlikely. The vehicle normally is idle between December and March due to winter conditions in northern Wisconsin that also makes messing with it in an unheated shed an unpleasant assignment. Will likely let it be until warmer weather in March and take up the issue at that time. Thanks again 200mph for the hand holding.
 

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I know you don't have a 825I, another way to test your thermostat is to connect it to a multimeter and check the resistance when cold then let the machine run and verify the resistance changes when the engine overheat light comes on. The thermostat sends and open or closed (continuity or no continuity) when it opens and closes. Another option is to just hold your hand on the hose that connects between the thermostat and radiator when cold, then start and see if the hose warms up when the engine is warmed up.

Check to see if you have a air bleed valve in the water system (on the 825I it is in the hose on top of the engine), with the engine off crack open the valve until you get water coming out then close.
 

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As stated before, "burp" your coolant lines. These things are very susceptible to air pockets since the water pump is very close to the water level at the top of the radiator. Any drop in the water level results in an air pocket at the WP. Topping off the radiator doesn't necessarily remove the air pocket. It has to be vented at the WP. The water pump is not self-priming.
 

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Discussion Starter #8
I do not have ready access to the vehicle or the owners manual. Can someone tell me if the manual illustrates where the coolant line "air bleed value" is located? Is this valve accessible without having to tear off other engine parts?

Thanks to all in advance.
 

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In the manual linked above look for the coolant section. There is detail and picture of how to bleed the air.


1. Remove bleed screw (J) and seal washer located on intake manifold (K).
2. Remove radiator cap and add recommended coolant mixture to radiator until coolant runs out of bleed port.
 

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Discussion Starter #11
200mph...very helpful...thanks again...Brad
 
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