Yamaha Grizzly 350 Overheating


Why Does My Yamaha Grizzly 350 Overheat? After about 30 minutes of driving the engine becomes too hot and the and the temperature light illuminates. The unexpected rise of temperature makes it very frustrating because I need to stop the vehicle and let it cool down.

What’s odd is that sometimes the temperature light never comes back on. 

I recently did an oil change, put in a new oil cooler and put in new spark plugs. It was about a week after I serviced the ATV when the 4-wheeler started running too hot. Any one with similar experiences or suggestions? What would cause a Yamaha Grizzly 350 to overheat?

My four-wheeler is a 2008 Yamaha Grizzly 350 4WD.

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Benjamin Yue 3 years 2020-12-01T18:21:55+00:00 2 Answers 1616 views Beginner 0

Answers ( 2 )


    There are a variety of reasons why your Yamaha Grizzly overheats, the most common 3 are a result of engine oil, oil cooling system and ignition system.

    The factory manual list more than a dozen possible causes for a Yamaha Grizzly having a high temperature. Here is what the manual suggest you check if the engine is overeating:

    Ignition System

    • Incorrectly gapped spark plug. Set gap to 0.024 ~ 0.028 in.
    • Incorrect spark plug heat range. Use DR8EA/NGK.
    • Defective CDI unit.

    Oil Cooling System

    • Malfunctioning thermo unit.
    • Fan motor relay not working.
    • Radiator fan motor circuit breaker defective.
    • Oil cooler damaged or clogged.
    • Fan motor inoperative.
    • Defective CDI unit.

    Brake System

    • Brake drag, pads not releasing completely.

    Engine Oil

    • Oil viscosity too thick.
    • Inferior oil quality.
    • Oil level too low.

    Compression System

    • Excessive carbon build-up.

    Fuel System

    • Dirty or blockage to air filter element.
    • Carburetor main jet setting incorrect, running lean.
    • Improper fuel level.

    There could be other reasons why the all-terrain vehicle is overheating. In fact, have you verified that the vehicle is actually running too hot? Maybe it’s not running warm at all. Check the wiring to the overheat light, maybe they are frayed or damaged.

    Best answer

    One of the most common overheat problems on some Grizzly models is a blocked/muddy radiator. Also, if the wiring connection came loose from the temperature sender the temp light will come on. Have you seen coolant bubble out yet?

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