Let my 800 idle for about 10 mins yesterday and when I looked down at the dash it was 1 bar under top temperature. As soon as I moved it started going down immediately. I then went for about a 10 mile ride and no issues, fan was working fine etc


Any ideas if I could have some type of issue or maybe just a faulty temp reading from the sensor? If there's a problem I'd like to get ahead of it before I end up stranded.


I was going to start by checking coolant level, cleaning the rad the best I can without removing it with a pressure washer and check
From there.

Any tips on stuff to
Look for?

I should add as well coolant into he tank right now is just slightly above the lower fill line maybe by half an inch.

[2015 Z Force 800 53/Trail EPS]

When the gauge was showing the high temperature, was the fan running? BTW, never good on any machine to idle for long periods.

Nope fan wasn't running which is what I found weird. My fan always works fine and did all night never went above 3 bars when riding.

So the coolant in the radiator wasn't getting hot enough to trigger the fan until the engine ran fast enough to pump the coolant through.

Is it repeatable?

Radiator full (pull the cap)?

If so, check the thermostat for full open. If that checks out, then time to look at the pump.

How old is the machine? How many miles?

Don't use pressure washer on the rad as it will bend the little fins, just use air from the back.

so i just got back from giving the rad a good wash. it was pretty caked up espeically around the plastic honeycomb pieces. I let it idle for about 10 mins and sure enough temp climbed again almost to the top, but the fan did not kick in. i then went for a short ride. as soon as i got moving temp dropped to two bars fan came on at 3 or 4 bars as it always does. it seems to just be an "issue" at idle. what would stop the fan from coming on when its idling in park? is this by design? It doesnt seem right but i cant ever recall a time since i owned it that it would have idled long enough to need the fan to come in so it may have always been this way im not sure...

Not sure if this applies to your machine or not but ...

I recall that there was a breaker/relay type thing in the harness that was located on or near the top of the radiator. It's job was to protect the fan motor.  That device would not pass current when it got hot, which would happen because of its location on the top of a hot radiator, and the fan would not spin as a result.

I thought the fix for that was to replace the breaker with a fuse.

This was something added in recent years.

Not sure if this applies to your machine or not but ...

I recall that there was a breaker/relay type thing in the harness that was located on or near the top of the radiator. It's job was to protect the fan motor.  That device would not pass current when it got hot, which would happen because of its location on the top of a hot radiator, and the fan would not spin as a result.

I thought the fix for that was to replace the breaker with a fuse.

This was something added in recent years.

interesting. do you have a pic of the harness or fuse?

[2015 Z Force 800 53/Trail EPS]

This behavior suggests that at idle the flow through the thermostat isn't enough to bring enough hot coolant to it to open...thus not enough to the radiator to trip the thermoswitch. As the radiator is staying cool, the fan switch has no reason to come on but the temperature sensor,.. which is before the thermostat says it's overheating. Now either the little bleed hole on the thermostat is plugged, the thermostat itself has a problem...or the water pump has lost it's ability to pump at slow RPMs. It could also mean there is an air pocket in the top end somewhere. I would lean toward a pump or thermostat issue.

Something else I found when looking around was that.. I can't find where CFMoto made a CForce 800 in 2018. They made then up to 2017, not in 2018 but introduced the CForce 800 XC is 2019. Maybe they only made them for the European market...but I don't see them anywhere...even with CFMoto. So I don't think this is a 2018 CForce 800. I think it's a 17 sold as an 18. JMO

This behavior suggests that at idle the flow through the thermostat isn't enough to bring enough hot coolant to it to open. As the radiator is still cool, the fan switch has no reason to come on but the temperature sensor, which is before the thermostat says it's overheating. Now either the little bleed hole on the thermostat is plugged, the thermostat itself has a problem...or the water pump has lost its ability to pump at slow RPMs. It could also mean there is an air pocket in the top end somewhere. I would lean toward a pump or thermostat issue.

Something else I found when looking around was that.. I can't find where CFMoto made a CForce 800 in 2018. They made then up to 2017, not in 2018 but introduced the CForce 800 XC is 2019. Maybe they only made them for the European market...but I don't see them anywhere...even with CFMoto. So I don't think this is a 2018 CForce 800. I think it's a 17 sold as an 18. JMO

Its a 2017. i was thinking of changing out the temp sensor on the rad but maybe that wouldnt help?

I have no picture.

As my memory clears, my brother had the same issue (I was with him when it overheated at Pisgah State park). His XC had the breaker, and the dealer replaced it with a fuse. I believe it is located on the right hand side near the top of the radiator.

I'm pretty sure they started using these on the XC versions, but it's worth checking. It certainly is not on my 2017 Z8.

I'm in agreement with Clark. Low flow at idle keeping the engine hot and the radiator cool until engine RPMs increase.

[2015 Z Force 800 53/Trail EPS]

This behavior suggests that at idle the flow through the thermostat isn't enough to bring enough hot coolant to it to open. As the radiator is still cool, the fan switch has no reason to come on but the temperature sensor, which is before the thermostat says it's overheating. Now either the little bleed hole on the thermostat is plugged, the thermostat itself has a problem...or the water pump has lost its ability to pump at slow RPMs. It could also mean there is an air pocket in the top end somewhere. I would lean toward a pump or thermostat issue.

Something else I found when looking around was that.. I can't find where CFMoto made a CForce 800 in 2018. They made then up to 2017, not in 2018 but introduced the CForce 800 XC is 2019. Maybe they only made them for the European market...but I don't see them anywhere...even with CFMoto. So I don't think this is a 2018 CForce 800. I think it's a 17 sold as an 18. JMO

Its a 2017. i was thinking of changing out the temp sensor on the rad but maybe that wouldnt help?

Might change your signature to reflect it's a 2017. Nope, changing the thermoswitch won't help. Do this again but this time with the radiator cap off and feel the coolant temp when it reaches 4+ bars. It should be 225+F.. so hot you can't stand it. If its cool..or just warm you know you have a circulation problem.

I did as suggested with the cap off. It was Definetly hot. After doing this I actually couldn't replicate the problem, I also noted the fluid in my reservoir now that it's cold a few hours later has dropped nearly an inch to below the lower fill line.

Is this indicative of an air bubble in the system that maybe burned out when it ran with cap off? Maybe this was the problem all the while?

[2015 Z Force 800 53/Trail EPS]

I did as suggested with the cap off. It was Definetly hot. After doing this I actually couldn't replicate the problem, I also noted the fluid in my reservoir now that it's cold a few hours later has dropped nearly an inch to below the lower fill line.

Is this indicative of an air bubble in the system that maybe burned out when it ran with cap off? Maybe this was the problem all the while?

An air bubble or pocket has been known to cause problems like this. Let's do it again except this time have the front end off the ground about 6". Run it until the fan comes on, then top-off the radiator to the very top..NO air gap and put the cap on. Then fill your recovery bottle to the high mark. Then take it for some runs. Oh, also check the oil. Make sure it's not over full and not milky at all. A leaking head gasket can do weird things too.

Just general info- if the fan switch..or thermoswitch is NOT covered by coolant...as in the radiator is low, it will not operate. If the coolant level is just below the switch at idle the higher flow rate from faster RPMs will cover it and allow it to work. This might be what was going on. The switch is near the top of the radiator and if it's down too much..it will be uncovered.