i heard about having a bad cap, it will do you dirty. the cap looks good but it will have you run in those high temP # . i use WaterWetter - 12oz - and the rest distilled water(thanks raylee for the tip on distilled water) it drop 1/4 on all areas on my gauge. even between the legs have been feeling a lot better in traffic, but come the colder months ill be going back to antifreeze.

 

My fan cuts on at about the half way margin! Check your cap to see if it needs changing!

 

I would agree with SmokinJeff, it's probably the cap. Keep in mind that the temperature you read on your gauge is in no way tied to how hot or cold your engine is running. I don't mean that it doesn't display the engine temperature, it does, but the systems are independent of each other. Changing the thermo-sensor won't change anything. Engine temperature is controlled by the Thermostat and how it allows the coolant to flow through the engine. That, along with the radiators ability to cool the coolant. If the radiator cap can't maintain the right pressure, it can boil over before the other components are able to do their job.

 

If the bike stays cool in traffic with the fan running constantly then it might be worth checking the sensor.

 

I understand how the system works, as well as how the thermostat works. However, the fan is controlled by the sensor,so if the sensor is bad the fan won't kick on. The thermostat is really just a valve that allows the engine to regulate how much water goes into the cooling system at any given time. So, for an engine with a working thermostat to overheat, the thermostat would be completely open, and then its obviously a problem with the rest of the cooling system. Considering that it overheats before the fan kicks on, it has to be a problem with the sensor/switch setup. If the cap was allowing air into the system it would boil over faster, but the fan would be on constantly since it would detect that the engine temperature was above 190 (or whatever temp the fan kicks on at). Since that isn't the case, and with the fan always on, its unlikely that there are any air leaks.

Does anybody know roughly what temperature different positions of the needle on the temp gauge correlate to?

 

Bump on this Thread, I'd like to know to, I'm in San antonio texas and it's hotter the h*ll here and my fan doesn't kick on till my gauge is a lil above the 3/4 mark right before it shows red. I'm sure i can search on how to do that trick with the fan you mentioned to bypass it but could you fill me in? This past saturday i put some DEI exhaust wrap on the headers in hope it helps keep heat away from the radiator (UGH WHY THE HELL DID HONDA PUT THE EXHAUST RIGHT BY THE RADIATOR?) Anyways i'll see if that has help today on the way home from work in the 100 degree weather. Is it one sensor that feeds the gauge and the fan kick on run off or is it two different sensors?


BTW Kinda new here so HI!

 

Bringing this thread back cause I cant find any answers. Anyone find out if its the thermo switch that causes this problem? My fan comes on once the bike is overheating as well which is about 3/4 on the gauge. Seems to me like it has to be the switch but if someone found another solution I dont wanna waste the money on one

 

The fan should come on right around the 2/3 to 3/4 mark on the temperature gauge, that is correct operation. If the coolant is boiling over at the same time as, or before, the fan kicks on the radiator cap is faulty and needs to be replaced. Faulty radiator caps, that allow the coolant to escape too soon, don't keep the system under enough pressure to effectively do its job. Pressurized coolant boils at a higher temperature than non-pressurized coolant.

 

Alrighty I guess mine is fine then, I just dont understand why it kicks in around 220ish instead of 195 or 200

 

its ok mine did the same thing, the radiator kicks in at about 2/3-3/4 like most f3's

but did bubble once wen it was been cold for a wile then hit a heat wave ( well i say heat wave lol i live in the uk so any thin about 20c is hot for us)

i took it to a Honda workshop and they put it dawn to the cap was damaged due to temperature ware and tear ( being frosty then hot in short space of time)

but the bike runs hot all the time its just one of her perks, she keeps my legs warm in the winter and makes me sweat in summer