Hi All -

I've been having some cooling issues with my '02 F4i lately, and can't seem to get it fixed. The bike is running very hot, its usually around 200 F when I'm riding at 80mph on the freeway. It used to work well, around 185 on the freeway, but it seems like now I can't keep it under 200. The radiator looks good, holds water, no leaks, pressure tested. I also just replaced the thermostat (what a bitch!), and that didn't seem to solve the problem either. I did notice a bit of gunk in a ring around the bottom of the thermostat housing, could this be causing it to stay closed? Could the water pump not be working?
Also, my fan isn't kicking in until the bike reaches ~237 F or so... I'm guessing its the temperature sensor for the fan, but I want to make sure I'm looking at the correct part. On the online schematic, it looks like it goes on the left side of the radiator.

Please help, i want to start riding again! Thanks

 

hey mang...i had the same issue as you.
the pump is fine. you could have a blockage or an air bubble.
you need to clean your system out real good. do 50/50 mix distilled water and white (distilled) vinegar. The car flushing stuff is too strong for the seals, etc inside the cooling system.
so use the 50/50 mix for the flush. just put it in, let it run up past 180 and then drain it...or if you like, ride the bike around the block some more then drain.

this is the thing...bear with me...
the fan trigger switch is located on the left side of the radiator, furtherst away from the inflow. the temp sensor is located just beneath the t-stat, at the rear of the block. the trigger switch is supposed to complete the circuit somewhere around 220-228 degrees. so what's happening is that there's a big delay between the core area reaching 225 vs. when the temp sensor reads 225. this is most likely due to bad coolant, or obstructions/air bubble in the system located between the t-stat and radiator.

you check this you can run without your t-stat and watch, it'll take awhile to get to temp but once it reaches temps, the same thing will happen, so you'll know it's not your t-stast...

as for the water pump...if you take it apart, you'll see that it's directly connected to a shaft that turns with the tranny (i believe). so it's always turning! in order for it not to work, either that shaft has busted or the fan blades in the pump have busted off, both of which are HIGHLY unlikely unless you've crashed it.

also check to see if the temp spikes up and down...if it does...it could be an indication that there's air in they system or the coolant is boiling. also, check the rubber seal on your radiator cap...make sure it's still good...if it looks a bit worn, flip it over and reuse or get a new one.

Good luck!

 

I will give the vinegar a try - I'm waiting on a new rubber seal for the thermostat from the dealer... Stupid me, the manual says to be sure to install a new one, but I figure it'll be fine, put everything back together, and of course its leaking from the thermostat. Lesson learned, now that I have to do the whole thing over again.
Thanks for all the help. One more question - is ther any other coolant to use in our bikes? I always make a trip to the dealer to get the honda HP stuff, but I'd love to be able to go to my local parts store and grab something else. I just don't want anything that will eat away at my seals / has the wrong additives.

 

you can run Engine Ice, stuff racers use...50/50 mix...

or you can run distilled water and water wetter (only need like 3-4 capfuls).

 

Thanks for the help - put some vinegar in, let it run, flushed it out a few times w/ distilled H20, and its running great. Staying around 184 - 185 in the So Cal heat

 

well i am having similar problems where i got up to 231 on a hot day. but it was always fine untill i installl my exhaust and power commander. is it possible to just get air in the system even if it been fine for like 3500 miles?

 

Did it just get up to 231 once or twice? What's your normal temp on the freeway? Did the fan come on and bring down the temp?

These bikes run hot, and that's not so bad on a hot day if it comes back down. I wouldn't expect a new bike w/ 3500 mi to need coolant service.

 

fan always kicks on at 220..umm yeah it was once..but driving it seems to be around 185..but sometimes i'll look down and have been moving for awhile...and its at like 215..and im like wtf im not even beatiing on it

 

in hot weather, stuck at a light, it can get up to 230 plus...but don't worry unless when you're stuck in traffic the temp keeps rising even with the fan on.
steveo, your bike is fine.

 

My bike is running great, but the fan is still coming on around 235+ (I had to let it sit and idle for a good while to get it up to that temp). What part(s) exactly control at what temp. the fan comes on? It does kick in, but by the time it gets to 240, it has a hard time bringing temps back down.
I'm guessing I'll need a new one, but the terms fan switch and fan sensor get thrown around a lot.

Thermostat schematic
Over here on the thermostat page, there's part # 11 and #21 - I can't tell where either of them go physically on the bike, and 11 isn't even listed for purchase.

Radiator Schematic
over here on the radiator page, there's part #19 that's listed as thermostat switch...

Which one is gonna help me?

thanks
-Steve