Hi guys, i've try to find any posts about "how to check thermostat" but i can't find anything.

My 93 Honda F2 have an extra switch (you know "mexican tricks") and with this switch i can turn on the radiator fan, so i'm trying to find some post, or if anybody can help me to solve my problem, because i don't like turn on and off manually the fan.

my questions is, how can i check thermostat and fan switch are ok?, because if i take a ride on my cluster the temperature is always on "Cool".

thank you for your time!

Regards!!!

 

The systems you describe are actually two entirely separate systems.

1) The radiator fan is not connected to the instrument cluster in any way. In the bottom right hand corner of the radiator (when viewed from the front) there is a thermostat. The way this works is simple. When the water in the cooling system (flowing past the sensor) reaches boiling temperature, the switch makes continuity between the radiator chassis and the wire sticking out of the sensor. If you look closely, you'll notice that the radiator body is electrically insulated from the rest of the bike. Once the water boils, electricity can flow through the switch and into the fan, turning it on.

The test for this component is simple. Measure continuity using a multimeter between the threads of the thermostat and the brass connector on top. When cold, there should be no continuity. Next place the sensor in a pot of boiling water. After a few minutes the switch should become electrically continuous.

2) The sensor that's connected to your instrument cluster is another sensor, which I believe is located on the rear side of the cylinder head. There's a channel that flows coolant around the head and a black wire that attaches to the correct sensor. I would probably check that wire, or replace the sensor if you determine it's bad.

 

The sensor that feeds the needle on the instrument cluster is on the right rear of the cylinder head threaded into the top of the pocket the thermostat sits in. The thermostat and the sensor on the head are also in NO WAY related. The thermostat mechanically meters the flow of coolant from the engine head into the radiator, and the sensor (a brass doodad) simply feeds the instrument cluster the current temp. of the coolant in the engine head.

 

Also of note, while wrenching I advise that you don't bust off the sensor on the cylinder head that feeds the instrument cluster. It's a real doozey to get out if you do. You'll need a drill with lots of bits around 3/8" size, a pick, and a 1/8" NPT tap. It will take at least a half a day to fix if you do this, and you might need a new cylinder head if you don't play your cards right.

This is totally not the voice of experience speaking.

 

thank you very much.

i'm gonna do that, first check the fan switch and then the other sensor, but before please explain me this.

The F2 have 3 different parts to control temperature?
- fan switch
- temperature sensor
- thermostat

because i downloaded and read the service manual and show that 3 parts but the "thermostat" is just like a valve, isn't it?.

in case that the fan switch fail, anybody can tell the temperature range to get a new one.

 

If I were you, I'd just try to ServiceHonda or BikeBandit the fan switch if it is bad, instead of finding one of a similar temperature range and throwing something together.

The F2 and F3 share both thermostats (at least in physical dimensions) and temp gauge sensors. How do I know, you ask? I am using both and F3 Thermostat and an F3 sender in my '94 F2 at the moment.

And yes, the thermostat is just like a valve. It looks like a cartoon space ship. When it gets hot, it opens to allow coolant flow, and when it cools down it closes to bring motor temperature back up.

 

thank you amigo.

I do the test on the fan switch and the switch is dead, i need buy a new one, tomorrow i'm gonna check the temp sensor. Thanks for your time.

Please moderator, close this thread.

Regards!!