Hey guys,

I need to replace the thermo switch on my '87 CBR1000F. This is the switch that is installed into the corner of the radiator and grounds the fan connection when it hits the right temperature. The Honda part # is 37760-MT2-003.

Does anyone know if there is an aftermarket replacement available from Autozone/NAPA/Carquest? I think there's an alternative that fits into a Honda accord but I don't know this for sure.

Thanks in advance for the help,

Rabid

 

Maybe try this to save a few bucks- http://cgi.ebay.com/ebaymotors/Honda...21210010r15738

Why do you think you need it anyway?

 

You could fit a bypass switch and run the fan that way too.
There was a fan thermo switch on e-Bay that came in at lower temp than standard, to improve cooling.

 

Thanks guys.

I already have the manual toggle switch to turn it on/off. I was hoping I could find an OEM alternative from an auto parts store to save on the cost of the thermo switch.

Shadow - I heard that you have to replace the thermostat with a lower temperature model if you go with that lower temp thermo sensor, otherwise the fan will run forever. Do you know if that's true?

 

Rabid, the two items, the thermo-switch and the thermostat have similar functions, but aren't tied together. The thermostat only determines when to allow water to circulate through the engine. When the engine water temperature goes above the temp of the thermostat, it opens. The thermo-switch determines when to turn on the radiator fan based on the water temperature in the radiator. If the water temp is higher than the temperature of the thermo-switch, then it turns on.

 

Thanks idodirt. Great explanation. Do you know if I can test the thermo-switch somehow? I want to make sure it is indeed broken before ordering a new one. I'm wondering if it's possible that the wiring is messed up.

 

If the fan comes on cuts off then your switch should be working ok. My fan doesn't come on until the temp guage gets to about 3/4 up in the operating range. Also, make sure you've got enough coolant. Too little will cause overheating.

 

Thanks joe. I flushed my coolant and replaced 3 of the 6 coolant hoses. My fan does not come on at all, I just have the manual override toggle switch but I'd rather have the thermo switch working so I don't have to worry about it.

 

I haven't seen any specifications on the temperature at which the Thermo-Switch closes. I would think it would be a simple test. Here's my thinking. First off, this device is just a switch. That means that it doesn't use any power, it just allows electricity to pass through it or it blocks it. Like putting two wires together or taking them apart. So, with that in mind, here's the test. Take it off the bike and with a meter set on Ohms, connect one lead (it doesn't matter which one) to the terminal that the wire attaches to, and the other lead attached to the metal housing or threads of the Thermo_Switch. Put it in a pan of water. To start out, the meter should be reading infinite resistance. Heat the water on the stove until it boils. At some point before it boils, the meter should drop rather suddenly to near 0 (zero) Ohms. If it doesn't, then it's bad.

Hope this helps.

 

As I recall, the fan opening is at around 87C. It's in the manual somewhere but I don't have time to search for it ATM. Sorry.