over heated wire

[two-stroke-brit]

hi all this is the wire that runs from the top of the thermostate on my 73 buffalo,
it is getting real hot by the look of if .
what is causing this .
thanks mark

[stlrocker]

not too familiar with the 750 cooling system, but if thats the fan switch, the wiring diagram shows that as a brown wire that would switch the ground to pull in the coil on your fan relay. what could cause that is resistance from corrosion either in the wires or connections or wear on the contacts in the realy.

i would check resistance through the wire from end to end. and also check resistance and voltage through the relay. dont know if the relay can be opened up. if it can you may be able to check the contacts and see how they look.

either way replace the wire obviously, but it would help to know if it was the wire or the relay so it dosent happen again.

remember i am not familiar with these in person. this is just what i gather from my electrical knowledge and looking at the wiring diagram. it may be a place to start. someone with first hand experience with this may know of some common problem im not seeing.

[H2RICK]

Mark, your fan motor MAY be self-destructing and have a dead short across the armature. This would put a high amperage load on the whole circuit and the thinnest conductor would act as a "fuse" which is exactly what you're seeing......the wire is overheating and melting the insulation.
I would get my meter out and check the amperage on both sides of the motor while it's running. I have no exact idea what a small motor like that should draw but I'd be very surprised if it was more than ~0.75 amps. Maybe someone else who has run such a check on a known good fan motor can give an actual figure???
My .02 worth....

[two-stroke-brit]

Mark, your fan motor MAY be self-destructing and have a dead short across the armature. This would put a high amperage load on the whole circuit and the thinnest conductor would act as a "fuse" which is exactly what you're seeing......the wire is overheating and melting the insulation.
I would get my meter out and check the amperage on both sides of the motor while it's running. I have no exact idea what a small motor like that should draw but I'd be very surprised if it was more than ~0.75 amps. Maybe someone else who has run such a check on a known good fan motor can give an actual figure???
My .02 worth....

thanks for the advise but i am "special ed" when it comes to anything electrical .
i have a multi meter but need "an idiots guide to electricution" .
Also if i unplug the melting wire the fan runs constantly.
and the PO has replaced the fan in the past or had other issues because there are joins in the two wires leading to and from the fan.
where/what is the amature and where do i stick the meter probes to get the readings,
thanks mark

[jabcb]

Per Clymer, the fan should run constantly when you disconnect the brown wire.
Since this is happening, your fan motor looks to be OK.

SmokeRiders has the wiring diagram:
http://smokeriders.com/Technical/wiring ... grams.html
This isn't a direct link, it will take a few clicks to see the wiring diagram.

The fan motor relay's normal position is to provide power to the fan motor.
The engine thermoswitch shuts the fan off by grounding the brown wire, which is its connection to the fan motor relay. This trips the relay and shuts off the motor.

Looks like there might be a short in the fan motor relay. It might be still triping the relay to shut the fan off, but is passing way too much current to the brown wire.

My GT750 doesn't have a fan so I can't give you resistances or voltages to compare.

I didn't see the fan relays listed on eBay. Maybe somebody on the forum has a spare relay. Or you could get an alternative from an autoparts store.

[H2RICK]

If the relay IS bad then one of those 30 amp cube relays should do the job. IIRC, they can be used as either normally open or normally closed and they're worth about $10 at an auto parts store. 30 amps will be far more capacity than needed for that fan motor.
I wonder if the PO had a bad fan motor that overloaded the relay....but he never replaced the relay figuring that it was "good enough" ???

[two-stroke-brit]

If the relay IS bad then one of those 30 amp cube relays should do the job. IIRC, they can be used as either normally open or normally closed and they're worth about $10 at an auto parts store. 30 amps will be far more capacity than needed for that fan motor.
I wonder if the PO had a bad fan motor that overloaded the relay....but he never replaced the relay figuring that it was "good enough" ???

thanks rick that sounds like plan and your probaly right about the PO.
cheers mark