ST1100 Fan not kicking in,

Hi yesterday on a long road trip I got to some traffic in rush hour, The temp just sawed up over the top! Soon as riding It came normal again. Today I have just completed a 90mile trip no issues, until I reached town and was stuck in road works, then back hot again.

I got back home and left it ticking over, and can clearly hear the fan is not kicking in. Where do I start to look at for this?
Cheers

Stu

common issue, lots of threads here on the topic.

first step, verify the radiator is full by removing the bodywork and removing the radiator cap. If its not full, fill it. While there check for a split in the small diameter hose that runs from the rad cap area to the recovery bottle and repair it if necessary.

If radiator was low on coolant, test again by riding bike after filling radiator.

If radiator level and hose checked out OK, and fan still not operating, next remove the connector from the temp switch in the radiator and ground it to the engine or frame with the key on. If the fan comes on then your fan circuit is OK, and your thermal switch has likely failed. If the fan doesn't come on, then check fuses and connectors in the electrical path from the battery to the fan.

Check fuse first. if fuse is good, disconnect fan, and hot wire it. Blown fuse, replace, and proceed with testing. No run, fan no good. If runs, bypass temp sender for fan, if runs, sender is bad. That's a pretty basic start point. Other problems can include a bad connector, or broken wire, but, mostly I've seen either a bad sender or fan.

Ozzie said:

...mostly I've seen either a bad sender or fan.

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Check coolant level and fan/stat operation first...
However, since its a UK bike, given possibilities that the ground wire has corroded off the fan motor bracket...

Cheers, it's well maintained and serviced by prev owner. Water pump was replaced at last service, going book in for major service and ask them to check. On a side note, how would I know if valve clearances need doing?


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StuartKeith said:

how would I know if valve clearances need doing?

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If you hear a constant tapping noise that increases with RPM, (loose valves), coming from the top of the engine, you likely need a valve adjustment. However, valves that have become too tight will not make any noise and could lead to burned valves without warning. The 1100 valve train has proven very reliable and rock steady at maintaining proper clearances over thousands of miles, so if the PO had them done, they are probably OK.

StuartKeith said:

Snip, snip .... Water pump was replaced at last service, going book in for major service and ask them to check.

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Make sure they attached the ground strap to the fan assembly/radiator.

Cheers, I take it, this is the part I may need? garage quoted me ?60 for it. I may order it just to get them to fit it in the service.

http://www.ebay.co.uk/itm/TourMax-Thermostat-Fan-Switch-fits-Honda-ST-1100-Pan-European-1990-2001-/141719934510?hash=item20ff2a962e:g:J3oAAOSw3ydVpyAY

And this too?

http://www.ebay.co.uk/itm/TourMax-Water-Coolant-Temperature-Sensor-fits-Honda-ST1100-PanEuropean-1990-2001-/131658052170?hash=item1ea76e724a:g:jfgAAOSwgyxWUP1k

I doubt that the temp-probe is gone, but the "Klixon" from the first link might be a cure for the issue.

OK, I grounded the fan to eath, and it didnt kick in, so either fuse, or power related it seems. WIll look into it the weekend when can get te tupperware off.

It may be as simple as the wire wasn't connected back on the fan switch when they replaced the water pump. Take off the left hand plastic ( clutch lever side ) first to check that. I assumed at first they wouldn't have overlooked that

Jim Van said:

It may be as simple as the wire wasn't connected back on the fan switch when they replaced the water pump. Take off the left hand plastic ( clutch lever side ) first to check that. I assumed at first they wouldn't have overlooked that

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I assumed when he said "grounded the fan" he was referring to using that wire.

OP: if that isn't what you did then hunt around for that wire and make sure its connected properly on both ends, since you'll need to do that anyway.

dwalby said:

I assumed when he said "grounded the fan" he was referring to using that wire.

OP: if that isn't what you did then hunt around for that wire and make sure its connected properly on both ends, since you'll need to do that anyway.

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Nope, that's what I did. Little booted wire on the sensor switch. I didn't remove the plastic, just used another wire poked in as tried after work and was getting dark. Am away this weekend so will try next weekend

Well I finally managed to get her stripped down a bit today to fit the heated grips (Which I found out the controller needs replacing!) I noticed as soon as I took the grey left panel off a big wiring block hanging down with nothing connected. Digging my hands in, I maned to find the other half of the harnes and connect it up. Shorted the fan to earth, and low and behold, the fan kicks in!. So thats sorted. So to do,

Fit new Diaphram for clutch and blead/replace fluid as gear change crud and fluids like mud (Have part, will get them to do on service)
Replace fork seals, as left side blew on thursday (Again have parts will get to fit on service)
Replace Oxford heated grip controller
Replace rear shock (Do next month before mot)

Bike is going in for an interrim service on Thursday so should be good for the summer. Rear shock is looking a little weepy, and bottoms out over spead bumps. Hopefully it will stay dry enough for MOT other wise thats going to get expenisve this month also.