Fans

[Ant132]

Hi all,

I was cleaning my Trident today and rubbing my cloth over the small metal panel just under the clocks i heard a noise, i investigate and find a small 'button' i press the button and it operates the fan. Only found that out today

Anyway, what im wondering is, as ive never heard the fan cut in by itself, will this custom fan switch mean that my bike doesnt know when to tell the fan to work now? Is it down to me to decide when to turn the fan on, or is it both?

I have noticed the bike getting hotter more recently due to traffic/congested journeys and the weather warming up. And the temp gauge sometimes strays over half way, so, when approx. does the fan come on?

Thanks for any help, Ant

[KitNYC]

This button sounds a bit dodgy. Someone whose opinions I respect, I forget who, recently posted that he had installed a supplemental fan switch that allowed the fan to be turned on manually as well as automatically. While I don't think it's necessary, I do understand the logic and feel that that's not a bad mod. Usually, though, when you find a fan switch unexpectedly, it means the thermostat broke and some bumbling oaf has bodged a lamp switch onto the wire instead of fixing the actual problem.

IIRC, the fan usually came on on my Trident somewhere between 2/3 and 3/4 of the way across the heat gauge, i.e. almost never for most of the time I had it, but alarmingly often when the head gasket was on the way out.

The thermostat and the gauge are not driven by the same sensor, BTW.

Cheers, HTH,
-Kit

[IrlMike]

Possibly me who fitted a manual fan switch, Kit?

I fitted it as an overide, so the stock fan switch will (should!) still operate if the coolant reaches the set temperature. My bike's a Legend TT (885 T3 motor, lower tuned) - or started out as one anyway . I fitted Trophy/Trident clocks a while back after the original Tacho had it's own ideas about engine revs, & hooked up the temp gauge as well. I noticed then that in all riding conditions/speeds except really slow stop/go conditions the temperature stayed nice & low, beteen 1/4 & 1/3 up the gauge. But in city stop/go situations, the temp rises rapidly, 3/4 or a tad more up the gauge, & the engine clearly didn't like it. It also tended to spit out some coolant too. Likely the oil temp is going up quite a bit too. Not great.

IMO the fan switch temp is set too high & by the time the fan does come on, the fan struggles to bring the temp back down. After the head gasket let go on my buddy's Tbird Sport last year, I heard a number of comments, incl. one from Sandy at Triumphant who specialises in rebuilding T3s (among lots of other Triumph goodness), that head gaskets/head warping can be a weak area on these engines - not big nos of failures, but some. Seems to me that elevated temps, perhaps a little coolant loss that goes unnoticed, could well be a contributory factor. The switching set point of the fan switch could 'drift' as well, how would we notice? Overall, the issue may be minor in how often it becomes a serious problem, but for me, I see it as cheap insurance.

When the temp is spotted rising a little & I may be stuck in traffic a while , I switch the fan on & it has no difficulty in keeping the temp normal. Handy for a carb balance/tuning session too, to maintain engine temp around normal.

It sounds like a PO did this mod on your (OP's) Trident? If they did, it's most likely that they just paralleled onto the existing fan switch connections. No reason not to, & it's a convenient point to wire into. Shouldn't be too hard to follow the wiring back & see. They possibly used a relay, as I did, with the switch/relay coil + feed taken from an 'ignition +' line. That way the relay drops out when the ignition is switched off.

If the mod looks like this & done properly, I'd keep it .

[KitNYC]

I think it was you I was thinking of, Mike, and given your (and Sandy's) comments and the fate of my Trident I'm starting to agree that the manual switch in parallel is a good idea...

Cheers,
-Kit

[sailfish]

You can wire the manual switch by simply jumping across the two terminals of the stock Triumph switch with the manual switch inline of the "jumper". No additional relay needed. You'd just have to remember to turn it off before walking away from the bike.