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Discussion Starter #1
I've long felt that the stock 100 deg C (switch on temp) of the stock cooling fan switch is unnecessarily high. And having a temerature gauge & a manual overide toggle switch has firmly convinced me of this.

It's only an issue in stop go, crawling traffic. But the stock switch allows the temperature to go quite a bit higher than normal & by the time it reaches the 100 deg C of the switch, the fan struggles to bring the temperature down - takes several minutes to start it dropping.

With a manual overide switch I noticed that if the fan is switched on earlier, the normal temperature is resumed much more quickly & holds very well.

After seeing a thread by N5XL on the T3 Sport Touring forum - which uses a different mounting size switch -

http://www.triumphrat.net/t3-sport-touring-forum/149905-cooling-fan-switch.html

I went looking for options for our classic triples. There's only a small number of standard mounting types - this one is a 20mm 'push fit'.

This is the one I found:

http://www.purems.com/products/product.php/II=2243

VW / Audi part # 021919369

which switches at 93 deg C....or 95 deg C for the item I actually bought from ebay in Germany:

http://cgi.ebay.de/Thermoschalter-blau-2-polig-VW-Bus-T4-Neu-/200507889840?pt=Autoteile_Zubeh%C3%B6r&hash=item2eaf3398b0

Same part number....there's obviously a small range of switching temperature that presumably meets VW/Audi's spec fpr this part.

Anyhow, it controls the temperature perfectly. After about 5 mins in a traffic jam, it picked up the rising temp earlier & quickly returned it to normal. Switching off almost as soon as I'd got rolling at a steady 30mph heading out of the traffic.

Fitting it.

The stock O-ring seal & clip works perfectly - I used the existing items, no problem.

I wasn't able to find out if the VW/Audi vehicles - one an 'S4' saloon, another a T4 Transporter (van) model - used the switch direct or via a relay. So I played safe and fitted one. Any standard or 'mini' type auto lighting relay will do. I fitted mine in the fairing cowl, but I'd be sure a 'mini' type would fit near the switch under the tank.

This switch is designed to take a common type (tho' didn't figure exactly which) of two-pin auto electrical plug, not the 1/4 spades of our looms. However I wasn't sure if a plug would be too long & foul the tank. So I soldered a couple of short wires to the pins with 1/4" male spade crimps to hook it up. Zip tying the wires to the body of the switch for strain relief.

If anyone has info - wiring diagram? - featuring this switch it would be handy to know if it can power the fan directly & reliably.

Not quite as slick a mod as N5XL's for the other T3s, but doable and worthwhile I think.
 

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Good find Mike.. I'm curious as to why you think a relay might be necessary when the stock fan does not use one? I take it the relay is switched by the fan switch?
 

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Where does this mount to the bike? Can you write up a brief installation How-to (or even just show the stock part that will be replaced in a photo) for those of us not familiar with the stock unit? I'd really like something like this that will kick on the fan at a lower temp - I've only had one or two times when I was worried (both on hot days in stop-and-go traffic just like you said), but it sounds like this would take care of that.

Thanks, man! :)
 

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Discussion Starter #4
Good find Mike.. I'm curious as to why you think a relay might be necessary when the stock fan does not use one? I take it the relay is switched by the fan switch?

Yep, the relay is switched by the fan switch. It's very likely the switch is capable of switching the fan's current load, but I couldn't find the info to confirm VW/Audi used it to directly switch a fan.

There's so much electronic control on modern vehicles & if the switch was to be used via a control box, possibly with some other conditions or timers, they may not have spec'd contacts up to the job of a direct connection. Or...they might also have chosen to keep loom wiring around the often longer engine bay runs to thinner sizes, typical of other sensor wiring - not suitable for the higher fan current & attendant significant volt drop on 12V circuits.

Add in that relays are dirt cheap & the fan switches are not (in Europe, I'd seen prices over €45 from VW franchised dealers), it seemed safer/more reliable to let a relay do the heavier current switching of the fan.

Hope this explains!
 

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Discussion Starter #5 (Edited)
Where does this mount to the bike? Can you write up a brief installation How-to (or even just show the stock part that will be replaced in a photo) for those of us not familiar with the stock unit? I'd really like something like this that will kick on the fan at a lower temp - I've only had one or two times when I was worried (both on hot days in stop-and-go traffic just like you said), but it sounds like this would take care of that.

Thanks, man! :)
I'm afraid I've not figured out being able to draw up neat custom wiring diagrams to put on the web. But this is a fairly simple job.

The fan switch faces out to the right & horizontally off the coolant filler/thermostat housing mounted on the top of the main frame tube under the tank. The switch is just to the rear of the coolant overflow/reservoir 'bottle'.

This is the type relay you want (bog standard, euro style 'micro' lighting relay):

Micro relays.
These are smaller than the standard relays
and have a different pin layout.
No brackets on these relays.
With diode protection for sensitive circuits. Pins 30 & 87 are 6.3mm
and pins 85, 86 & 87a
are 4.8mm blade.
Relay dimensions:
23x15x25mm (excluding pins).


Note the use of the smaller size, 4.8mm blade terminals!

The '4-blade' will do. I'd be sure it could be zip tied to the frame tube behind the thermostat housing & coolant overflow bottle with plenty of clearance for the fual tank to fit over.

The existing loom wires are unplugged & then connected to terminals 30 & 87 on the relay (either way round). Then, using a 'piggy back' crimp, connect a wire (smallest loom gauge is fine) from the terminal with the Blue/Black wire to one of the new fan switch terminals (by soldering).

(Note the Blue/Black wire is 12V positive all the time, even when the ignition switch is off - so disconnect the battery 1st before doing any wiring on this.)

The other fan switch terminal is then wired to one of the relay coil terminals - must be terminal #86 in this case as there's a diode connected internally.

Relay coil terminal # 85 is then wired to ground. A suitable option using a ring crimp is maybe an ignition coil mounting bolt or a thermostat housing mounting screw.

Reconnect the battery & bridge the new fan switch terminals together to test that the relay energises & fan starts running.

Tape up any exposed or potentially exposed parts of the connections & that's it.

I guess a photo of the area under the tank would be useful?, but, as I say, I fitted my relay under the fairing. (I left the toggle switch in circuit in mine because it has an LED in the toggle top which indicates both when the switch is on or fan relay is energised by the temperature switch.)

Anyhow, does this enable you to understand how to do it?
 

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Hope this explains!
Thanks Mike, that helps. I can see where you are coming from but I guess I just like to keep things simple. A relay is another link in the chain, so to speak.

I deffo like the idea of the lower temperature switch. 100c is cutting things a bit fine. Next stop, warped head
 

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Discussion Starter #7
Yep, definitely Slinky, simple is always desireable. I forgot to mention that whilst trying to find out about the switch's contact Amp ratings, I did come across some items which had low ratings - only intended to drive a relay or electronics. Just couldn't get the spec on this one & thus couldn't be certain about it. There was no other options with the right mounting diameter/type & temperature unfortunately.

That said, these relays have 25A contacts & are an incredibly reliable item generally.
 

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Discussion Starter #8
On a side note, I definitely think a water cooled engine needs some sort of temperature monitoring device as well. If a fan or fan switch fails on our bikes I agree a warped head or serious damage isn't far off.

I guess our bikes were designed a little before the widespread use of LCD/digital displays integrated into the clocks.

I doubt there's a modern (water cooled) bike on the market which doesn't have the coolant temperature prominently & continuously displayed & I doubt this is consumer driven - the manufacturers want it there for good reason.
 

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Good find/information Mike! I too agree that the fan comes on too late which is why I've installed a manual switch last week. I just have to remember to shut it off when the light turns green or the traffic starts moving.
 

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Just a thought.. what temperature does the thermostat open at? I'm just imaging a situation where the fan comes on before the thermostat opens, would that be a problem?
 

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Discussion Starter #11
Haynes lists the thermostat opening at 83degC, so we're well clear. (I'd be sure that's a reliable figure.)

My temp gauge also confirms that in normal running the fan will rarely kick in with a 93 to 95 deg switch. It's only the traffic lights / crawling speed situations.

In N5XL's write up for the T3 Sport/Touring models, he used a switch that came on at 92 C & off at 87 C with no problems.

He mentioned that the fan might run on a little longer when the ignition/engine is switched off, but in practice this isn't an issue. (He mentioned 2 to 3 minutes run on after engine off, but in Arizona temperatures!)

If anyone had concerns about battery drain, they could feed the fan switch (& hence relay coil) from an ingnition on +tive supply rather than pick up the always on +tive Blue/Black wire I've suggested above. This would then cut the fan off immediately the ignition is cut. But I strongly doubt this would be needed - the switches for ours switch at 1 to 3 deg higher in any case than N5XL's switch.

(Actually mine is wired this way, but only because I retained the manual switch I'd fitted & don't want it capable of switching the fan on by someone fiddling while it's parked.)
 

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I ordered one.

I'm guessing it's just a mechanical bi-metalic switch so I didn't use a relay. I also found some small insulated connectors that fit. They don't stick out as far as the coolant tank, so I don't think they will rub on the gas tank.

The switch appears to work well. On 90F+ days in traffic here, the fan has been on when I stoped and turned off the engine. The temp light hadn't come on. The fan shut off shortly after I shut down the engine.

Hurray!!!

Thanks Much:D
 

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Just reviving this thread if possible. The temperature of the 96 thunderbird in these hot Sydney days was causing a concern so I thought why not fit the VW part and see if it works as described in the thread. So I ordered the part today.
Now in the thread there was mention of a relay and another where it was decided that it was not required. How is it working out? Is the switch reliable without the relay?
Or is it better to fit the relay?
On a similar note I noticed that there was some coolant staining on the left hand case of the bike coming from the radiator somewhere near the top radiator hose. I tightened the hose up but there is still some drips occasionally. A tiny amount only. Do you pressure test the system? How is it done?

Brian
 

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I installed the VW switch in May. I didn't add a relay.

It's still working well - haven't had any problems. On hot days or when I've been in traffic, I'll hear the fan running when I shut off the engine. I don't see the light much anymore.
 

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I fitted the switch and a relay to the system today, as in my investigation, I found some wiring diagrams for VW Urban Camper Van of 1993 vintage and they use the part. All fed into a relay before the fan.
As an extra it would be best to fit a new rubber O-ring to the switch part Number 90316802 according to my receipt. $3.00 is cheap insurance and it fits exactly
There is a nice space for the relay right under the switch above the coils. I stuck the relay down with double sided tape and a zip tie. You can use some female blade terminals 1/8” inch to fit the wire to the switch.
After about 10mins of idle the fan kicked in and switched off a little later.
I now have a Cool Triumph Thunderbird!
(Sorry about that)
Thanks to IrlMike and N5XL for all the information it made the process easy.
I added some photographs of the installation on the Albums section.
Brian
 

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So, I've been exploring this issue for my Tbird - my friend is a VW mechanic, had some old VW's around, found a switch that fits, but when I heated it up to test it, the fan ran at a lower speed than with the original. It did this with 2 different switches I tested. You who have done this - are you sure the fan runs at full speed? It may be that there are too many different types and I need to just go buy the exact one you specified, IrlMike, but thought I'd ask for sure.... thanks!
 
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