Electric fan / radiator

[TR Rob]

My TR3a has an electric fan which is operated manually via a switch on the dashboard. It relies on me keeping a watchful eye on the temperature gauge …. while this adds to the TR experience , I find it a bit hit and miss especially when road conditions get a bit hazardous.

I was thinking of adding a sensor to one of the radiator hoses, my question is what temperature is “Normal” and what is the internal diameter of the radiator hoses. 
 

Also would you fit a sensor that kicks in a few degrees below normal, to allow for reaction time etc.

Thanks

[RobH]

Normal on mine is just a bit shy of 185ºF on the dial.  The best way to add a thermo switch is to use one of the lower return pipes which has a boss to take one.  (item 29 and 29a here).  

https://www.moss-europe.co.uk/shop-by-model/triumph/tr2-4a/cooling-system/cooling-fan-fittings/water-pump-fan-fittings-tr2-4a-1953-67.html

There are four switch options there.  Bearing in mind that is the water return pipe where the water should be cooler,  86ºC on/ 76ºC off would be my choice. 

 

Edited September 8, 2023 by RobH

[BlueTR3A-5EKT]

This in the bottom hose adaptor with adjustable temperature sender switch is whet I have fitted.   Fiddly to get at to set up but once on and working it has been reliable for 10 years plus now.   Had to reduce the length of the steel lip between the hoses to get it in.   The adjuster screw is visible through the LH wheel arc with wheel off.

https://revotec.com/product-category/electronic-fan-controllers/hose-fitting-efc/

 

Edited September 8, 2023 by BlueTR3A-5EKT

[Lebro]

Well, I bought a Revotech fan which came with the above adjustable thermostat. It failed on me twice (1st time It recovered after disconnecting & re-connecting some time later, 2nd time it was terminal)

I now use a stainless joining pipe with a threaded boss to take a mechanical thermostat (Otter switch) in the bottom hose.

No problems since. (I do also have an override switch)

Bob

[Hamish]

19 hours ago, RobH said:The best way to add a thermo switch is to use one of the lower return pipes which has a boss to take one.  (item 29 and 29a here).  

https://www.moss-europe.co.uk/shop-by-model/triumph/tr2-4a/cooling-system/cooling-fan-fittings/water-pump-fan-fittings-tr2-4a-1953-67.html

 

 

This is the same system as mine - my normal range is 185 to 207f (the next mark on the gauge) this is the window that the on off switch works. 
with a manual override

 

[Andy Moltu]

If it’s in the top hose the temp should be about 4 degrees Celsius above the water thermostat temp. (Not sure what the bottom hose ones are)

My experience with Revotec switches are similar to Bob’s. Not long lived.

I know Kenlowe are out of the classic game but you can get a generic Adjustable capilliary one and set it to your choice of temp by the gauge. I know some complain that it’s hard to seal in the hose but a groove scored into a bit of inner tube rubber worked for me.

[james christie]

I have a very old Kenlowe pusher fan whichwas supplied with a foam insert with a groove for the sensor fitted in the top hose.

After persistent leaks I went over to the Otter switch in the SS pipe, which will be used when I get around to fitting my Revotec

The Kenlowe override switch is something very complicated. If anybody needs a circuit diagram from Kenlowe, I have it somewhere

james

[John McCormack]

I use a manual switch. I have had too many of our members miss the temperature rise and the auto fan hasn't come on. There is a real risk of major damage.

However, a much bigger problem awaits those who use waterless coolant. We've had two cars destroy the engine because they missed the temperature rise and there was no steam to warn them.

I once flew for a living so have a very good instrument scan. It is really necessary that we all develop a good scan irrespective of using an auto or manual switch.

[TimG]

I have an electric fan with auto switch in bottom of rad. It failed once when backing into garage, its fed off the 35A fuse for the horns & it had blown. I'd like to fit an override switch I suppose fed from an ignition switch supplied feed somewhere that will take a big load or from a new relay. There is a relay for the fan behind RH headlamp, would I splice into the feed from there to the fan?

[RobH]

It takes a lot to blow a 35A fuse.  It might just have failed due to age but it would be well worth checking the circuit just in case there is a short somewhere.  There will be a large current spike as the fan starts up. If the fan is stalled or slow to start for any reason the current will be high until it gets going. 

If the fan already has a relay it would be easiest to fit a manual switch to operate the relay.  Wire it in parallel with the thermal sensor if that is a simple thing.  Not so easy if the relay unit is one of the adjustable temperature type though. 

(Do you have a diagram of how the fan is wired? )

 

 

Edited September 10, 2023 by RobH

[TimG]

Rob this is the installation, yellow 12v supply, blu& brown heading down to the fan, Blu& Br heading left to sensor. There does not seem to be any adjustment to cut in setting.

Edited September 10, 2023 by TimG

[RobH]

Nice and simple. It looks to me as if you can connect a manual switch from ( I think) 86 on the relay, the blue wire, to earth and that will operate the relay.  

Edited September 10, 2023 by RobH

[TimG]

Rob are you saying take a supply from yellow on the relay via a manual switch & then splice into the blue wire from sensor? I'd rather take a feed from elsewhere than the horn fuse the if it fails I can manually switch the fan.

[RobH]

No Tim the yellow wire is supply. The switch needs to go from the blue wire to earth ,  so it does the same thing as the thermal switch.  Unfortunately yours seems to have two blue wires so be careful which one you connect to. 

I think this is how yours is wired. The relay pins have been used oddly but that doesn't matter in this case. This is the conventional method of doing things to addd a manual switch. 

 

Yes you could connect a manual switch from a 12v feed to the blue wire on pin 30 pin. That will also work but means the switch is taking the high current rather than the relay.    As I said before if the fuse is blowing there is possibly something wrong. It would be safer to sort that problem than to fit a switch which merely bypasses it.  Better not to have a fire than not to have a fan I think. 

Edited September 10, 2023 by RobH

[TimG]

Thanks Rob got it, blue wire from sensor on 86 to earth via a new switch. Easy to test with a short wire from blue sensor wire to earth. Its my only car at moment so I dont want to do anything with a chance to disable it.

[TimG]

I'm looking for a suitable switch ideally latching push one but what load does it need to take for the fan? I think the old blown fuse was just very old it fell apart on removal

Edited September 16, 2023 by TimG

[RobH]

If it's just operating the fan relay almost any switch will do - the current is less than 1A

If you are wiring the switch to take the whole fan motor current though it needs to be rated for 30A, because on start-up fans take a lot of current initially. 

[TimG]

I found this switch but its only good for 2A  https://www.carbuilder.com/uk/chrome-latching-push-button-switch but in parallel with thermal switch should be OK.

Edited September 16, 2023 by TimG

[RobH]

Fine if it is just switching the relay current. 

[Moliver]

Hello All, 

I  have an electric fan as well, however (as I have found out recently) a fix thermoswitch,  which the preowner has installed on the bottom of the radiator (welded in boss).

The normal operating temp on mine as well is 185 F (85C). It increases to 207 (97) when stop and go or steep climbing. The fan kicks in at 207 (97C) gage reading, which I think is a tick too late. I am not sure about the termoswitch installed, however based on the obsetvations, I  guess it must be a 90/95C. I will  replace this  by a 82/87 C which I have just ordered.

The interesting fakt (and root cause for my investigations ) is, that I have coolant blow-off at the point where the fan kicks in (207/97) . With a 4 lbs cap, this should not happen below 224 F (107C),  which I do not reach at all.

So I suspect a defect cap and will repalce this as well. I hope these measures will allow to manage temps even in summer and mountain explorations. 

An adjustable thermoswitch would be very nice and would even be able  from Revotech to replace my radiator installed switch. It is just quite expensive in Germany and I only will opt for it if none of the two fix switch ranges will be suitable.

Cheers

Oliver

 

[RobH]

16 minutes ago, Moliver said:

The interesting fakt (and root cause for my investigations ) is, that I have coolant blow-off at the point where the fan kicks in (207/97)

There was recently some discussion about radiator caps which were just a tad too short to seal properly - might it be that? .  Also if you overfill the radiator you will get water blown out anyway as it expands.  You only need a cm or less of water visible in the bottom of the neck when cold. 

[Moliver]

Hello Rob, 

Yes, I am quite sure that the cap has a defect. Can U send the link to the above mentioned discussion ?

Tks

Oliver

[Z320]

Hi Oliver,

I Rob I suppose you don't have enough air in the system to be compressed.

Don't worry the air, the pump is strong enough to keep the air in the flow.

I rememer the rad cap post, but as this forum has "no" structure like "steering", "electric", "cooling" I can't find it.

Do you still use the bellows thermostat?

Tschüss, Marco

[RobH]

This one 

 

Edited September 17, 2023 by RobH

[Moliver]

Thanks a lot.

I did have a 20 mm version installed and the 26 mm version should be the correct one. Easy to fix but good to know. May still exchange the temp swith as it may allow to operate continously around 185.

 made a brief sketch which may help for reference for further posts...