Thermo switch for electric fan

[Ralph Whitaker]

Just getting ready to order rad hoses etc for the car, and thinking of buying the stainless bottom section that Moss does that accepts a thermostatic switch for the electric fan, and a switch to suit, but there is a choice of 4

PIPE, water return, stainless steel

Notes: With adaptor for Kenlowe electric fan thermo' switch

130039SST

£26.60

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THERMO’ SWITCH, (86°C on - 76°C off)

IM50250

£7.50

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THERMO’ SWITCH, (86°C on - 81°C off)

IM50090

£10.00

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THERMO’ SWITCH, (82°C on - 68°C off)

IM50100

£8.60

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THERMO’ SWITCH, (88°C on - 79°C off)

IM50120

£8.60

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The engine is a standard TR4 unit, no mods, and the radiator has been re-cored without the starter hole, which of the above switches do you all think would be most suitable?

Thanks, Ralph.

[BlueTR3A-5EKT]

Manners has the pipe you want and claims it is in stock.   https://www.abingdonmgparts.co.uk/product/pipe-with-adaptor%3a--tr2%2c-tr3%2c-tr4a/130039sst

I use a Revotec adjustable thermo switch so sorry can't help with the ideal temp switch.  https://revotec.com/acatalog/Negative-Earth-Electronic-Fan-Controller.html

Cheers

Peter W

 

[Ian Vincent]

I have the stainless pipe with the switch insert.  The switch I use is 88 deg C on and 79 deg C off.  It works well, the fan comes on when the temperature gauge goes a few mm past the mid point on the gauge and switches off when the temp drops to just above midpoint.

Beware however that it is tricky getting the hoses to seal onto the very slippery stainless pipe which is slightly smaller in diameter than the original (at least mine was).  I had to use wellseal under the hoses.

Rgds Ian

[Ralph Whitaker]

Just tried to buy the pipe from Manners. Went through registration procedure, tried to log in to but and not recognised. Also cannot find an on line section for TR, just a list of page after page of part numbers with no prices. They need to take some lessons from Moss and Rimmers I think.

[trchris]

Have you tried TRGB?

Chris

[Ian Vincent]

TRGB have them.

https://www.trgb.co.uk/collections/radiators-and-cooling

Rgds Ian

[Ralph Whitaker]

Thanks Ian, I never think of these "other suppliers", perhaps because I have the Moss and Rimmers books in front of me and its easy to flick through and find what you want. I have just ordered several parts from TRGB including the pipe I wanted, I found their prices to be reasonable and the site easy to use.

Ralph.

[Drewmotty]

I now use 88°C on - 79°C off the same as Ian after having two Revotec adjustable switches fail on me over a 5 year period.

[Hamish]

I have the same 88-79 to operate fan. Seems to work ok for me. 
 

This takes my temp gauge to the next marker 207F (97c) after the mid point 185F.
 

so a discrepancy between gauge and actual temp.

 

[RobH]

 Remember that in the bottom pipe the switch is measuring the cooled return water from the rad so the top of the engine will be hotter.  As a rule of thumb a 10 degree drop across the radiator is normal so if the return water is tripping the switch at 88 degrees, the water at the rad inlet will be about 98 degrees - maybe your gauge isn't far out after all.

 

[Hamish]

33 minutes ago, RobH said:

 Remember that in the bottom pipe the switch is measuring the cooled return water from the rad so the top of the engine will be hotter.  As a rule of thumb a 10 degree drop across the radiator is normal so if the return water is tripping the switch at 88 degrees, the water at the rad inlet will be about 98 degrees - maybe your gauge isn't far out after all.

 

Thanks Rob

didnt think of the relative positions. 

[Lebro]

Well, I am using a 92° / 87° thermoswitch in the steel part of the bottom hose. have done for the past 6 years (after my Revotech one failed)

It switches on when the needle is at around 194°, & goes off at around 185° that's if I have not already overridden it, (which I usually have)

Quite happy with those temperatures. Normal running (with 88° shielded thermostat) is 183-186 °

I did calibrate my capillary gauge prior to fitting, so happy about it's accuracy.

Bob.

[Ralph Whitaker]

Think I will go with the 88on 79off then as three of you have been using that happily. 

Bob mentions the shielded thermostat, as I understand it this is designed to shut off the by pass when temperature is reached, forcing all the water to go through the radiator. I see they are available (at a considerable cost), but  that also listed are the later non shielded types.

As a non shielded does not stop water "short cutting" the rad does this have an adverse effect, ie lead to hotter running, or as they are sold as suitable do they have little or no effect.  Thoughts please.

Thanks, Ralph.

[Ian Vincent]

If you fit a non shielded thermostat you need to restrict the bypass. I use a suitable coin with a 6mm hole drilled in it and held in place against the outlet by a second jubilee clip on the bypass hose. 

Rgds Ian

[Hamish]

I ended up with a 22mm copper blank with an off set hole. The pipe holds it in place nicely.

[Lebro]

Why offset ?

Bob.

[Hamish]

3 hours ago, Lebro said:

Why offset ?

Bob.

I thought that any air in the system would be at the top that’s all. 
 

 

[BlueTR3A-5EKT]

Have you fitted a vent valve in the top of the thermo housing also?

Peter W

[Hamish]

54 minutes ago, BlueTR3A-5EKT said:

Have you fitted a vent valve in the top of the thermo housing also?

Peter W

No Peter not done that. 
not had bleed problems but I do have a sealed system with expansion tank.

[Ralph Whitaker]

Glad I asked or would not have known to restrict the by pass. Sorted.

Thanks.

[BlueTR3A-5EKT]

1/8" BSP bleed screw in thermo housing on TR3A

 

[Ralph Whitaker]

As the heater sits high up is this a problem to bleed the air out of.

Ralph

[Rodbr]

I have found these to be very good in the past.

http://www.leacyclassics.com/catalogsearch/result/?q=+water+pipe&cat=1388

Rod

[John McCormack]

I prefer a manual switch under the dash. On the TR6 I have the engine fan and a electric fan in front of the radiator, the electric one is very rarely needed.

On a TR2 I have only the electric fan. I prefer being able to turn it on or off at will rather than relying on a switch that may fail. Having a manual switch I find I stay attuned to what is going on and maintain a good scan of the instruments.

[Lebro]

Both must be better, I use a manual switch whenever I think I will be in slow traffic for more than a few minutes, but, If I forget, then it happens automaticaly as the temperature rises above normal.

Bob.