Classic cars forum & vehicle restoration.

[Ray White]

Just had an idea and thought I would ask the forum for their opinions.

The MG TC did not have a temperature gauge of any kind so I am installing one.

However, as I am installing an electric fan it occurred to me that should it fail or the fuse blow - and I didn't notice the temperature gauge - the engine could suffer serious over heating damage before I realised it.

I thought perhaps I could wire the fan into the ignition circuit so if the fan stopped working the engine would also stop - thus drawing my attention to the problem.

Is it a silly idea?

1) On a hot day, an electric fan would normally continue to run when the ignition was switched off until it cooled.

2) On a cold day the fan is not needed much anyway so a blown fan fuse may be the last thing to suspect.

[Rick]

Maybe have an audible buzzer, but I wouldn't want the car deciding to switch the engine off for me

RJ
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[ukdave2002]

Wiring through ignition fuse makes sense, of course if the fan simply stops working there wont be any warning other than a rise in temperature.

One of the reasons my dad always fitted an ammeter to his cars was that if the fan belt started to slip you would see a lower than normal charge that may not light the ignition warning lamp.

Dave

[Ray White]

Interesting. Rick and Dave you make the points that were worrying me.

Unfortunately, I know what I am like; I have become complacent and forgetful. The chances are I won't be looking at the gauges when a problem occurs.


I could fit a buzzer to warn me if the fan fails - but when I had one on the Dodge indicators it failed twice.!

Perhaps I am being over cautious as usual?.

[peter scott]

[Peter_L]

The engine could overheat for several reasons, personally I wouldn't put the fuse into the ignition coil circuit. A temperature warning device would be useful. Isn't checking one's instruments part of the whole driving scenario along with ("mechanical awareness" as per Peter S )

[Ray White]

[quote="Peter_L".... Isn't checking one's instruments part of the whole driving scenario along with ("mechanical awareness" as per Peter S )[/quote]

MG did not fit a temperature warning devise of any kind. Not even a radiator mounted type as found on pre War cars. Presumably they had sufficient confidence in the rather sophisticated thermostatically controlled system which kept the temperature at 74 degrees. That said, experiences of other T type users is the propensity of the XPAG to overheat hence I am fitting a water temperature gauge. Whether I can be relied on to keep looking at it is a moot point.

On reflection I think it would be safer for me to have at least a chance of getting the car parked up safely; rather than be marooned in a dangerous location.

I will therefore give the fan its own fuse. The fan is 80 watts so what size fuse should it have? 15A?

[Peter_L]

Amps multiplied by Volts equals Watts

Watts divided by Volts equals Amps

1000W / 250 V = 4A 1000W/110 V = 9A

4 Amp Load at 250 V = 1000W 4 Amp Load at 12 V = 48W

15 Amp Load at 250 V = 3750 W 15 Amp Load at 12V = 180W

[Ray White]

Another development regarding the question of which fuse to use. I have re read the fitting instructions for the electric fan and it says there needs to be an ignition sourced supply. As the ignition is fused I think that must be the answer.

I can't remember how the Kenlowe fan was wired on the GT6 but I do remember how it continued to run after the engine/ignition had been switched off on a hot day. Presumably it was on a separate circuit?