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MG Midget and Sprite Technical - Kenlowe fan thermostat

Hi, what temp should I set the thermostat to cut in? Car is 1275 standard spec, engine thermostat is 88 degrees I think.
Thanks,
Andrew
aj robinson

Andrew,
usually the water thermostat fitted in this country is 82c or perhaps 88c if you change it for winter use

assuming your Kenlowe probe is tucked under the top hose I think I'd start at around 92c (200f) on the Kenlowe dial and see how it goes from there - but 1275 owners with a Kenlowe fitted will know better
Nigel Atkins

Thanks Nigel. Think I will double check the engine thermostat. I remember changing it a few years ago but can't remember why/ if I changed it to an 88 degrees one.
aj robinson

Andrew,
on the open road, when the engine has fully warmed up and subject to your cooling/heating system being in good condition, then on a 1275 with an 82c stat your temp gauge needle might be around well before the 'N' (say around 160f/71c)

an 88c stat might be just before the 'N' (say around 170f/77c)

Nigel Atkins

Thanks for the photo Nigel. Now my C - N - H temp gauge makes some sense!

Colin
Colin Mee

Colin,
the CHN I think is better as it's less confusing about temperature figures as the gauge is only measuring at one point and on our cars the needle can flicker and move up or down quite quickly

having figures is fine for reference as long as you don't get fixated on the numbers too much

Nigel Atkins

Type of engine thermostat fitted is irrelevant to the setting of the fan thermostat. I find adjusting the dial - with the thermo-couple fitted under the top hose - so fan cuts in at just above N on the temp gauge works well. Tends to only cut in if idling and stationary for longer than a few minutes - a little less if warmer weather. Never cuts in when car is moving and if it does, it means the cooling system/rad requires attention. Do not try to frig this by turning the fan dial!

Mark O

Thanks everyone. As always, very sound advice.
Regards,
Andrew
aj robinson

actually Mark the stat temperature does make a difference to where you set the thermoswitch otherwise with the temperature ranges of the water stat opening and closing and the thermoswitch cutting in and out you could have an overlap causing cycling of fan and possibly stat
Nigel Atkins

When I first got mine, I followed the instructions to set the dial. It said to set it higher to allow your engine to run at a "more efficient"(their words) slightly higher temperature.
After watching the needle on my temp gauge climb nerve wrackingly higher on a few occasions, the head gasket blew.
So I set it at just above N on the dial and have had no trouble since.
Like Mark's car it cuts in about 9Of, climbs a little, then comes back down.
I even abandoned fitting an over ride switch, but I always keep a close eye on my gauge.

Bernie.
bernie higginson

Nigel

Fan set point is a constant. Once set correctly as I described, you don't touch it. If water stat opens at a higher temperature - from changing it say - the radiator will still do its job and prevent the fan from kicking in - unless excessive heat is generated of course. Water stat should not cycle. Once open it remains open.

Cheers

Mark
Mark O

I tend to agree with Mark. I'm not convinced the dial on my fan thermostat is accurate and the temperature in the top of the hose (where I've fitted the thermocouple probe)isn't necessarily close to the average temperature in the block or the temperature at the regular water thermostat. In fact, I think I've sited the probe incorrectly; it would be better at the bottom of the hose so it is always fully immersed. Though a pressurised system with an overflow tank should theoretically always be full, in practice there are sometimes air pockets at the highest point, particularly if the car has been standing a while and there's a tiny leak somewhere. Assuming the dashboard gauge is roughly correct, setting to 'normal' is probably a good bet.
Nick Nakorn

I have never used the fan dial or the temp gauge to accurately understand coolant temperature. They are a guide only. Basically, if an electric fan is fitted you need it to cut in only if excessive heat is generated - indicated not only by the dash temp gauge, but also by the manner the car is driven - i.e. engine running whilst stationary, driving hard up a long hill on a hot day etc etc.

If after setting correctly the fan comes on more frequently or you begin to encounter run-on after switching off, then the coolant system needs looking at. The fan is emphatically not a substitute for an inefficient cooling system.
Mark O

Mark,
you're pushing on open doors with me about having a clean and efficient cooling/heating system (one of my pet subjects) and to set something correctly then leave it alone but you may have to experiment at first to find the best setting and later if you're doing something more extreme or you alter things then you could make use of the variable switch

I agree the gauge is just that, a gauge and that the figures on dials (car and thermoswitch) are only as a reference point - if you look you'll see I put that in an earlier post to Colin

having had cars with bigger engines and fibreglass bodies I'm very aware of heat build up and the need to restrict it, also having had at least five HGF, that I can remember (none in the larger engined fibreglass cars) I do tend to er towards the fan(s) cutting in a bit sooner rather than later to increase the margin from overheating


Nick,
this top/bottom hose placement argument rumbles on with advocates on each side, if you're not happy with the position of the probe then move it and let us know how you get on
Nigel Atkins

Nigel, I will if I remember! The car is still undergoing various mods and hasn't turned a wheel on the street yet.
Nick Nakorn

Nick,
when I saw the fan photo on the other thread I was thinking I'd have to put a securing strap between the two oil pipes to keep them level across the opening which is ridiculous as I'd never have the ability to have such a tidy car or keep it that way, plus of course I'd never bother with a oil cooler on a fully rebuilt standard engine, even the 1500, but that's where we differ even more, each to their own, different strokes for different folks, more than one way to skin a cat, etc., etc.
Nigel Atkins

This thread was discussed between 03/09/2014 and 05/09/2014

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