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MG Midget and Sprite Technical - remove thermostat or not

hi,i have just been given a electric fan kit for the midget but no instructions. question is do you have to remove the thermostat as someone told me you have to in order for it to work right it is the kit with the probe in the rad and the dail to set the temp.cheers


a moverley

The makers of the engine felt that the thermostat was needed to keep the engine within the correct operating temperature. A warmer running engine demonstrates less wear than a cold operating engine--one of the reasons behind the statement, "Most engine wear occurs during start up". I have used a kit similar to what you describe on three MGB engines, all of which have the thermostats installed. No problems even during the hot summers here in the Arizona desert. Thermostats set the normal, minimum operating temperature of your engine. It will run as hot at it needs to, within some limits, regardless of what thermostat you have installed (or without any thermostat). I would recommend you leave the thermostat installed. But, it might be worth questioning the individual who told you to take out the thermostat as to why he believes such necessary. Then, see if that reasoning makes sense to you. Why? is always a good question to ask.

Les
Les Bengtson

Ive havent heard that before.... I know they run stat free on some race cars

With a fan... Id put in a temp switch that would turn the fan off at 160 f and on at 190
Prop and the Blackhole Midget

An A-series engine requires the thermostat to be in place for correct coolant flow. Without the thermostat in place the water will not flow around cylinder 4 and it'll overheat there.

Racers who remove the thermostat install in its place a blanking sleeve to correct the water flow.

You don't need to remove the thermostat to make your fan kit work. All your fan kit does is draw more air over the radiator when driving at low speed. At anything above 30mph there's more than enough air flowing, even without the fan.

Removing the thermostat works if you're racing in hot weather- it takes a while for the engine to warm up since you have to heat all the water to the same temperature, but that same delay helps to smooth out hot spots in the engine. Perfect for high power steady speed running. Not so great for everyday or road use.

Growler

It sounds like you have a Kenlowe fan. Keep the thermostat fitted for all the reasons mentioned above, but in the instructions (I know you don't have any.....but,)it says to set the control knob higher than normal to allow your engine to run at a "higher and therefore more efficient temperature".
I would recommend that you ignore this instruction and set the knob at only just above the letter N, otherwise I feel that in traffic you run the risk of overheating and blowing the head gasket. Don't ask how I know. I now have it just above N and find it works great.
It also says to remove your mechanically driven fan blades. If you do, don't forget to fit spacer washers to compensate for the thickness of the removed blades. I removed mine and at first was a bit worried, but it does work.
It also may, for peace of mind's sake, be worth fitting an over ride switch in the car.

Bernie.
b higginson

The entire point of electric fans is that they only run when needed, ie, above max desired operating temp. That means the thermostat maintains minimum temp, and the fan limits max temp. So, the fan comes ON somewhat above thermostat full open, and shuts off likewise. Otherwise, the fan is fighting the stat, and runs all the time, which defeats the purpose. As example, my Mazda(s - x6)) has a stat that opens at 195F or so, fully open at 200F; normal engine loaded running temp is 200F. The fan comes on at 210-215F, and shuts off about 205, so the fans almost never come on, enough that it startles me every time they do. I set all cars up exactly this way.

With a 13lb cap and 50% glycol, boiling does not happen until over 250F. Engine temps around 200-220 are desirable for several reasons, especially for short trip cars, or when you want good economy - and heat in the car. Real race engine builders, who have measured and studied the subject for years, on dyno and track, ALWAYS run oil and water temps AT 220F.

Anybody relying on gauges which read "N" etc is a fool; they are not accurate, nor definitive of desirable operating temps. Measure the real temps with accurate instruments and "calibrate" your understanding of your gauge - they are all different, and their only valid function is to alert you of deviation from what is actually "normal" for "YOUR" engine. Electrical gauges in particular may vary greatly depending on the state of all other electrical components in the car.

FRM
FR Millmore

I run a thermoswitch electric fan and thermostat

I'd say remove the existing engine driven fan as it often cools the engine at the wrong times and you have the electric fan to cool anyway

Bernie makes a good point about the length of the fan blade fixing screws/bolts

personally I never see the need for an overide fan in a car like ours, you no doubt having been trusting to electric fans without overide switches in modern cars for decades, plus the extra wiring and switch could introduce problems and why have a dog and then bark yourself

a gauge is just that, keep checking them for the unusual but don't be oversensitive to them or you'll notice they can twitch and move around quite a bit
Nigel Atkins

FRM,

For those of us who must rely on factory gauges which read "N" etc., or even those who think they have proper gauges not calibrated on an annual bases. Is their a simple way that you recommend to measure the actual coolant temperature? Perhaps a (calibrated) inrared temperature gun (at a local service garage) aimed at the thermostat housing to see how that reading corollates to the actual needle position when the engine is fully warmed up?

Regards,

Larry C.
Larry C '69 Midget

ETA: another typo of mine, should have read
>>personally I never see the need for an overide - switch - in a car like ours <<
Nigel Atkins

Oh gez nigel,

Now you tell me... I just ripped that over ride fan right out of my truck, thinking it wasnt needed....hahaha

Your Just to cruel

Prop
Prop and the Blackhole Midget

you joke but I did consider whether a second staged fan was required on my car to cool it quicker as the single item is for standard output engines and mine is above standard - thanks to bits and bobs and oils, servicing and Peter Burgess tune up
Nigel Atkins

no, it's not needed Nigel. The electric fan on mine is of a similar diameter to the original yellow engine driven one (albeit has the advantage of being inside a round 'holder') and it cools the K series fine on a standard radiator.

If you set the temp cut in too soon it'll just run all the time. The fan on the K doesn't cut in until the needle is over halfway between the N and the white line near H, and no HGF or overheating yet, on an arguably more temperamental engine.

Also, feed the live to the fan relay from the ignition switched circuit, or it'll stay on after you've turned the engine off and over time upset the battery.

FRM said >>Anybody relying on gauges which read "N" etc is a fool<<

Not sure about that, after all, the gauge is just there to indicate when 'operating temperature' has been reached, and to let you know if something's wrong. The actual coolant temperature is not something that needs to be exactly right, for an engine like the A series there's a fairly wide range in which it will be happy ('colder' stat in winter anyone?) The N gauge does exactly define desirable operating temps, that's why it says N on it, for Normal. Any large difference from this is undesirable.

Rob Armstrong

Larry-
That'll work, although IR guns can be misleading if you don't use it right. Often, the aiming spot is not where the gun is actually reading, depends on distance usually, like focusing a camera. Or get a multimeter with thermocouple input, cheap today and very useful. Put the thermocouple against the top tank where the hose comes in, and use that to calibrate your gauge.

Rob-
OK, how many words do I have to use to get the point across?
>>Anybody relying on gauges which read "N" etc for accurate temperature figures is a fool<<
>>Anybody relying on gauges which read "N" etc to decide if that gauge is actually reading "normal" for his engine is a fool<<
>>Anybody relying on gauges which read "N" etc is a fool, unless he periodically calibrates the gauge against a known accurate laboratory grade reference, registered with the International Bureau of Standards <<
>>Anybody relying on gauges which read "N" etc to communicate real engine temperatures to other people who may or may not understand such gauges is a fool<<

What did I say here?:
Anybody relying on gauges which read "N" etc is a fool; they are not accurate, nor definitive of desirable operating temps. Measure the real temps with accurate instruments and "calibrate" your understanding of your gauge - they are all different, and their only valid function is to alert you of deviation from what is actually "normal" for "YOUR" engine. Electrical gauges in particular may vary greatly depending on the state of all other electrical components in the car.

I sort of thought that made it clear?

FRM
FR Millmore

Hi, I checked my temp. gauge with the brass sender sat in a kettle of boiling water. Conveniently the gauge has 212F marked between two small dots.
As clean water boils at 100C or 212F at or about sea level, that was good enough for me.
No need to take the kettle to the International Bureau of Standards for calibration!
My 40 year old gauge was reading plus 10F, just pulled off the needle and pushed back between the dots - job done.
Tony


Tony G

FRM,
Your chiding of Rob is a bit harsh and quite unwarranted! He was after all pointing out much the same as you, only in a less offensive or opinionated manner.:-) He too said that they are only an indicator when "operating temperature has been reached", and not to be used as an actual accurate measure.

I suspect that the change to the later dials with just the L-N-H face in place of the numbered dial was in fact because it was known that they were not accurate. What is important is to get used to where the needle sits on the dial in your particular car and to be alerted by changes to this "norm". If for any reason you do need to know the actual temperature then a different measuring method must be used, but in everyday life on the road this isn't what is necessarily important.

The L-N-H dials are calibrated; there are two pairs of very small dash marks on the dial face which correspond to standard temps (? and 100) and are used to set the needle in manufacture, but this still doesn't make the gauge accurate!
Guy W

More useful than the gauge perhaps would be an indicator light for when the electric fan comes on - provided the set point has been correctly set.

Clearly if it comes on in stop/start traffic, up a steep hill in hot weather, etc then fine. Anything else may well indicate a problem with the cooling system and should be attended to.

As many have said, it is the relative value that is important, not the absolute.

Mark O

Guy, and Rob, and everybody else.
I am sorry, I really do not understand why you guys are so touchy. I am talking to you as I would to a bunch of friends sitting around discussing things, maybe with beers or lunch. Which is how I think of all of you. And they talk back the same way. It's a friggin' joke! Elucidating the fact that production car gauges are not very good at giving real fixed information, and countering the constant flow of worrying about "my car is overheating, the gauge is above N" or "My car won't get warm it is always below N" etc and so on. Have another beer.

FRM
FR Millmore

FRM, I'll have a beer...........Are you buying ???

Alan.
Alan Cotterill

FRM,

Most of us on this site are hobbyist's, and enjoy owning and driving our cars for various reasons. Some are very skilled at maintaining, even re-building our cars from the ground up, and some are not. One of the more clever takes on the "L-N-H" temperature gauge was to look at it this way "L-N-$", and for the most part that's all most of us need to know.

This Saturday afternoon our club has a drive up to the Victory Brewing Co. in Dowingtown, PA. if your in the neighborhood stop by, and I'll buy you a beer.

http://victorybeer.com/

Regards,

Larry C.
Larry C '69 Midget

I've got my electric fan wired to operate after the ignition has switched off and I have no problems with the battery, I think that's how they are wired on modern cars

I have got an uprated alternator but I think the standard alternator in good condition would be fine, add in the fact I've also got an uprated starter motor and no auxilary components so my battery possibly has it easier than a lot of others

when the car is running I might need a light to tell when the fan is running sometimes but at standstill and with the engine off it is very easy to hear the fan working from even a distance
Nigel Atkins

FRM,
Maybe its a language thing! It wasn't the facts that you were imparting - as usual they are accurate and clearly based on many years of first hand experience. It was the repeatedly calling someone a fool when they are supposedly your friend. You seemed to be the one who was being a bit tetchy. A bit harsh I thought. So I said so!

Anyway , thanks for the offer of a beer! Especially as its the thought that counts, not the cost so a virtual beer is just as much appreciated! Cheers.

Guy
Guy W

Larry,
a great effort by the Victory Brewery but the style looks a bit to fizzy for me but to give them support you can have my , real not virtual, pint too (or are they on litres or 0.5l being Germany style) :)

if they servre it chilled (tut) take your temp guage in to make sure it's not too cold but check the guage is calibrated first :)
Nigel Atkins

I have an electronic post it note attached to my work computer screen.

On it is printed 'Never attribute to malice that which is adequately explained by stupidity' - a maxim sometimes called 'Hanlon's Razor'

I am given to saying really dumb things sometimes and occasionally I say it on the internet, I think everyone who posts on forums is probably equally guilty of that... I hope that no-one takes offence when I do because none is meant. Equally I try not to take offence at what is said by others by assuming they mean none either.

I'll take a metaphorical beer with FRM (wish it could be a real one with Larry too on Saturday, but sadly that might prove a tad expensive when I'd be travelling from Kent!)

Incidentally the question raised by the original poster was correctly answered by Growler
James Bilsland

Nigel,

We make this drive every fall. We cross several old covered (wooden bridges) on the drive up. I'll sample a few seasonal beers with lunch, but then again, I'm driving. Plus, as an option we have two winery stops on the drive back if you dare! Not too worry though my wife and I tag along to make sure all make it back with a break down, and to re-stock our pantry for the winter months.

Cheers,

Larry C.
Larry C '69 Midget

Larry,
by breakdown I assume you mean emotional and mechanical

I'd give the wine shops a miss and do more driving

great that you're getting some out on a good drive and I like the idea of see and crossing the old covered bridges - sounds like a great event, next time I have to drive my wife to drink I'll raise a glass of British real ale in toast to you
Nigel Atkins

The original poster appears to have deserted the thread, which is his loss since FRM is buying beer.
Growler

Reading this thread I thought I'd check my guage and like Tony G mine reads 'over'. As mine is early it does not have C N H but readings in F but it reads 10 deg F on the hot side.
Back to the original thread though I tend to ignore the guage a little as I have my thermostatic switch kicking in at a set temp that was calibrated by using a thermocouple & multimeter plugged in the top hose. Moral of the story is don't rely on old guages to be 100% accurate in temp reading but they will show what your 'normal' running temp is as they will sit at the same reading unless there is a problem, which is when you should worry.
I seem to remember (off topic)when the SD1 rover came out people complained of very low oil pressure, all BL did was change the guage so that rather than sitting at the 'Low' end of the guage it sat in the middle , it still ran the same pressure and they stopped getting complaints. A large number of modern cars don't even have a guage just a warning light if the car boils, so what you don't know won't hurt you I guess ............
Ed
Ed H

Ed,

During my first year driving I had a worn out '62 Chevrolet fully equipped with those "famious" warning lights. After a few weeks of driving I told my father the oil light was coming on at idle when warm. He patiently showed me how to check the oil level, and told me everything looked good and not to worry. After watching me check the oil level almost every evening when I came home from school he came out to assist again. Taking a page out of BL's book he got up under the dash (facia) and the light mysteriously never came on again. I later found out he removed the bulb!

Regards,

Larry C.
Larry C '69 Midget

I have a mildly tuned 1275 bored +.20 with a fast road cam, and the factory yellow blade fan. I'm pretty sure my t-stat is 165 deg.
Living in South Florida, a HOT climate, my car has never overheated, even when I drive it like I stole it.
When I hear folks complain about overheating I wonder if they don't have a timing issue or something else going on.
P Burke

Hi P Burke,

Well I wouldn't expect it to get overheated when you drive it like you stole it, since then, you'd be driving very carefully and within speed limits, so as not to attract the attention of the law enforcement agencies.

Well that's what I used to do anyway. lol.
Lawrence Slater

The "N" I referred to in my post was not on the gauge but on the control knob of the Kenlowe Fan.

Bernie.
b higginson

Bernie you fool that's the manufacturer's name :)
Nigel Atkins

many thanks to all for the advice and help but just one more question dose the probe just go in the rad and is there a way of making it stay put like soldering it on.i know that was really two questions cheers
a moverley

Depends on the type of probe some push fit between the fins in the radiator and others slide underneath the radiator hose joint.
Ed H


A Moverly
I had a nasty moment with the slide under the rad hose method years ago when after a service (not by me) the "Mechanic" lost the rubber fitting piece and just used gasket goo instead, blew most of the coolant out real quick.
I've soldered a brass fitting to my Rad in an appropriate place to take the thermoswitch on the 1500, works real well. This way if the temp is not right it's much easier to change.
cheers
Rod
R W Bowers

A,
if it's a Kenlowe then the probe usually slides into the top hose joint with a rubber piece protecting it as Ed and Rod have put

check the fan goes in the correct direction to cool the rad BEFORE even attempting to fit it in case like I had you have the wrong direction fan - I remembered to checked it worked before fitting but not direction which meant doing the wotk for a second time when they sent me the correct fan

also take the oppitunity to throughly clean out and check your cooling and heating systems (I have a simple method I can email you if you want it)

in photo below I don't know if you can just see the thin 'wire' (from probe to switch) just at the top hose joint


Nigel Atkins

Hi Guys
Just to add to the thread---

a moverley
are you still reading this thread


I'm just wondering if the salesman got a little mixed up between an electric fan and an electric water pump when he/she advised you to remove the thermostat
I had a very expensive (can't recall the brand) electric water pump system on a Chev V8 racer years ago which had a bypass system built into it and the controller (electronic - not you Prop) controlled the flow both through the engine and the radiator modulating between for temp. control The original thermostat had to be dicarded for it to operate as designed

just sayin Willy

If you are fitting an electric fan, check the blades to make sure you have either a sucker or a blower there are two very different shaped blades
Some people just reverse the polarity to get the correct air flow direction but the airflow won't be very good doing this
The fan has to spin in the direction that makes the concave side of the blade leed into tha air------
as mentioned there are two blades - suckers OR blowers

In my opinion an electric fan on a road car is more hassle than it's worth

over
William Revit

Fans I got have flippable blades, so you do that AND reverse the motor.
I can't find any electric fan hassle no matter how hard I try.

FRM
FR Millmore

FRM
Yep , some fans have blades that can be flipped but not all - some have the motor recessed into the hub of the blades making it impossible, With these it means getting the other blade set

My thoughts on electric fans on road cars are
why bother introducing several possible failure points such as
fuse
relay
electric motor
wiring
thermo switch adjustment etc
when the original pump mounted fan is basicaly foolproof

It might take a fraction of a horsepower to drive it , but the alternator will need the same power to drive the electric fan anyway
Willy
William Revit

perhaps you have less variable weather and traffic conditions in Tasmania than here, the engine driven fan runs when it's not wanted or required and runs slow when it's needed the most

the electric fan certainly isn't essential especially in a car with an engine in good condition and with its cooling systems working efficiently

but we've trusted electric cooling fans without question for decades now on the more modern cars

a chap in our club rerplaced his Kenlowe after 20 years of use, that seems a reasonable life time and it might even have been repairable

personally I don't see the point of some who retain the engine fan after they've fitted an electric fan
Nigel Atkins

This thread was discussed between 15/10/2012 and 21/10/2012

MG Midget and Sprite Technical index

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