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MG Midget and Sprite Technical - Electric fan. Blow or Suck

I have a 1977 midget to which I wnat to fix an oil cooler and electric (Kenlowe) fan. The fan I've bought is from Moss and has the description "Blower". I asked them where it should be fitted and they said bewteen the rad and the bunper. I queried this with the tech guy at MGOC who said it should go between the rad and the engine. I've been told the expression "blower" refers to the fact that the fan blows the heat out of the engine bay but I've also heard that it means it blows the cold air into the engine bay. Can anyone give me a definitive answer.
K Montgomery

A blower fan goes in front of the radiator a sucker fan behind.

You bought it from moss and they say it goes in front, then why ask an MGOC tech guy who does not know exactly what fan you have (Kenlowe do both)?
Now you ask here?
do you want to be confused?

The function of the fan is to give airflow through the radiator when needed and when the speed of the car will not provide it.
When standing still or driving slow it is.
The fact that this also gives some fresh air in the engine bay is a happy side effect.
Onno K

Like Onno and Moss say a blower is to be between the rad+bumper to Blow air thrue the rad into the enginebay

A sucker is positioned between the rad and engine and sucks cool air thrue the rad into the enginebay.

There are two camps on this one say sucker are better the other believe in the blowers.

There is nothing wrong with the type of fan you bought aslong as you place as its manunual/instruction says.

I can understand you get confused if a techguy from Moss tels you this and a MGOC says differently.

Connect it with power and feel what it does so you know for sure if its a blower or not.
Arie de Best

note the exact model number of the fan and contact Kenlowe

I bought a Revotec fan as part of a kit that goes in front of the rad, I tested it before I fitted it but forgot to check which way it moved the air

after a warm run in the car and a smoke test I discovered it moved the air in the wrong direction

it was difficult to persuade Revotec of this as they "are extremely careful with the pakaging and wouldn't make a mistakes"

after standing on my head and trying to read a very small label at a distance I gave Revotec the model number and they conceded I had the wrong fan and got the correct one to me the next day

I'm still sure that the fan would be better if moved just a bit more air but it does do the job
Nigel Atkins

Hi mate

No need to get too confused Electric rad fans are extremely simple devices to fit and understand.

You need to know a couple of facts however.

The first is that

A blower fan describes a rad fan that is fitted in front of the radiator and blows cool air into the radiator
A sucker fan is fixed behind the radiator and sucks air through the radiator

This is simple I think you will agree.

Now a fan is a DC motor with a fan blade attached, the majority of DC motors can spin in either direction dependant upon the polarity of the wires. This means that if you reverse the conections you will reverse the direction of the motor and the fan blade. This means that reversing the connections of a blower will make it a sucker and visa versa.
Whilst this sounds easy it is not to be advised because the design of the fan blade is engineered to be efficient only in one direction and whilst it will operate in reverse it will not be as efficient as it is designed to be.

So before fitting, connect the wires to the correct polarity of the battery (pos to pos and neg to neg) and when the fan spins feel which way the air is being blown/sucked this will ensure you will fit it correctly to your radiator.
Robert (Bob) Midget Turbo

only saying from my encounter with Revotec and only if my memory is correct and often it isn't and only refering to Revotecor the Revotec fan motor

the Revotec fan motor doesn't reverse polarity

I had to take the cover off my bathroom extractor fan to see which way the fin/blades(?) should be angled for direction of air movement to further check the Revotec fan I'd originally been supplied
Nigel Atkins

Nige the angle of the blade is not the issue, if the blade is reversed the angle of the blade is the same, the issue when the motor is reversed is that the opposite edge of each blade becomes the "leading edge. If you look at each edge of the fan blade you will see that each is slightly different and the shape is not the same when reversed.

However that is all difficult to explain so I will just stick to my above post it is very simple.
Robert (Bob) Midget Turbo

The one thing not mentioned so far is that in either position the fan wants to be as close to the radiator surface as possible. The blades should be just skimming the fins, without touching them, obviously.

It is generally thought that a "sucker" behind the rad is slightly better, although I've never had a problem with the "blower" fans on my V8 MGB. On my 1966 Midget I found it convenient to mount the fan (a "sucker") behind the rad, inside the shroud and right up against the rad surface.
Mike Howlett

sorry Bob what you put is what I meant by my over simplified use of the word angle

are you able to help me with my wiper motor thread at all please
Nigel Atkins

Read thread with interest as I am thinking of fitting an electric fan. Can I ask a couple of questions please:
1. I was thinking of fitting a blower style fan and leaving the original fan in place. What are the pros and cons please? I am assuming on a cold day it is better to have no fan running when warming up, but other than that?
2. Kenlowe seems to be the fan everyone talks about but there are some much cheaper ones around like http://www.ebay.co.uk/itm/Electric-Radiator-Cooling-Fan-12-Push-Pull-Universal-S-/190435099935 for £19.99. Are there big differences?
Thanks
Graham M V

Strictly speaking, as regards the fan itself any fan both sucks and blows. By this I mean that any fan operating sucks air in from the upstream side of the blades and blows the same volume of air out of the downstream side. So the definition of a sucker or a blower is more to do with where the fan is mounted. However it is mounted, it is important that the air propelled by the fan can only go through the rad, and not spill out around the edges. So baffles and shrouds are used to ensure this.

Fans upstream of the rad ( a blower fan) do obstruct the air flow more so that arrangement may be considered less efficient at higher road speeds. But generally ( at UK temperatures) these things are not that critical. In terms of engine accessibility a fan mounted in front of the radiator, giving a clear space in front of the engine is a considerable benefit.
Guy

Main reasons for using an electric fan are that a) it avoids over cooling which can occur with a normal fan running all the time. b) reduces engine hp loss by driving a mechanical fan and c) a significant reduction in noise.

Why would you want to keep a mechanical fan when you have an electric one installed?
Guy

my thoughts;

yes when the engine is cold and the revs are higher the engine fan is working against warming the engine

(warmed engine) when car is stationary or low speeds you've lost the rammed cooling air passing through the rad and the engine fan is going slow when it wants to be going faster so the electric fan will help

engine fan take a bit of engine power and so do does the electric fan via the alternator so both together will take more this may effect your tick over and fuel ecomony a little

if your electric fan doesn't work then it doesn't matter as you have the standard engine fan still

personally I'm fully commited to an elctric fan only with thermoswitch and no overide switch to manually turn it on my view is buy a decent fan and thermoswitch and let them do the work it's what's been in 'modern' cars for many years and you've probably accepted it without worry or even thought

if you feel the need for back up of an overide switch and/or engine fan then fine but you shouldn't need it was a good electric system

whichever fan the complete cooling (and heating) system with all parts clean and in good condition is required and more important

coolant should be changed regularly even if the anti-freeze part still works

and engine oil in good condition also with cooling

ETA: not arguing just saying, I didn't notice much drop in noise when I took my engine fan out but you sure can hear my Revotec fan fitted in front of the rad when its going
Nigel Atkins

How many modern cars use a mechanical fan? None? That's for good reasons.

As stated earlier - the fan is not needed for most of the time; but absorbs power all the time.

The fan has be spun fast enough (with blades at suitable angle of attack) to keep the engine from boiling at idle when car stationary on the hotest day - the 'worst-case' situation.

At 5x the revs, say when cruising, the fan is running very inefficiently - absorbing much more power but not pushing proportionally more air.

Fans spun by the engine are always pullers, since they don't need a shaft passing through the radiator.

Additonally, when a fan over-speeds, it tends to send more air radially (outwards) than axially (forwards); so for engine-driven fans that will overspeed, this would favour pullers, since proportionally less air is pushed forwards (axial) when over-sped.

However, elecric fans are designed to always run at optimum speed, and (esp when ducted to reduce radial flow) will likely work just as well pushing or pulling. But don't forget all pullers need to be close to the radiator, so air doesn't leak into fan without passing through the rad core.

On moderns, fans are always ducted and often mounted on the radiator to prevent leakage; sometimes you have 2 fans to 'double' the cooling instead of over-speeding a single fan. Whether they push or pull depends mainly on room in the engine-bay.

I've not used an engine fan since the early '90s. Before that, I chopped the blades on my plastic fan to 2/3 size - still kept the engine fine at idle (at UK temps, that is...) but used less power at higher revs.

HTH

A
Anthony Cutler

Thanks, that's pretty unanimous. I will remove my original fan.
Anyone tried the cheaper fans like the one in my posting above. The kenlowe set up is not cheap, so wondering if I can save some money here, or whether that would be a disaster?
Graham M V

Mine's an early 90s Cavalier fan in front of the rad (reasons of space)... originally switched on manually... well, it's easy to figure when the fan's needed. On the very rare occasion my wife needed to drive the car, I'd just leave in 'on'.

Now it's controlled by the Emerald ECU; still have the over-ride switch (actually I use the panel-lights switch for this...) but can't remember ever having to use it.

A
Anthony Cutler

A lone voice speaks . . . .

1500 Midget 1976 . . . . . owned since 1978. I have never been happy with the Kenlowe as (sole) means of rad cooling. True, my engine bay is well insulated with felt, primarily for sound insulation. But I always found the (Kenlowe) was not up to the job of keeping the under-bonnet temperature controlled in high summer on the gridlocked London roads (ambient temps >25C).

I know I am in a minority of one LOL - but even with a new Serck radiator, my engine temps just run too high with a Kenlowe. Irrespective of thermostat temperature version (I have tried various from 74"C upwards). I start to get twitchy when water temp reaches 88C.

I don't buy the argument that 'modern cars have electric fans, so they must be appropriate for a 1500 Midget, too.' 'Modern' cars tend to be thoughtfully designed from their inception. A 1500 Midget isn't 'designed' as such - it crudely evolved over some 40+ years. Dare I say it, its end form is a result of a succession of bodges over several decades.

Specific to the 'engine cooling' debate, these bodges include: rubber bumpers (blocking air flow), carbs and petrol float chambers sitting a few inches above the exhaust mainifold/downpipe, tiny cross-flow radiator, inefficient 1500 engine shoe-horned into an inadequately ventilated engine bay.

Yes, the engine driven fan is noisy and 'working 100% of the time' - but an experience stayed with me from 1985(ish). During a rolling road session, a test was done with (a) just the electric oooling fan and (b) the engine driven fan. There was a marginal increase in BHP when using the engine driven fan. This was put down to better under-bonnet temeprature control rather than relying on the Kenlowe alone.
Andy Hock

I fitted an electric fan to my 78 1500, being a cheapskate I bought one from ebay and from memory I paid under £10 inc P + P, again from memory it came from a small Citroen or Peugeot. I already had a Kenlowe thermostat and used it in conjunction with a relay to drive the fan, I also used the Kenlowe light and switch. The fan is a pusher and sits in front of the rad, it was the biggest fan I could fit in the space. It did require the shroud to be cut and welded with the addition of an extra piece to clear the top of the fan. Interestingly the slam panel has a cutout that allowed this to fit without alteration. I cut and welded the bottom of the shroud so the rad and shroud can be removed while leaving the fan in place.

This arrangement works really well and whereas previously if struck in traffic the engine would heat up until it would barely tick over, now the fan cuts in and it never gets above one notch above normal (later gauge without temp markings)

If I had the space between the engine and rad I'd like to try a puller fan, it strikes me that having the fan in front of the rad shields a proportion of the rad, also the air flowing through the fan (if the fan is off) will lose some of its energy and therefore have less to force its way through the rad.

I agree with Andy, I believe the airflow on the 1500s is seriously compromised.

As per earlier posts, modern fans are only designed to work in one direction, most will operate in the wrong direction but won't be efficient.

Bob
R.A Davis

Andy.You're not a lone voice. I bought a Kenlowe fan, the correct one for my car ('65 Sprite. Radiator has a new core). I fitted it as per instructions, set the thermostat relatively high, as per instructions, removed my mechanical fan blades as per instructions, drove the car and in traffic nervously watched as the temperature climbed, heard the fan cut in and saw the temp very slowly come down. This happened every time I got in traffic until it eventually blew the head gasket. I was not impressed, so I repaired the gasket and refitted my mechanical blades. Now the engine does run a little on the cool side, but at least my HG is intact. I may try again with the blades removed, but this time set the stat lower and fit an over ride switch.

Bernie.
b higginson

This thread was discussed between 31/05/2012 and 02/06/2012

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