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MG Midget and Sprite Technical - Heater and hoses removal, Midget 1500

Hi people, just bought a 78 1500 midget which is de-bumpered and styled like a little racing car. I only really intend to use it in the good weather so was considering taking the heater and hoses off, as well as the pipework that heats the inlet manifold. (Sorry, brand new to these cars, it looks like a hot water feed through the manifold). Anybody done this before? Is it a daft idea? Any pros and cons? Also... is it normal for the heater motor not to be wired up on this model? Mine is not. Lastly, a small metal water pipe coming off the back of the water pump, does anyone know of a blanking plug for these or what thread type please?

Thanks, Jon, Lincoln UK. Sorry new to forums so may not be up to speed with ettiquette, I only open the 'puter up every few days.
JE RYDEN

You live in Lincolnshire and you want to bin the heater?
Up to you, but I wouldn't.
The thread in the back of the pump is 1/2" BSPT I believe, if you want to plug it.

Oh yes - while I think of it. How about a photo of the car? Sounds interesting. We like photos!
Greybeard

Actually scrub that. It's not 1/2", probably 3/8". I just looked at the one on my bench which is off a GT6, but it's the same pump.
Greybeard

The factory heated the inlet manifold for a reason - the same reason that other cars use a hot spot or two from the exhaust manifold - it aids atomisation and combats icing.

As long as the heater valve is not leaking and the hoses are in good condition I would leave it all alone.

The heater may be disconnected due to electrical issues - reconnect the fan and see if it works.

Heaters are really useful even in warm weather - especially on the way home in the evening with the top down ....
Chris at Octarine Services

Jon, welcome,
lots of good weather in late-autumn / winter / early spring, many more so than summer so a heater could be very useful. If the cooling/heating system is clean and fully functioning then you will get plenty of heat to the small cabin or fett even open or roof down.

Following the instructions in the Driver's Handbook, keeping the fresh air valve/flap open at all times (unless sucking in congestion fumes) and you will get the most heat or fresh air.

If you've not already got one, the Driver's Handbook is a must for anyone new to the car, the original owners manual that came with the car when it was brand new, you can still get relevant reprints, from various sources, it is not the Haynes or Workshop Manual but covers what driver's need to know about the car plus the servicing and maintenance requirements (as of the time).

https://www.brooklandsbooks.co.uk/product/mg-midget-mk-3-drivers-handbook/
Nigel Atkins

ETA: Often the original heater fan motor switch is broken as it operates in a less than usual way (see Driver's Handbook) combined with the fresh air flap/valve mentioned before so that you can not turn the fan on with the flap closed (not that it really matters). Many cars have a seperate simple switch wired in and on, or hung under, the dash. The fan is only effective in moving more air up to about 25 mph after that the ram effect of the car moving forward will push more air up the 4" fresh air trunking tubing and through the heater box and heater matrix than the fan can.

It is important to have the fresh air tubing fitted fully and correctly at the front of the car, side of rad, rather than just lying somewhere nearby to get the full air volume and not have it somewhat dissipated.

Photo below is of a 1275 but the 1500 will be similar, but other sides of rad.



Nigel Atkins

The heater can occasionally also act as an emergency additional radiator for getting rid of excessive engine heat. Perhaps on a particularly hot day and in heavy slow traffic. It may not be comfortable putting the heater on full blast in these conditions but it can lower the temperature on an overheating engine and could save you from much worse and expensive problems.
GuyW

If you want to drive your car more than a couple of days in the summer the heater is essential in my opinion. Make sure you have the intake tube connected too, it makes a big difference to how well the heater works.
Chris Madge

Yes but surely you only turn the heater (tap) valve on for some of December and January.

Unless you're old like me of course, sunny, 9c, here today but I'd already got too cold to drop the roof, and forgot I'd left the heater tap open on to check the cooling system.

But for a fit, young(er) bloke like yourself surely the heater is not usually required.
Nigel Atkins

Nigel I’m clearly not as hardy as you. I used my heater for a lot of the summer especially early morning drives to work.
Chris Madge

Chris,
I'm not hardy in any way, other than perhaps sometimes foolhardy.

I wear coat, hat, scarf and often gloves, sometimes thermal long sleeve vests/t-shirts.

I must admit, yesterday I got cold beforehand, and kept the hood up as I felt even more lazy than usual - and the heater was on despite the mild weather as I'd forgot to turn it off so windows down so as not to overheat.

Today, another sunny dry winter day, luckily my wife was at work until it clouded over before we went for a drive. Once out of the metropolis the Xmas manic traffic was behind us and another fabulous traffic light run on the excellent Northamptonshire country roads. A missed turn in a village took us on a forgotten field road with cattle-grids and on roads where it alternated with the tyres and wheels getting covered in wet mud and rinsed off in the puddles. On to roads driving with caution but where 50 felt like 80 and a super or hyper car would have been soporific, if they weren't too wide to get stuck on the verges.

But again I must confess the roof remained u, and again forgetting the heater was on we both overheated and my wife complained her feet were blistering. At the (old age) pee stop I was going to drop the roof after but the wind chill factor changed my mind (literally chilly on the ...).

Tomorrow I will remember to turn the heater off and drop the hood as I'm just driving myself, a quick call in to the ale house for a swift one and when I get home at some point a double-curry (possibly cold) to myself - a billionaire couldn't live any better, and probably wouldn't think of such simple pleasures. As Joe Walsh sang, life's been good so far.
Nigel Atkins

It sounds like you are enjoying your car Nigel, it’s good to hear :)
Chris Madge

Thanks for all your comments and advice everyone, go on then I'll leave the heater and pipes undisturbed. Thanks for the thread advice Greybeard, the 3/8 BSPT union on the back of the water pump looks to have been weeping/spraying water onto the block, I'll have to give that a coat of looking at. I will upload a pic of the car once I get a decent pic, it's hardly been out of the workshop since I got it due to the weather plus it came with a goosed battery. Havent had an old car before, it's all really old bikes, magnetos and aircooled prior to this fancy contraption. Maybe that's why I was considering junking the heater, it looks like a plumbers nightmare under the bonnet compared to what I'm used to.
I didnt know about the heater flap in the footwell, brilliant. Still no sign of a switch for the fan, I'll get the multimeter on it shortly. Thanks again all, top job, all advice and comments really appreciated. Jon Ryden, Lincoln.
JE RYDEN

Jon,
even though thee cars have very little for the battery having a battery that is in good condition and charge and all its connections and earths in good condition and clean, secure and protected will help with running and problem solving - so a good new battery is a good bonus.

If you get a copy of the relevant Driver's Handbook, and if you read it and refer to it when required, then you will know more about the vehicles than many owners, even long term ones.

It will have a diagram of the 1500 heater valve (literally a tap off the cylinder head on the other engined Spridgets) as yours might be plumbed correctly, or not.

The heater motor switch would originally have been the twist part of the 'H' knob that should pull out from the dash to close the valve/flap that is inside the metal tube connector to the metal heater box that houses the the matrix and blower. Note the 'H' knob will only pull out (to close the fresh air valve/flap) if it is not twisted to turn the fan on and as this switch often breaks the switch for the fan is moved to another aftermarket switch.

The Drover's Handbook explains it a lot better than me, it's very simple once you know of its existence and unusual combination.

A sample of what the good book tells you, this is for an early model but the 1500 DH is much the same.




Nigel Atkins

1500 midget drivers handbook pdf download available here...

http://www.spridgetguru.com/AKD4386/AKD4386.pdf

Just sayin'...
Greybeard

Might be a little confusing as that's for a USA car but you'd get the idea of the vast amount of relevant information and instruction these books contain - allow for they were written for a standard new factory car over 40 years ago and some items have changed and improved in that time - but it's a very good starting point.
Nigel Atkins

This thread was discussed between 21/12/2019 and 29/12/2019

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