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MG MGB Technical - A cold MGB GT

I bought my MGB GT as my winter car (I also have an MG TD). Maybe I was too optimistic. After som days in a shop, the warm air is still hardly noticeable. Yesterday I was using the car for the first time in cold weatrher, minus 8 degrees C. It was a very cold ride home.
This morning my son asked why I had not bought a heater to put inside the car, coupled to the cigarette outlet.
Nobody has mentioned this possibility when I have put the question in the Norwegian MG forum.
Any comments?
Raymond Wardenaer

Raymond
A typical cigarette lighter socket can provide 10A, that would mean any heater would have a maximum output of 120W approximately and this is discounting any power taken by a fan within the heater. I don’t think this would be sufficient heat to solve your problem.

I think your best bet would be to sort the standard heater. First you need to do the normal checks, is the engine coming up to normal temperature? If not you may have a thermostat stuck open. Check the heater doesn't need bleeding, check the heater tap is operating correctly and opening fully. Does the heater return pipe, the one that runs on top of the rocker cover get hot?

The standard heaters are known to be low on output and if all the above are working and you’re still not getting sufficient heat there are a couple of upgrades. You can get an up rated matrix, a 2 speed fan and an 88 degree thermostat. Having said that, I've done all these upgrades and mine is just about sufficient to handle a chilly day in the UK with the top down. With the top up it’s more than adequate.

Bob
R.A Davis

A well sorted standard heater system is more than adequate for UK use. But at -8 the cooling effect presumably means the engine is running colder. The heater cools it further meaning its not got enough warmth to get much heater output. Unless the engine produces sufficient heat that is not dissipated you won't get much heater output. I'd cover the oil cooler if you have one and also put cardboard in front of the grille. Cover part of the air intake in front of the screen. See if that makes the engine temp get up to normal and work from there. With little air flow queuing traffic might mean it gets a bit too hot.
Michael Beswick

You really should be running a 195F degree thermostat. Check that first.

Next check that your heater valve is not full of gunk. You will have to remove it so have a spare gasket.

You may have to block the oil cooler and radiator as mentioned by Michael.

I also have a GT and have plenty of heat at below freezing temps.
Steven Rechter

Hello Raymond,

I used my first GT for 2 years in CDN-winters(bad idea) and despite sometimes -25F, I never suffered "a very cold ride". It was not hot inside, but warm enough to have a clean windshield and acceptable interior temp..

In fact a 195F thermostat as mentioned Steve is first starting point. Only drawback, is obligation to swap thermostat two times/year.

Having your heater core cleaned in second good idea and checking heater control valve not partially obturated by lime is also mandatory.

And my last suggestion is having an improved heater (link below):

http://www.chicagolandmgclub.com/photos/b_heater/


Cheers,

Jean G.

P.S. I do not know how are roads in Norway, but in Canada with lot of salts used on roads brought my B-GT to Valhalla

J. G. Catford

I agree with what's been put already plus having a clean and fully functioning cooling/heating system is required to help with heating and importantly the cooling later

I have some notes you're welcome to a simple but thorough cleaning method that others have found helpful, just email me for them

the other side of having a warm cabin is to reduce heat loss and draughts which usually means checking/renewing seals - fresh air vent, door seals, fit of doors, insulation, etc.
Nigel Atkins

It may be worth flushing the heater core. If you disconnect the rubber hoses as they enter the heater and then connect a longer length of hose to get the discharge well away from the engine bay. Connect a garden hose to the inlet and turn the water on slowly. After the exit water runs clean reverse the hoses and repeat the process. Do not put to much flow or pressure through the core during this process or you may damage it. When finished hook the heater hoses up and make sure no air is trapped in the core. You should get improved water flow and better heating performance.
Max Irvine

I used my V8 for several years in all weathers including long periods of below freezing weather day and night and was warm enough, and the roadster heater can burn our feet, outputting 60C/140F at an ambient of 8C/46F.

There at least ten things that can contribute to poor heat output, see here: http://www.mgb-stuff.org.uk/heatertext.htm#pooroutput Get those right first before considering any 'enhancements, as some of the faults can prevent even those being effective.
Paul Hunt

This thread was discussed between 25/12/2014 and 27/12/2014

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