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MG MGB Technical - overheating mgb

i have a 1964 mgb, where the average temp is 34 to 37 centigrade. in normal running, the water temperature is about 140 to 180, but the minute the car is stationary for 5 minutes it starts climbing to 220.
it has a thermostat at 88 degrees. i intend to remove the thermostat, and put put in a blanking plate.

i also intend to fix a electrical fan. the question is i need a wiring diagram, and any advice would be very helpful
thanks
vignes
vignes pillai

the electrical fan will be fixed in front of the radiator, as a blowing fan , and i will maintain the 3 blade metal original fan, behind the radiator
vignes pillai

Vignes,

I had exactly the same problems with my 1963 MGB. As soon as the car stopped, it started to overheat.

The solution for me was a fan shroud. Part no. 60.

http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=7974#60

The difference is remarkable! No more trouble with traffic jams.

I donīt think it is a good idea to remove the thermostat, but you can install a 82 or a 78 degree one.

Tore
Tore

THANKS TORE, I ALREADY HAVE A SHROUD. I MAYBE WRONG , BUT THE OUTSIDE TEMP IS 34 TO 37 C. I THINK IT PLAYS A PART. I HAVE CLEANED THE RADIATOR ALSO.
vignes pillai

Pointless keeping the mechanical fan. They run at their slowest when you need them most. i.e., when stationary and will do nothing to enhance the efficiency of the electric fan. !! Also your thermostat is much too hot, MG used 74deg in "warm" climates.When you change it make sure the new one has a bleed in it. If it hasn't drill one.
Allan Reeling

You are probably right, Vignes. The Norwegian climate is not that hot. Having said that, we have had a few days this summer with temperatures just above 30 degrees, and the MGB has not overheated.
Tore

My 6 blade plastic mech fan kept mine constant at under N under normal driving and only crept up towards the N when in traffic for a while, only then did I have an electric fan as backup operated manually by a switch on the dash, put in an 82deg stat and get the 7 blade plastic mech fan from Moss or ebay
D Linkson

my car is a 65 roadster , which has a long nose water pump and the pulley too has to be changed , if i get a 7 blade fan.
vignes pillai

Vignes,
it's as Allan has already put

why on earth are you running an 88c thermostat in a hot climate like yours!?

you should be running a 74c thermostat (for hot climate)

changing from 88c to 74c should help, if not you have other cooling issues

and I agree with Allan if you install a good electric cooling fan with a thermoswitch to operate it then you can do away with the engine driven fan which often works in the opposite way to what is needed
Nigel Atkins

Firstly a car is only overheating if it starts losing coolant or is steaming. The 'normal' range for the MGB can be anywhere between just above C and just below H on the CNH gauges, which equates to about 120F to 212F, or 50C to 100C, so 220F does need looking at. Whilst 34C is pretty warm the UK can get up to that and more occasionally. One day approaching 30C and inching forwards in heavy traffic mine got up to the edge of the H zone, but I didn't suffer any coolant loss.

Secondly these cars run in desert states without problems, so for anyone experiencing problems at less than that there is something that needs fixing, not modifying.

There can be a number of reasons why the coolant is getting hotter than one might expect, ranging from the engine producing too much heat which might be because of ignition or mixture problems, through insufficient flow through the circuit from either restrictions or corroded pump vanes, to the radiator not getting rid of as much heat as it should perhaps through partial blockages. You can get an idea as to which area a problem might be in my measuring the inlet and outlet temperatures of the rad. If the inlet is 'high' but the outlet is 'normal', then the implication is that the flow is reduced for some reason. But if the outlet is 'high' as well, then it's either too much being produced or not enough being got rid of. If you scan the surface of the rad with an infra-red thermometer, you might find cooler spots instead of a gradient from inlet to outlet. If not, and there is nothing blocking the air-ways through the core, then the implication is the engine is producing too much.

Also check the fan is correct i.e. sucking instead of blowing, it is the right way round, and that you have the right combination of short-nosed pump and spacer, or long-nosed pump.
Paul Hunt

Paul is absolutely right. I've had several 1800 B's non with over-heating problems, quite the contrary, over-cooling if anything with oil cooler and no oil stat.
Apart from Paul's references to water flow etc., Having too lean a mixture will generate more engine heat. As will having the timing too advanced. Both effects will be worse at idle.
Allan Reeling

Paul,
If the fan is the wrong way round, it will simply lose efficiency, not go from suck to blow.

A hoary old chestnut.

(I deliberately had the fan on my 5-bearing Magnette on backwards for a couple of years until I got around to improving the clearance between the radiator. No problems in 35C temperatures.)

David
David Overington

David,
Paul means two separate issues, that the fan is the correct type and then is also fitted correct way round

see on Paul's excellent web site mgb-stuff.org.uk the section 'Mechanical Fans Added August 2007' and you'll see he's meaning the same as you - http://www.mgb-stuff.org.uk/coolingtext.htm#drainfill
Nigel Atkins

"two separate issues, that the fan is the correct type and then is also fitted correct way round"

Exactly so, although the link is http://www.mgb-stuff.org.uk/coolingtext.htm#mfans. I've seen a mechanical fan fitted to a late MGB with electric cooling fan, and it was blowing at the back of the rad. It was obviously non-standard, but fitted in the same way as the earlier factory-fitted mechanical fan were. It proves the point that a similar non-standard fan could have been fitted to any MGB.
Paul Hunt

sorry I missed that direct link as I was scrolling down the page reading
Nigel Atkins

thanks everyone for the advice.will do the necessary checks and get to the root of the problem.
vignes pillai

At the risk of stating the obvious, have you double-checked for any airlocks in the system?

Any trapped air will mean instant boiling.

And/or that it really dos have the right amount of fluid in it- i was surprised how long it took to get that last half litre into mine when I refilled it.

Apologies if i offend with my lack of model-specific knowledge being new to this, but does your have a heater? Prime place for airlock...
R Kelly

You can get air locks, after draining and refilling it helps to have the nose a bit higher than the rear for its first run up to temperature. But other than that a few heat-cool cycles should be all that is necessary to purge it of air. The rear fill rad is tricky to get right as the tops of the tubes are out of sight. Really that needs to be checked when still part warm, so see if there is coolant visible. If you check when fully cold and add till visible, when it warms up next time it is likely to chuck some out of the overflow as excess, and so will be out of sight again when fully cold.

If the heater does air-lock that won't adversely affect engine cooling, just the functioning of the heater itself.
Paul Hunt

This thread was discussed between 29/09/2014 and 01/10/2014

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