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MG MGA - overheating (again)

I have a 1600 mark I with crossflow alloy head oil cooler and both mechanical and electric fans which has always run hot. I removed the thermostat and fitted the sleeve as recommended In 30 mins in ambient air temperature around 20C it will reach 100C and can go to 120. I have flushed through and filled with Evans waterless coolant which solves loss of coolant through evaporation but have feeling it actually raises the temperature. The engine runs and idles happily at these sort of temperatures but obviously makes me nervous. Curiously cruising about 60/70 at modest revs in 5th gear it does not cool but I think that dropping to 4th actually cools it slightly, maybe because the engine fan goes quicker? I have read a mass of BBs but would like some clarification/comments. Moss offer an (expensive!) allow radiator which they claim increases cooling efficiency by 40% but Barney says that aluminium is less efficient than copper. On the other hand others have said it cured their problem. I see that fitting a shroud is recommended but I am not sure where and how they fit, also have seen one can obtain an after market version but have not seen them advertised anywhere. The modifications to the water pump leave me a bit baffled.
H L Davy

First step is to calibrate your temperature gauge in boiling water. then test your t/stat opening point in a pan of hot water and a good thermometer.
The Evans is not helping IMO.
Art Pearse

Not using t/stat. Before I melted the old temp gauge ( another story) it would always go around 212F
H L Davy

What spec is your current radiator? It is my pet source of overheating issues. The closer you can get to an original design core layout the better. I got mine from Bob West. He went to a great deal of trouble to source a rad builder who could build to near original specification. It solved all my colleague's overheating issue at a stroke. I also run one with my 1800 engine. I rarely get my temp above about 180, usually closer to 175.

Steve Gyles

I have a fan shroud if you want to make me an offer and collect it... (S.E.Hants)
P N Tipping

It maybe a long shot but what condition is the block itself? It could be packed up with accumulated sediment. As this has been a long ongoing problem I would explore that area,
I ran an A for years here in Florida and it never overheated. Today it was 91 degrees.

Great comments as usual on this site. Art I will check the sender. The car was refurbished some time back and has only done about 15K since. Steve for this reason I don't know how original the rad is. Noticing that a lot of people say they got bits from Bob West I asked him for a catalogue but he explained that he does not actually run a spares biz. Sandy I think the block is in good conditioon but if I have to clean it better I will have to overcome my laziness. I love this car but the carbs on the wrong side make reaching some things awfully difficult, especially the electrics. I would say to anyone thinking of fitting Xflow head - dont. Pete, yes please but have no idea of a price. Would you or anyone like to suggest one?
H L Davy

You may have misunderstood what Bob West implied. He does supply spares, but simply does not do a catalogue. Many of the parts are the same as you get from the likes of Moss and often carry the same stock number on an invoice. He specialises in rebuilds and upholstry. Also specific items that he considers he can do better than others. For me these have included the radiator, shock absorbers, carb exchange service, sports windscreens, wire wheel balancing and, most importantly, advice. You need to ask the right question to get the correct answer.

Steve Gyles

Thanks Steve. Would anyone like to comment further on alloy radiators? Am now off to Moss to get a new spring for my Minor Traveller which has just bust a leaf ( probably on dratted speed cushions) 2 days before the national rally. Grrrr.
H L Davy

I have two 1600's, coupe and roadster and both have a tendency to overheat. Our summer daytime temperatures are quite high, sometimes over 100F. Both cars get hot, I think because of the aerodynamics (ie no air through the core). I get the cores cleaned (ie rodded out) every four to five years and that seems to overcome the problems!
Barry Bahnisch

There are a few quite effective chemical cleaners that will rid your block and rad of scale. I remember using Holt's RadFlush once in the UK and it worked. Not sure if they still sell it.
Art Pearse

I really must determine why mine runs at 75C (even without the Judson installed) and package it for making a quick fortune on here
dominic clancy


Must be the altitude. Water boils at a lower temp up in those mountains!

Steve Gyles

Reading your original post, you say the engine seems to cool slightly better in 4th at 60mph rather than 5th. This makes me wonder if you are not looking at the water pump being faulty.

At any speed above 30mph the rad fan is more or less useless. The ram air is providing all the flow possible through the radiator matrix.
However, is it possible the water pump is ineffective? There are two possibilities, the impeller is blocked or spinning on the shaft.
If not the pump, what about the outlet pipe? It's not a great design and does tend to fur up with dissimilar metal corrosion from the iron block.
Paddy Reardon

The pump is newish but I may have to look at it.
H L Davy

Zurich is at 500m, which is a hill, not a mountain.
dominic clancy

Shroud for overheating at low speeds, ie, in traffic, will help. Do you have the felt block on the bonnet above the rad?
Try timing and mixture first before new aluminium rad. It is cheaper!
P. Tilbury

Also check your radiatorcap. If it has lost it's pressure, it will have adverse effect on the cooling.

When I fitted a 13psi cap on my MGB (just because it was looking better than the old one) I was surprised that it ran cooler (just before N, instead of just over the N on the dail).

I think standard caps have a lower psi rating.
Willem van der Veer

Wih Evans coolant there is virtually no pressure. I have a 123 electronic distributor - which I cant't reach - see previous comments on Xflow heads! I don't have felt block on bonnet. Where does it stick on?
H L Davy

Couple of pictures of the felt pad on my car.
Its the white felt pad that sits behind the black plywood board

J Bray

Another showing the pad laying on top of the radiator.

J Bray

There are a few times when my car or another I look after has overheated, and the reasons were:

1. The radiator cap was replaced and was too short so the system was not pressurised and losing water, a correct cap solved the problem
2. The seal on the radiator cap had shifted off centre and wasn't sealing so the system was not pressurised and losing water, centering the seal cured the problem
3. Timing was too advanced, retarding cured the problem
4. Mixture was too lean, making it richer cured the problem
5. New Moss radiator: no idea what was wrong with it, but putting in a unrestored 10Euro eBay radiator cured the problem. Every new Moss radiator I have encountered has caused a problem with the car, either because it leaked or didn't cool properly.

Maybe that will give you a few ideas.

dominic clancy

Mr Davy, Could you email me re: the fan shroud at
P N Tipping

Why not just switch to plain water and see the effect?
Art Pearse

Hey all, my 53 TD sometimes would run so hot the needle on the gauge would point to the top 200! I fought this issue for years until Peter from Highland automotive diagnosed the problem. The front slats were blocking the airflow. He bent them as open as possible and the problem disappeared. Hope this helps, Tom
Thomas McNamara

Steve mentioned the Bob West re-cored radiator. It was a huge improvement over the Moss radiator I had fitted to my car. I also recommend fitting a coolant recovery system (see Steve Gyles web site and Barney's information on the subject)and a fan in the cooling duct to the carbs (I guess they are on the other side with the cross flow head)is useful for when you get stuck in traffic; it stops vapour lock. 100C/212F is not a problem providing you have the correct pressure cap fitted to your rad, my car often runs 212F+ on a hot day in slow moving traffic without any ill effects. Normal temp at 70MPH is 190-200F. The trouble is that the MGA temp gauge gives too much information to the driver. If it was marked C-N-H you wouldn't worry half as much!
Lindsay Sampford

Similar to Lindsay's last comment, I was speaking to an MGA ownwr at GT-38 in Asheville last week who lives in Texas. Texas is a hot place, I understand well over 100F regularly. He says MGAs don't overheat in Texas. The owners are so used to 200 - 210F and above readings, that they just don't panic.
He repeated a theory I have heard before. "As long as they aren't boiling and spitting coolant out, they are fine."

L Poupard

This thread was discussed between 12/06/2013 and 20/06/2013

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