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MG Midget and Sprite Technical - Alloy radiator

The existing vertical flow rad in my frog has always been very close to the bonnet when closed ( steel bonnet). The rad has started to weep and needs replacement. I was thinking of an alloy rad and get them to make a slightly shallower header. The engine is 1293cc 'S' spec. Any experiences/ manufacturers?
Bob Beaumont

Interesting thoughts Bob. When I built my MGB V8 I decided on an aluminium radiator and spent a lot of money on it. From day one it leaked where the tubes entered the tanks, both top and bottom. Not a lot, but annoying all the same. So it went back and was "fixed", except that it still leaked. So it went back and was "rebuilt", except that when it came back it still leaked. So the supplier decided to have a brand new one made for me - great, except when it came it leaked also. So now I had two that leaked.

At this point I gave up and lived with the leak, topping it up weekly. Then someone told me about a wizard radiator shop in Glasgow, so I went up to see them. The owner hadn't one good word to say about aluminium radiators. In his opinion, they were expensive, were no more efficient than copper/brass rads, and they were very tricky to repair. In fact he did repair one of mine by smothering the area where the tubes enter the tanks with a special epoxy resin. Now I have a leak free cooling system for the first time in three years.

As to the efficiency, I have no proper data, but I notice that the fans on my car are on at least as much as on two friends' V8s who have copper/brass radiators. Would I go for aluminium again - emphatically NO.
Mike Howlett


Sounds like you got one from a dodgy maker. I worked for Ray Mallock Ltd for a short while and they made custom ally rads and they were all checked and leaks not allowed. IIRC one of the welders said they were tricky as the core was bonded together and you had to be careful not to overheat it or you'd get leaks.
David Billington

My radiators look fabulous with really neat welds etc. I bought them from a highly respected motorsport supplier in the south of England. The problems are all where the vertical tubes enter the top and bottom tanks. The flat surface of the tanks is pierced to allow the tubes to enter and its round these tubes that the leaks occur. The guy in Glasgow had to pressure test the radiator to 15 psi before he found the leaks, but that's the pressure the V8 runs at.
Mike Howlett

A brand new radiator that leaks does so because it has not been made correctly. It is of no consequence that it has been of aluminium and leaks.

It's true aluminium radiators for classic cars tend to be more expensive than a copper brass radiator. However, I suspect the reason for this is that an aluminium radiator is new and a copper brass radiator is always a re-core rather than brand new. Also, copper brass were mass produced and classic aluminium aren't.

An aluminium radiator isn't necessaraly more efficient as a heat exchanger than copper brass and in fact is less so like for like, and any radiator shop should now that. However, most aluminium classic radiators are more efficient than copper brass because of the core design whether more efficient in itself or more rows or thickness or whatever.

Modern cars have radiators that are plastic and aluminium unless I'm mistaken.

Mike - I'd name and shame that 'highly respected' motorsport supplier in the south of England for selling you a radiator with a leak and not fixing it. Fifteen psi is not a high psi for an aluminium radiator and I've expected it ought to have been tested at something between 19 and 26 psi.

I've run an aluminium radiator on my Sprite for over a decade if not 2 without problems. Back to back testing showed an improvement over a recently re-cored copper brass/unit.
Daniel Thirteen-Twelve

I run a Speedwell aluminum vertical flow model (made in USA) and it works very well. I understand that Tom, who owns Speedwell, builds them on a Ron Davis core--or has Davis build them to his spec.

Mine is a midget, but Tom shows his mounted in a frog:

Pricey but very well made. Slipped right into the mounts, the holes lined up, etc.
JM Young

Does it need to look period? If not, a lot of the kit car guys use modern plastic and alloy rads from small engined cars. They're dead cheap, as little as 40, widely available and come in a huge range of inlet/outlet configurations.
S Overy

Actually Daniel, I won't "name and shame" the supplier because they treated me very fairly. I bought the radiator while the car was in the building stage and it was a couple of years old before I got round to using it. For them to end up by having a second one made was beyond what they need have done as by then we were around three years from purchase date. The supplier was completely baffled as to why mine leaked as the manufacturer was carefully vetted by them and made a quality product, or so they thought.

My point is this. The aluminium radiator was about twice the cost of a new high efficiency brass/copper radiator from Clive Wheatley V8 parts, and I have found by comparison with my two pals who use that rad in their V8s that it is no more efficient at keeping the big engine cool. The aluminium rad is also thicker, giving extra problems with space around the cramped engine bay of the MGB V8. So why pay the extra? I wouldn't do it again.
Mike Howlett

I don't understand why your vertical rad should be close to the bonnet, surely that's the way it designed.
Also my downflow rad copes very well a 1330 high cmpression engine and central london traffic.
frogeye Gary

I had a RV8 in a car that used to run very hot from manufacture I swapped the original otter switch (to a lower temp IIRC) and that made all the difference on a 4.3 in fibreglass

I never had heat problems (that I can remember) with my SD1 engined B roadster, standard old rad
Nigel Atkins

Thanks Gary

It has always been close ever since I had the car.In fact there is evidence of the rad just touching the bonnet. I have set it back slightly on spacers to give more clearance. The car has never to my knowledge had an accident and everything lines up ok. Given its rad has now died and I need a new one I wondered about going alloy. Given the comments about performance and quality I am not sure there is any real benefit. I am now thinking of getting a slightly shorter (5mm) core and rebuilding the original. I don't have any overheating problems although I don't have a thermostat.
Bob Beaumont

This thread was discussed between 14/10/2012 and 22/10/2012

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