Aluminium Radiators - are they any better?

[PaulB]

Last summer I ran my Stag with standard reconditioned radiator, Revotec electric fan and no mechanical viscous fan. It coped OK just, but the revotec fan ran most of the time, and the engine occasionally got hotter than I would prefer.
I am considering two options. First is to replace the mechanical viscous fan and keep the original radiator and revotec electric fan. The second is to go with an Aluminium radiator.

I have approached a number of Aluminium radiator suppliers and they all say they are better than the original copper/brass radiator. However when asked how they justify that, none appear to have done any proper testing just saying they are better and they have good feedback from customers. They have also said using two fans is not a good idea as they would fight each other, which seems a rather dubious statement.

Isn't aluminium a poorer conductor than copper, so you would perhaps think that the original would be better?

A decent UK manufactures Aluminium radiator seems to be approaching £500 and I am reluctant to spend that amount of money if there is little or no benefit.

Could I ask what is the experience of other forum members?
Thanks.

[Motorsport Micky]

This question is often asked on many forums, choice is obviously yours but the standard copper radiators disperse heat far more efficiently than the alloy because of properties of the copper.
The racing fraternity use alloy rads because by getting rid of a bunch of copper pipes you can show a reasonable weight saving with an alloy rad and the requirement with racing is large amounts of controlled flow which a new alloy rad with oversize pipes can achieve easier (done it myself).
The copper rads are far more forgiving as regards vibration or flexing (in comparison alloy is a wuss) and can be repaired in situ if punctured or damaged, in my opinion a recored copper rad is the way to go if you consider yours is not satisfactory, you could take the opportunity to change the core structure if you wished to improve where you can, the airflow through it.

Micky

[mike@thenook]

Hi Paul,

There is loads on here if you search radiators but in a nutshell after extensive research the best performing rad was the original Mk 2 - a supergill type offers greater capacity (I have a Wards one) but ally is as you say a poorer conductor than copper and they are seriously pricey - only get one if you like the look of them being all shiny!
I'd say too that having run with just an electric fan and the viscous coupled one, I would always have the viscous one as it also keeps the engine bay a little cooler, an electric one won't do that.

Cheers,

Mike

[DJT]

I'd agree with the above. As an addition, I know a couple of Stag owners who have shelled out for shiny aluminium radiators, only to have them split a few years later, possibly due to work hardening. No recompense from the suppliers as they were out of warranty (and pocket!).

[022Dave]

Hello Paul,

Before launching into a large cost-outlay, have you done the basics to your cooling system? As you will find elsewhere on the Forum, the engine block is notorious for holding on to sludge & silt, and even original casting sand. It's easy to assume that the radiator is at fault for hot running, but doing a full engine flush, including removing the block drain plugs, and giving it a good rodding, could solve your problems.

Dave

[richardthestag]

I had an issue with cooling a few years back, dead viscous didnt help. nor did a sticky baseplate in the distributor, and the gauge did over read slightly but the biggest change was turning my header tank into a high level expansion tank. the plumbing in place allowed some coolant to bypass the radiator as the water pump would find it easier to suck coolant from the ht rather than the bottom of the rad.

[mole42]

My car has a viscous fan and a re-cored copper radiator.. it also has an electric fan in front of the radiator which is on a manual switch.. I have used the electric fan no more than two or three times in the last 10,000 miles.
Key point is to have your radiator re-cored, flush the system every year (10,000 miles for me) and make sure there’s no leaks.

[Phil S]

I have only covered about 200 miles since having an ally rad fitted along with some other work. the rad is from racetec and is about half as thick again as a standard rad. viscous fan has been removed and the fan fitted to the rad is stat controlled. sitting in traffic for 25 mins the fan came on once and the temp went down almost instantly. expensive but shiney and a nice ally expansion tank...time will tell!

[Stag_man@hotmail.co.uk]

If the everyone started buying the ally, it would probably effect sale of the copper so ones , just saying, I’ve done some digging and alloy stays cooler and is used in aircrafts , they would never use anything else .

[flying farmer]

You won't keep a standard stag cool by ram effect only which is why the fan keeps coming on. BTDT.

I tried moving from a 3 row to a 4 row rad and it made no difference whatsoever.

I really didn't want to re-fit the standard viscous air stirrer so I fitted a TR6 front spoiler. Problem solved, fan only comes on when stationary. Done that on both my stags now.

If you don't like the look of the TR6 spoiler the best option is to refit the standard viscous fan.

I would rather do that than fork out for an expensive alloy rad which will not fix the fundamental problem of lack of air flow through the radiator which, unfortunately, is a function of the design of the bodywork at the front of the Stag.

Neil

[STypeR]

For me a copper radiator for the sheer longevity and strength is preferable. I prefer the original way the tubes were staggered as well rather that the modern re-core design of behind each other. But this preference is heavily dependant on strong airflow. I don't like the 70's viscous designs; at idle they are spinning at around 750 RPM when most airflow is needed and no fan necessary say above 40 KPH..
Paul, I am not sure what size a 'standard Revotec' fan is that you mention. It could be that it is not at least a 16" unit and the amp rating of the motor is less than say19 amps. Anything less than this would not cope on the Stags marginal system; at least here with our Australian summers.
I would be checking this first.

[mike@thenook]

You won't keep a standard stag cool by ram effect only which is why the fan keeps coming on. BTDT.

I tried moving from a 3 row to a 4 row rad and it made no difference whatsoever.

I really didn't want to re-fit the standard viscous air stirrer so I fitted a TR6 front spoiler. Problem solved, fan only comes on when stationary. Done that on both my stags now.

If you don't like the look of the TR6 spoiler the best option is to refit the standard viscous fan.

I would rather do that than fork out for an expensive alloy rad which will not fix the fundamental problem of lack of air flow through the radiator which, unfortunately, is a function of the design of the bodywork at the front of the Stag.

Neil

Didn’t realise you’d ‘deleted’ the viscous fan Neil - what electric one do you use instead?

[Neil in Deal]

So many different views! I only bought my '77 Mk2 last year.
During the summer heat the car stayed perfectly cool, with the only exception being the temp. gauge moving up a bit during repeated "circuits and bumps" of Oxford services, trying to find a parking space!
I was quite content with the standard rad. and viscous fan set up, all through the long, hot summer.
However the viscous fan packed in in November.
So, time to make a choice Replace the defunct viscous coupling, and stay "standard", or....???
I opted for the large capacity aluminium radiator fitted with thermostatically operated pusher fan, supplied and fitted by Faversham Classics. (As I had no definitive date for the last block and system flush, Faversham carried this out, re-filling the system with correct strength anti-freeze, which with the imminent onset of winter was an absolute must.)
Whilst I'm content with the set-up now, I can almost hear the "tsk,tsks" from here !
However, we all love our cars, and want to do our best by them.
Sure, if you are happy with a standard set up, no problem. And I think the majority of Stag owners realise no matter what set up you have, the importance of an annual block and system flush, and correct type and strength of anti-freeze. And the nice shiny ally rad. top does bring out our "inner magpie" !
Whilst copper rads. probably do have the ability to remove greater heat from a cooling system than an alloy rad., this probably isn't really an issue with our temperate (normally!) climate. I'm certainly not going to worry about how many Joules (or whatever!) less the ally rad is dissipating, also the fan is set such that it only really ever comes on if you are held in stationary traffic for more than 10 minutes, so it doesn't really get the chance to get really hot.
So Paul, the choice is yours. If you had a standard set-up and were happy with it, sure, stick with it. If you want to make any modification, then go for it.
I look at my Stag as a "keeper", probably the only car I'll be able to afford and keep properly maintained, so I have gone along the big, ally rad. and electronic fan route. "Fit and forget"...hopefully!
All the best,

Neil.

[flying farmer]

Didn’t realise you’d ‘deleted’ the viscous fan Neil - what electric one do you use instead?

Both my Stags have two speed 14 inch Kenlowes fitted, the 2nd speed only comes on in very hot weather or when climbing mountains. Unfortunately these are no longer available. My Estate has a single speed fan of unknown type that I bought from a show at Stoneleigh.

IIRC it cost about £70 ten years ago because the £30 ebay fan went in the bin , I could fart harder than the ebay fan could blow.

The Estate doesn't need as much fan power due to the larger radiator and far bigger air intakes in the front panel

Neil

[mike@thenook]

Funnily enough that’s the exact type I have fitted as a back up- been on the car for well over 10 years has only ever come on in a serious jam in very hot weather. It has fewer but larger blades unlike the thin bladed high power ones that are available now.
I run with an 88 degree stat too.