Aluminium Radiator – An Interesting Journey.

The following story is a journey of what the writer thought would be the ultimate cooling system solution, but then the problems reared their ugly head. Others may have had better experiences, but this is mine, hope you enjoy the read.

The year of 2008 dawned just like any other year. But in Australia, new year falls mid summer, presenting amazing weather for very early morning sports car drives, commonly called EMR’s, which often include a breakfast stop, or at the very least, a morning coffee stop along the way.

As the seasons come and go, we keep driving our cars, and sometimes we hardly give a thought to what condition the various components are in… as long as the instruments tell us that everything is normal, that’s about all we need to know, isn’t it!

Like most lotus elan cars, the writers S2 had always been fitted with the traditional copper/brass radiator, the type with the filler cap perched on top of the upper header tank.

But during the month of August 2008, disaster struck, when a mechanical component failure resulted in an off road excursion resulting in significant damage to the Elan body, as well as the front and rear suspension components.

What followed was a four year hiatus, the car was taken off the road to undergo a major body, chassis, suspension rebuild. At this stage of the cars life, the engine was still in good shape, so nothing was done to it, but we made sure that it was nurtured and preserved during this quite long “no run, no drive period”.

The writer never liked the old style copper/brass radiator that was in the elan, it was a bad design, had been repaired far too many times, and it was always weeping, the constant reminder of leakage was the pungent smell of coolant bitters on a hot summers day, I guess it was just the nature of the beast, but it was time for a radiator upgrade.

But the pending upgrade to the cooling department raised some questions.

The first of course was, what type? And where does one source a new elan radiator? Residing in an Australian regional area, commonly known as “out in the bush”, means that the local radiator shops are limited in what they could provide for a lotus elan.

Like most people, an online search was undertaken to see what was available, the requirements meant that the new radiator would need to be custom designed and fabricated aluminium cross flow product.

There are several companies producing lightweight, highly efficient aluminium radiators, or heat ex-changers as they should be called.

Having spent a considerable amount of time with online research, the decision was made to go with a company based in Queensland.

After a couple of emails, phone calls and ensuing discussion, we commissioned the QLD company PWR to produce an aluminium cross-flow design specifically for the lotus elan, the cross-flow design also meant that a surge tank would be required which included a radiator pressure cap for filling, plus an overflow nipple where a hose could be attached to feed excess coolant into the expansion – replenishment tank, this design also meant that the cooling system was sealed just like a modern day cooling system.

The PWR design department was meticulous in providing CAD drawings to peruse and to make detail changes if and when required before the drawings were signed off and forwarded to the production shop.

One particular design that we incorporated was to get rid of that silly snake like bottom radiator hose that is peculiar to the lotus elan.

The design change was cured with an angled “up-kick” addition to the bottom rad outlet neck which allowed a common 90 Deg elbow radiator hose to be connected… Ugly, snake hose problem solved.

There are many well known benefits of employing aluminium radiators.

The main one of course is that they offer far superior cooling efficiency than the older copper – brass items. They offer a significant weight reduction over or near the front axle line for the elan. Not to mention that polished aluminium radiators look magnificent under the bonnet… they present a bit of wow and bling factor to the engine bay.

The big drawback is the cost, (Unless you buy a Chinese made unit) aluminium rads can be significantly more expensive than the copper-brass radiator, so if you are thinking about going down this route, be aware that the build-install cost could blow out to more than you expect.

I mentioned above the very low cost Chinese aluminium radiators, these can be had for about $250.00, but I wouldn’t think that any specific-unique custom built add on’s could be had for that cost, I would be more comfortable buying local and knowing that I am going to get what I want for the extra cost, and have some back up warranty…if…when…required…. And we did… but more on that a bit later.

The writer has been a fan of aluminium radiators for quite some time, but the enthusiasm has waned somewhat in the recent past because of some unforeseen problems that have raised their ugly head, and we will cover those details shortly.

We’ve already given hints as to the aluminium radiator manufacturer is. We wont hide that from you, the make or brand of radiator we chose was PWR Performance Products Queensland Australia. Their product is of exceptional quality, made from the highest quality material, and put together by highly skilled fabricators and TIG welders.

We are not here to rubbish the PWR brand, as the problems that we encountered could have easily occurred with any other chosen high quality brand of radiator.

There are several factors that will contribute to the failure of an aluminium radiator.

1 – Stray current – which can emanate from several sources. (YOU MUST test for stray current).
2 – Use of domestic tap water in the coolant mix.
3 – Incorrect type of coolant employed – (Recommendations are to never use green glycol coolant).
4 – Neglecting to thoroughly flush and clean and neutralize previous coolant used in the engine.

The very first aluminium radiator that we obtained for the S2 elan was purchased a very long time before it was actually installed and put into service. Whether this had any bearing on the outcome and subsequent short life span experienced is unknown. But the biggest problem that occurred was that by the time it was installed, the factory warranty (12 months from manufacture invoice date) had already expired, and the weeping problems began within four months of installation, and you could imagine the frustration that this created.

The above picture indicates green coolant, and we’ve just outlined the problems, well this was a time when the writer was not aware of the problems from not using the correct type of coolant with aluminium radiators.

How to tell if your aluminium radiator as been subject to stray current attack.

If you have never had any experience with aluminium radiators, you might wonder what the dickens stray current is? Stray current can be caused by poor electrical connections, particularly a bad earth. It is difficult to trace and understand where the current is coming from. (And don’t confuse it with galvanic corrosion)

Stray current is measured in milliamps, and can only be measured with a digital multi meter, the general rule is that, if the measured stray current is in excess of 0.05 milliamps, your bright and shiny aluminium radiator is not going to last very long. The tell tale sign of stray current is a blackening of the internal surface of the aluminium header tank, a radiator with a very low reading (0.02), means the internal aluminium surface will remain bright, clean and shiny.

Never, ever use ordinary domestic tap water for mixing the coolant concentrate. Tap water has all kinds of nasty minerals, which will contaminate the coolant mix. Always use de-mineralised or distilled water to mix the coolant in the correct ratio… DO NOT vary the manufacturers mix ratio guidelines.

Aluminium radiators should only have one type of coolant and that is the red coloured type, we happen to favour the Penrite RED OEM COOLANT CONCENTRATE.

Red OEM Coolant Concentrate is a GENUINE GLYSANTIN® G40® Original Equipment Manufacturer (OEM), Fully Licensed and Warranty Approved, Type “A”, Ethylene glycol, Anti-Freeze Anti-Boil CooIant as used in initial manufacturer factory fills. It uses a technically advanced Si-OAT (Organic Acid Technology) based inhibitor system that is Phosphate, Amine, Borate and Nitrite free. The extended long life inhibitor formulation prevents rust, corrosion, cavitation and degradation of the cooling system for 8 years or 500,000km.

It is available in both concentrate and premix formulations. When changing from the green glycol coolant to the OEM red, it is paramount that the cooling system be totally flushed and cleaned before filling with the new red OEM coolant, failure to thoroughly clean and flush remnants of old coolant could lead to corrosion problems in the future with an aluminium radiator.

If red OEM is mixed with green glycol type, a chemical reaction will occur, resulting in severe corrosion and failure of the aluminium radiator.

Unfortunately, at this stage, dollars were a bit tight, the warranty had expired, and a new replacement rad was out of the question, so long story short, we kept the weeping radiator alive for several more years with “rislone”, a special coolant additive for weeping aluminium radiators, this stuff actually works, and was the best solution under the circumstances at the time.

But of course, the radiator did ultimately totally fail, and the decision had to be made again.
Aluminium or NOT?
Not wanting to give up on the idea of an aluminium radiator, the decision was made to tackle the project again… and commission PWR to build Aluminium Rad #2.

You might think I’m a sucker for bling that fails. Yes, having an expensive product fail is not much fun, but failures happen for a reason, but the hard part is not knowing what the actual cause was. So for the second time around, we followed the instructions and guidelines to the letter… new red coolant, fresh distilled water, a thorough flush and clean of the cooling system. Thorough checks, and double checks for stray current… which indicated well below the limits set out in PWR install instructions. We documented, took photographs, and shot short videos, just to back up how the install process was carried out.

So, long story short, at about the ninth month after installation, the second radiator also failed. Not happy Jan, as the old Aussie TV advert goes.

The photo above illustrates the test probe required to test for stray current. The probe is inserted through the filler cap of the surge tank and fed through the upper hose and into the side header tank of the cross flow radiator.

Note the plastic shroud to protect the copper wire loop…. the wire of the probe Must NOT touch the metal of the radiator. To carry out the test, one lead of the test meter is earthed, the other is connected to the bare copper of the probe, and you hope that the reading is less than 0.05 Milliamps. If not, we’ve got a problem Houston.

This is what you don’t want to happen with your expensive aluminium radiator. The cause of this was both baffling to the writer, and also to PWR, who requested that the radiator be shipped back for internal inspection.

After the first weep indicator was visible, a very close eye was kept on things, with accurate log book notes (And photographs) kept of the progress.

Finally, the radiator was drained, removed, and packed into the original shipping box and returned to PWR for inspection. But before it was shipped, I took close up photos of the internal metal (Through the necks, top and bottom) which was still bright and clean, just like new aluminium, so I was confident that the problem was not attributed to stray current…

So what could it be?

It took a while to get an answer from PWR, naturally I was keen to hear from them to what exactly was going on. So finally after a bit of hassling via phone calls, after about three weeks, the technical consultant put it down to a production line problem which caused the failure… Phew, that was a relief, and then I was told that it would be covered under warranty, more good mews! The rad failed after about nine or ten months, and stray current was not to blame in this case.

It took another four weeks before the replacement rad was built and shipped. The installation procedure (Checking for stray current) was still required to be carried out, which we did, and the result was same as previous… which was well below the stated recommendations.

This has been quite a journey. (Many years in fact) And in hindsight, if I knew then, what I know now, I may not have ventured down this path. I still love the look of polished aluminium radiators, and they are great for keeping a high performance engine cool, but unfortunately, they can be prone to premature failure.
I am hoping that the existing radiator will keep performing as expected, but if it fails again… That’s it, we will revert back to the brass/copper style again… but it would still need to of cross flow format.

In closing, I understand that there are many people out there who have had zero problems with aluminium radiators, if you’re one of them, congratulations, I hope that you continue to have a good run.
But there can be issues, which can cause many frustrations, so if you are thinking of going down this road, have a good hard think about it before you take the leap.

Note: PWR performance are well established in Australia and on the international scene, we were pleased with the way that PWR handled the situation and the attention and support they provided. ‘You can’t ask anymore than that.‘
One of the inherent problems with aluminium rads is where the core tubes are brazed into the header tanks, the joints are rice paper thin, and are brazed or soldered using a highly sophisticated process. This particular problem does not occur with brass/copper rads because of the more substantial old school solder process that has always been used.

After a period of time now since the third radiator replacement has failed, now is the time for some automotive truth telling. This is the third aluminium radiator replacement in about ten years. Every replacement radiator has failed in the same spot. While they look great, are excellent heat exchanger’s or cooling devices, but the reliability factor is extremely poor, they are not cheap, and in reality, probably not great value when it comes to longevity. In the near future we will be looking for someone to build a cross flow copper/brass radiator.