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Why Are Radiators Kind Of Trash Now

Ford Festiva expelling steam from the radiator cap with the bonnet raised. Vehicle viewed from the front.

We all love a good radiator. That big chunky bit of aluminium or brass that acts as a giant heat sink for the entire engine, gearbox and (sometimes) the power steering. But are all radiators kind of trash now? And why can't you even repair radiators any more?

We start this story with Leo Hendrik Baekeland. In 1907 this 44 year young whipper snapper invented the first synthetic plastic known to mankind, Bakelite. With this invention, Dr Leo introduced what was a (seemingly) safe plastic compound into the world. A plastic that could be confidently used when exposed to heat, harsh environments, and even when faced with heavy solvents.

Dr Leo and his magic chemical puttered around leaching their way into everyday life right up until we start our story in the 70's.

In the 70s (when baby boomers were considered 'hip' and house prices were still in the 4 digits), the automobile was a bit simpler; cars were riveted together by big burly 'men' wearing overalls and ties, and the most advanced computer in any automobile was usually the radio.

Cars of this era were surprisingly expensive to manufacture as they required a lot of raw metals and manual labour in their construction. Because of this, manufacturers were constantly looking for ways to make cars cheaper to build.

See, car manufacturers of the time had been looking for a compound that had the material properties of Bakelite to use for things like radio knobs, distributor caps, and more. However, when they realised just how many boxes Bakelite ticked on a production level, it was basically open season.

First was interior pieces such as radio knobs, followed by dashboards and trims, and much more. At some stage in this journey of cost-cutting, some Dilbert put their hands up and suggested radiators as the next thing on the agenda.

Now, all throughout automotive history until this point, radiators were made of copper or brass. A metal that is mostly corrosion resistant, incredibly good at shedding heat, and is infinitely repairable and recyclable. A metal that is also incredibly expensive.

Sometime around the mid-late '70s, this genius of accounting and engineering realised that by using an aluminium radiator core capped with Bakelite (plastic) end tanks, they could save 34c per vehicle, and thus the plastic capped radiator was born.

Now, is there anything inherently wrong with the plastic cap radiator? No! It's a great invention and would have been a big leap forward for the time.

So what is the issue with plastic radiator tanks?

Here's the thing, as time goes on these radiators were exposed to repetitive heat cycling and pressure build-ups, exactly as they should be. However, if you've ever left a takeaway container out in the sun for a few weeks, you'll understand that this leaves plastic extremely brittle and weakened.

On top of this, the new plastic end tanks couldn't be secured with brazing (a type of metal joining similar to welding) which meant they were now crimped (clamped) on with a little rubber gasket which is also prone to failure of the same method.

As time went on, these radiators and seals quickly became more and more brittle and eventually would leak, split or burst entirely.

In all honesty, brass radiators weren't without fault either. They too could burst or leak or corrode, but they could also be repaired or completely recycled, a stark contrast to their plastic replacement.

How long does a modern, plastic radiator last then?

It's hard to say as every car is going to be slightly different however, a normal life span is probably around 10 years. At least they're cheap to replace now.


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