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Happy New Leak

Happy New Year, everyone! I trust your festive season has been filled with joy and inspiration, setting the tone for a wonderful 2024 ahead.


I happened to venture into my garage and noticed a sight all too familiar—a small pool of coolant beneath the nose cone of a Caterham Seven, signalling yet another potential radiator failure! This time, the telltale droplets were not beneath the 420R, providing a sigh of relief. I've already replaced the radiator on the 420R a total of 4 times. It now appears to be the turn of the 620R.


Caterham Cars leaking radiator
Evidence of a leaking radiator

Having grown accustomed to this issue, I'd previously acquired an inexpensive cooling system pressure test kit. These kits prove incredibly useful, allowing you to assess a coolant system without the need to heat everything up, which for a home mechanic, can be both inconvenient and potentially bothersome to neighbours.


Amazon Coolant test kit
Coolant test kit

Subsequently, I removed the nose cone and bonnet, securing the test kit to the coolant expansion tank. I applied 10 psi of pressure through the kit's hand pump and left the 620R undisturbed for a couple of days. The expectation was that the heightened pressure would enhance the flow from the initially sluggish rate observed under normal atmospheric conditions.



Returning to the 620R some days later has confirmed the inevitable, a very small leak half way down the offside end tank.


Having performed the pressure test and confirmed the location of a leak, the conclusion is clear, a new radiator is needed. The hunt is on.


Caterham Cars offers a replacement unit through their parts website. I've included a link to the part below.



The radiator is exclusively available with the attached oil cooler, rendering the replacement of a failed radiator a relatively costly option. Considering this, and the frequency of general failures I've started looking at alternatives.


Many Caterham owners consider Radtec radiators to be a fantastic alternative providing a quality product with much improve longevity. Reviewing the Radtec website confirms a 620R replacement radiator is available with or without the attached oil cooler. At this point it's unclear if the Radtec radiator is compatible with the Caterham Cars oil cooler. A complete Radtec kit might therefore be required. If they are not compatible, investing in the Radtec ecosystem is still considered beneficial as any future failures could leverage their more modular approach.


Today, I made the decision to order the Radtec kit and added it to my basket on their website. However, as I proceeded to process the order through their website checkout, it became apparent that the site was misconfigured for VAT on the Isle of Man, omitting the VAT from the transaction. I've dropped the team at Radtec an email and hope to resolve the matter soon, and proceed with the order. Watch this space.


Unable to complete the order, I took a few additional minutes to explore the rest of the website, driven by curiosity. During this exploration, I stumbled upon the following Coolant Advisory post.



Several fellow Caterham owners have suggested using a blue coolant as a potential solution to radiator failures. However, these recommendations have lacked supporting evidence. While I value input from fellow owners, the aforementioned advisory adds substantial weight to the justification for considering a coolant type switch. I intend to conduct further research on the matter before making any changes. If it is confirmed that the Ford Duratec engine is compatible with blue coolant, I will ensure that the new radiator is supplied with this specific coolant.


I'll post any interesting findings associated with coolant compatibility and of course a full post on replacing the radiator, hopefully with a Radtec kit!



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