As you may have read, the Caterham does occasionally loose its coolant… and the K-series engine has a reputation for blowing head-gaskets if allowed to overheat…
So after a fabulous day blatting round Wiltshire, Oxfordshire, Berkshire – making the Ashbury Triangle video (https://youtu.be/i5vv2FJk02A) – I arrived home to find my car dropping what was left of its coolant on the garage floor. The expansion bottle was empty… oh sh*t.
It had run great all day, not getting over 80°c and the fan kicking in as needed… but now there were small puddles on the floor. I had had a look underneath with a torch and squeezed all the (still hot) hoses, but the big puzzle is everything looks dry and firmly attached. The only damp-looking areas are the down near the sump, above the oil pressure sender – the low 'v' shaped black line – and the distributor cap and HT Leads seem to have spray / condensation on them…? No sign of any oil/water mix under the oil filler cap. All clean. Phew!
The puddle locations suggested front of engine, and possibly radiator… but I had foolishly moved the car back to get a better look. Doh!
So, do I refill and test for leaks in the garage, or is this a more serious issue that needs professional help before I risk running the engine again?
After a few discussions online with more knowledgeable Caterham owners, and poking about in the engine bay some more, I located the source of the leak – the heater hose was wet and perished / split. This would tie-in with the spray residual on the camcover and distributor cap. New hose needed. The internet forums agreed that a new hose was the best solution, and as one hose failing could indicate that the rest are also close to end-of-life, I ordered a complete new set of hoses from SFS (www.siliconhose.com) which is based not far from me… this worked out rather well, as David, director from SFS personally delivered my replacement hoses and clips on his way home one evening. Top bloke, and the shiny hoses looked great. Now the fitting marathon started.
Actually it wasn't that bad. By removing each of the old hoses one-by-one, and fitting the matching-shape new hose in the vacated spot, I kept the confusion to the minimum. Some went on easy, others did not, but it was a quality garage session and I learned a lot about the Caterham is put together. Hoses on, time to refill the system, bleed (I had done that before once) and then test. With the new coolant added, and the front of the car raised as high as possible to encourage the air out, I began the warming process. Hmmmm. This was not going to plan. The bleed screw / nut on my radiator does not have any kind of washer. When I tried and tighten it, the thread stops but the nut still rotates in the hole. It wiggles up and down. Not a good seal. Should there be a washer here? If so, what kind / material? My investigations turned up a number of unsuccessful solutions, and after a few days of going in circles I rang Rob at Ratrace who services the car – we agreed that driving the car to him without a sealed radiator was a BAD IDEA – and then he suggested I remove the radiator and bring it over… genius! Drain the coolant (again), unbolt the radiator, pack it in the family car and head over to Potters Bar. After about 30 minutes of felting, Rob had cut a new thread in the aluminium radiator, found a bolt to fit, and added a bonded washer to seal the hole. Legend! Reassembled and refilled with coolant I could now drive the car again, and give the new silicone pipework a proper test. All is running well.