You hear lots of questions on various message boards regarding cars overheating in the summer especially in heavy traffic and people having to fit Kenlowe fans to cure the problem. Personally I have never had any problems with over heating on both my classics (MGBGT and Triumph Spitfire IV) they have both managed to keep their cool whatever the weather or traffic. This is more than likely due to regular maintenance rather than pure luck. When I bought my classics one of the first jobs I did was to replace the water hoses as I did not know how long they had been on the car and did not want to be stranded with a split hose and no water.
This is a quick, cheap and simple job which will improve the reliability of your classic. Including the costs of the clips a full set of hoses cost me around £30 for each car as were fitted in a couple of hours. While you are doing this it is a great opportunity to flush your radiator and engine block. It is a good idea to do this every 12 months especially if the car is laid up over the winter, where the radiator should not be drained but back flushed and recharged with clean water and good quality corrosion inhibiting antifreeze once the car is brought out of hibernation.
To back flush the radiator it is best to carefully remove it from the car and lightly brush both sides of the core using an old scrubbing brush (do not use a wire brush as they will cause damage to the radiator). Use either an air line or water hose to blast out any debris from within the core. Turn the radiator upside down so that water can be hosed in a reverse direction to normal flow. Let the water run through until the water running out become clean. The radiator can now be checked for damage and any repainting of the header or footer tanks can be done but avoiding painting the core if possible otherwise thermal efficiency will be lost.
The engine block and heater system of the car can also be flushed at the same time by connecting a water hose to various hoses, make sure that the heater valve is open so that the water can flow through the heater matrix. Again make sure the water runs clean before moving onto the next hose.
Check all hoses for cracks or damage but if in any doubt it is best to change them and also check the radiator cap seal for damage.
After a run in the dales I noticed that the water level in the BGT had dropped but this could have been normal as the B does not have an expansion tank so that any extra water in the system is pushed overboard. Over the next few days the water level kept dropping even though I was topping up and there were signs of water stains on the core. I decided to fit a new radiator so ordered one from the MGOC which was a good price and the delivery was quick.
Removing the old radiator was easy and was soon out of the way. Before I installed the new radiator I re-tapped out the holes in the radiator as they had been painted. I also redid the threads of the bolts which hold the radiator into the car, this made the reassembly much easier
Getting the bottom hose on however was a real pain as access is very limited and it needs a bit of force to get the hose on and it took 3 attempts and a new hose clip before I finally got it to seal.
I then half filled the radiator with water and topped it up with antifreeze with corrosion inhibitor. I ran the engine until hot enough for the thermostat to open and left to cool before checking the level of the water again and final topping up. It is a good idea to keep a premixed solution of water and antifreeze for topping up throughout the coming year.
Even though the BGT never ran hot the temperature needle always was on the N (Normal) but after changing the radiator the reading of the gauge was slightly less so even though I had back flushed the radiator 12 months previous it must have been slightly corroded internally and not a thermally efficient as the new radiator.