Workshop: Fabric Hood Revival

Keeping your car’s radiator and all the associated pumbing clean will pay dividends when the hot weather returns.

A shabby fabric soft top will spoil the look of your classic roadster. We show how to smarten one up and make it waterproof.

T he water in your cooling system is a medium for transferring heat – it goes from the engine to the water as it flows through the block and head and then from water to air as the coolant passes through the radiator before repeating the process. Keeping this system at its optimum efficiency relies on two things – the heat being able to transfer to and from the water as required and the water being able to flow as it’s supposed to. Regularly flushing of the system is key to maintaining both these abilities.

In fact the water in your cooling system is its own worst enemy. If your block is iron it will cause it to rust, allowing rust flakes to build up in the cooling galleries and clog the radiator tubes. Unless you (and all your car’s previous owners) have been fastidious about using distilled water then scale will gradually build up on all the internal surfaces of the water galleries and radiator, effectively acting as an insulator – just one 1/64 of an inch of scale in the cylinder head can decrease the efficiency of the cooling system by as much as 25 per cent. And over the decades the inevitable bits of dirt and grime that get into the water and the loose rust flakes and scale, build up in unwelcome corners, obstructing the flow.

The anti-freeze you mix with the water has corrosion inhibitors to keep these problems to a minimum but these additives lose their abilities over time, which is why you should regularly change your coolant. But there’s little point in putting clean coolant into a dirty cooling system so you should flush out the system each time. And if this has been neglected, you may well need to do a flush to remove many years’ worth of grot and help your car keep its cool!

As you can tell from the variety of cars in the illustrations, the procedure is largely the same for cars of all sorts and layouts.