Workshop Basics

How to keep your classic cool in summer and warm in winter

How to keep your classic cool.

Many classics are cooled by a thick soup of liquid rust. It looks grim and it doesn’t do the cooling system any good. Hoses build up such deposits that they crunch when squeezed. The same deposits coat the water channels of the cylinderhead and engine block, inhibiting heat transfer from the metal to the coolant. The narrow tubes of the radiator clog, too.

The thermostat can compensate for this for a while by opening further. As the problem gets worse, though, the maximum operating temperature will start to rise. Eventually, a fast run followed by traffic jam on a hot day will provoke an explosion of rusty minestrone from the radiator.

You’d think all this clag would helpfully seal leaks in the system, but it doesn’t. A low coolant level will lead to a disruption of correct flow and the formation of air pockets in critical areas of the cylinderhead. The mysterious onset of pinking when hot might be the first sign that things are awry. A hot head may also encourage fuel evaporation issues. Prevention is simply a matter of a good flushing, followed by an afternoon’s fiddling around to bring everything up to scratch. After this, the system should look after itself between its two-yearly changes of antifreeze.

This guide will show you what to do, what you’ll need and what you might find. Most cooling systems are straightforward to drain and refill, but do check your manual. Some have bleed valves that need to be opened to release air-locks.