MISSING THE POINT
QMy Mini 1275GT runs quite rough and the temperature gauge swings around wildly. I filled it with waterless coolant, which has solved an occasional boiling problem – but the roughness persists. Any ideas? Dirk Vierdag, Amsterdam
ADon’t try to use waterless coolant as a mechanical sticking plaster. It will allow a faulty engine to overheat damagingly – way past the point where a cloud of steam would usually force you to stop. Make absolutely sure your engine is in perfect health before putting it in… or simply don’t put it in at all.
It sounds as though you have a head gasket problem. It’s probably blown between two cylinders – hence the rough running – and it’s also leaking gases into the cooling system.
First, do a compression test. With the engine hot, unscrew the spark plugs and put the tester into each hole in turn. Spin the engine on the starter with the throttle held open and observe the reading on the gauge after a few seconds. If two adjacent cylinders have a reading much below the other two, this would confirm that the head gasket is leaking between them. Also, sniff the coolant expansion tank.
Does it smell of petrol, oil or exhaust fumes? This implies the head gasket is leaking into the cooling system.
Be sure to fit a good quality replacement gasket. Make sure the mating surfaces of the cylinderhead and block are perfectly smooth and flat. If the problem persists, have the head checked for cracks by an engineering shop.