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We were travelling back from holiday recently and after approximately 3 hours of driving found the engine was losing power.

Upon lifting the bonnet we discovered the radiator cap was missing. The temperature gauge was in the red, but the engine itself did not feel too hot. We had checked the radiator water level the week before and had travelled about 1,000kms since then.

It now looks like the engine needs a major repair. Do you have any suggestions was how this could have happened?

John

From the "Ask Jack" archives - 7 September 2009

The cause of the overheating was obviously the fact the radiator cap was missing.

A radiator cap does not come lose by itself from my experience and I would suspect that when the water level was checked the week prior to the engine overheating, the cap has not been refitted correctly. The fact the car travelled the distance it did before finally expiring is difficult to answer but possibly partial pressure was enough to stop a quicker major overheat. Or short driving spells may have been enough to stop the engine overheating fully.

It sounds like a very expensive repair.