I had noticed that it always seemed to be the rear two cylinders that overheated, the front were always OK. I was talking about this to an old friend when he mentioned a problem he had had with an old Mini engine. The rear core plug had corroded and deposited debris around the rear piston liner, effectively blocking it. This was confirmed as a common problem by Bob from Daventry at last months Bug meeting.

Bob advised me to remove the rear drain plug and scrape out the rear of the block with a piece of copper wire. Having completed this somewhat awkward but very easy task, and flushed the engine yet again, the overheating problem has now been resolved. In fact the engine now hardly ever gets above normal.

I hope this tip helps others who are experiencing similar problems.