CHUMMY CRANKCASE TO BLOCK GASKET

Oil leaks at the block base gasket, between block and crankcase, are a very common issue as aluminium meets cast iron. First make sure the leak is not coming from the front camshaft fixing or the tappet cover seal.
I changed a block base gasket for a customer this week and fitted one of the Seven Workshop modern silicone gaskets (dry). The consensus is that they are quite effective.

It is possible to do it with the engine in although the block is really close to the bulkhead on a Chummy. Remove the spark plugs and dynamo housing, to access front fixing. Remove the starter mounting from the crankcase to access the rear stud and undo the rest. Remove the manifold to front pipe nuts and carb sundries. Drain the radiator and remove the hoses.

Underneath, drain the oil and remove the sump and gauze. Carefully mark all big ends. All caps must go back the same way round and on the correct rod. Unbolt the big ends and lift the entire top end of the engine up and away, trying to keep the pistons in bores. (I never fit ‘cocoa tins’). Thorough-ly clean and degrease then reassemble all, set the tappets and retime the ignition.

Gary Munn DA7C