Oil leaks

- by Brian Haines

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We all experience oil leaks some time in an Austin 7 engine’s life - after a rebuild or more generally after several miles usage.

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Oil seems to leak from places difficult to locate at times. First check the “core” plug above the oil pump drive gear and the sump to crankcase flange. In this case it’s always a good idea before fitting the sump casing to check that the flange is flat especially around the retaining bolt locations. One of the main sources of oil leak can often be between the block and crankcase.

On one of my engines the retaining studs have been replaced by cap screws screwed in from inside the crankcase giving the stud threads extra support from the cap head thus allowing the nuts to be tightened further without the possibility of stripping the aluminium thread. This does mean however that you have to face the area where the head of the cap screws locate. I seem to remember this was done by an ingenious cutter pulled upwards from the top face of the crankcase as you can’t access all these areas from inside the casing. If you do retain the existing studs make sure there are no raised sections where the studs enter the casing.

We have all tried various methods of curing this leak by using a new paper gasket suitably greased or by using all types of sealant with all that inevitable mess.

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A method tried very successfully over here in Western Australia is to use a thin silicon baking sheet used for placing in a cooking dish presumably to stop the pastry from sticking to the dish. No doubt it is obtainable in the UK from any cook-shop. Mark out the new gasket using the old as a pattern or the crankcase top face and punch and cut out the necessary areas. The outer sections can be trimmed off later using a sharp blade after the block has been tightened down.

Give it a try as you’ve nothing to lose, including your oil, and calling out a plumber later can be very expensive.


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