Joined: Jul 2020 Posts: 2 Threads: 1
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Location: UK
Car type: !927 Austin 7 Chummy
Thanks to all for these comments and suggestions. We think that the noise is much too loud to be ignition related, and that if it were a gudgeon pin problem there would be evidence in the bores. The crankshaft giving warning that it is on its way out seems most likely (since it is probably the original 1 1/8") and the engine is now going to come out for inspection and disassembly.
I will try to remember to update you with what we find.
Joined: Jan 2019 Posts: 1,481 Threads: 17
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Location: Bala North Wales
Car type: 1933 RP Standard Saloon
Don't be fooled into dismissing gudgeon pin wear just because there is no evidence on the side of the bore. That sort of damage only occurs if the clamping bolt fails and allows the pin to move side to side. On standard engines, the pin is firmly clamped inside the end of the connecting rod and it is the piston that provides the bearing surface. If there is any 'rock' between the piston and the gudgeon pin at all, it will make a noise.
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
It is difficult to imagine any engine fault not discernible with the sump off and all parts checked for rubbing bright spots, levered against for movement etc. Any gudgeon problem would show on every operating stroke and unlikely to resist hand cranking.
