gary0003 Posted January 3, 2022 Share Posted January 3, 2022 Can anyone offer me some advice as to how best to free a seized piston from a 1939 Velocette MOV please. The piston is still connected to the conrod which is connected to the crankshaft via a rusty/seized big end! Thanks Gary. Quote Link to comment Share on other sites More sharing options...
jenkinov Posted January 4, 2022 Share Posted January 4, 2022 Hi .It's first beneficial to understand why the engine seized ...has it seized due to a component failure or has it been stood a log time and the piston rings have corroded and attached themselves to The cylinder wall. Let's assume there's no evidential damage and it's just seized with age and corrosion I would start by dumping it all in a bucket of paraffin or Diesel .whilst it may sound expensive servicing garages often have lots of spoilt fuel from miss fuelling .. They often have 20litre containers for oil and cleaning fluids.these will importantly be fuel proof. I would pop around a few garages with a box of quality street and you should get sorted.. Get the engine into this and give it a long soak ......after a week remove it and clean anything you can get to with brushes/wire wool . Then apply penetrating oil as required... This process repeated should allow you to identify the extent of the corrosion and whether the items are salvageable or just scrap .please share some photos ... Jenkinov 2 Quote Link to comment Share on other sites More sharing options...
G506 Posted February 4, 2022 Share Posted February 4, 2022 Diesel and paraffin are both good, but personally I use coca cola. I once managed to free up a bore seized truck engine this way. Full fat, freshly opened Coke, genuine not supermarket own brand, cram as much as you possibly can into the cylinder, and wait. Maybe a few minutes or a few hours. If theres no movement, empty and repeat with another freshly opened can or bottle and try again. A lot of people clean old coins with Coke, and the same basic principle applies here. Quote Link to comment Share on other sites More sharing options...
ruxy Posted February 4, 2022 Share Posted February 4, 2022 Diesel is OK , white vinegar is probably more aggressive than coke - OK for some things. Don't use kerosene/28 sec. burning oil because it is hygroscopic - so steel will rust and also some grades of cast iron. paraffin is very near to kero - so I would expect the same results , try some bright nails or an old bearing overnight Quote Link to comment Share on other sites More sharing options...
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