Here you get all information about the care and maintenance of your Böhm Stirling engines.

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Maintenance - piston cleaning on Stirling engine

Over time, black abrasion dust builds up in the friction bearing (piston/cylinder) which settles in the cylinder and makes the model run more poorly even resulting in a standstill. You must therefore (after 1-2 hours battery life) regularly clean the inside of piston and cylinder on the sliding surfaces. Scoring is normal (friction bearing).

Remove the piston and clean the piston and working cylinder with a dry cloth. Clean the brass cylinder inside down to the bottom. Reassemble dry WITHOUT lubricant. See photos for better understanding.

Basically, Stirling engines are to be kept oil-free with working pistons