Well I have aquired a Standard 23 C Diesel engine which I intend to rebuild. The engine has been stood with the head off for the last 15 years so cylinder bores are very heavily rusted. The liquid you can see is Plusgas. I am sorely tempted to fill the bores with citric acid to dissolve the rust (What do you guys think) to make piston removal easier. Once I have the pistons out the plan is to pull and replace the liners and pistons as part of the complete overhaul. The 23c engine was notoriously bad to start so attention to detail especially with the timing will be paramount.