Morris Minor Owners Club

what is the cause of the white mayonese on the oil filler cap.
van has done short trips only, but was supposed to be a recon engine ??????

You have answered your own question, the mayonnaise is usually the result of many short runs where the engine does not reach its top temperature for long enough to evaporate the condensation etc. Having said that, the Minor in particular seems to suffer from this even if there is nothing wrong with the engine (BLOWN HEAD GASKET). I had two minors at the same time, used under the same conditions, and one always produced mayonnaise, the other never did! If you give the engine some regular blasts down the motorway you should eventually see an end to the problem.

Thank you willie

You can also put in a higher temperature thermostat - 88deg or 92 deg so the engine runs hotter - as per MMOC tech tips - it worked for me.

Rog

High temp stat is great in winter - I wouldn't do this in summer. Good breather connections (one directly to the carb) and a good hard run each week should sort it out.

I have also found that some types of oil are more prone to it than others for example Duckhams was far worse than Castrol and I can only put it down to the different specs of the oils.

My recon engine initially did this too, but now is perfectly OK.