Mayonnaise under the oil filler cap...

The blokes on Deals on Wheels would say it was a sure sign of a blown head gasket.

I am hoping it is something far easier to fix.

I noticed the water temp rise above normal while driving my B20 Amazon. It does not seem to have lost any water but there is the tell-tale mayo under the oil filler cap and a drop in power.

Has anyone had this happen and found it not to be the head gasket?

jools

[Mike Arnold]

I had this mildly in an old engine on my 122. I believe that it was due to blow-by on the rings pushing exhaust gases (including water vapour) into the crankcase which then emulsified with the oil to produce mayo. I know that it had some crankcase compression because of the quantity of oil that was blown out of the vent pipe.

Eventually, I replaced the engine and have not had any repeat.