Recently i have just fitted a 1300 marina engine and have done a number of miles in it. it is fitted with ally rocker cover and 3 branch manifold and twin 1" 1/4 su. The past few times i have been out in it i have had like mulsh of white/brown slush at the top of my oil filler cap. I went up to hampshire friday in it and had no problems what so ever and felt no lack of power or saw no visual smoke. When back at home checking car over and there is a slush inside the oil filler cap and sitting inside the rocker cover it was there but there was nothing up the side of the dipstick and no visual loss of water and no sign of oil in the water. Has my head gasket gone? or am i missing something?
Any help would be great

Loz