I keep getting a black oil deposit on top of the water in my rad. 2.25 Series petrol. Very little water loss, but any water that is pumped out after a long hard run leaves a black oily deposit behind. Compressions fine (apart from the cylinder with a dodgy exhaust valve), no mayonaise in either sump, rocker or rad.
- Is it oil? It certainly looks like it, except when deposited by the overflow it ends up looking like a fine black powder deposit, untill you get in on your hands whence it behaves exactly like dried on oil
- Where the hell is it coming from? and if it is oil leaking into the water, why isn't there water in the oil as well?
Alex