What's this filth in my rocker cover?

[pictonroad]

This stuff was blocking 80% of the breather(?) on top of the rocker cover, I've chipped the edge of it it but it's bloomin hard, it's black and honeycomb brown underneath??

[danman2k]

i started a thread same as you have done, its for the breather pipe to the throttle body. condensation builds up and leaves this mess. its from short journeys and not letting the engine heat up normally. its perfectly fine. give it a clean with carb cleaner and the remove the breather pipe too and clean that. mine was bunged up terrible. car was lovely after.