Is it possible for the exhaust manifold gasket to rot?
Reason being i can hear what sounds like my exhaust blowing, i've climbed underneath it and not found a leak anywhere. It sounds loudest when i got the bonnet open. My rocker cover gasket leaks oil so i'm wondering if it may have rotted the gasket and made it leak hence the blowing. I've not taken the heatshield off yet to check but thought i'd ask.