I have a 1993 5.8l and I noticed that the port side exhaust manifold and riser was getting (what I felt) too hot. I took the hose off of the thermostat housing and stuck the garden hose on it, sure enough, No water is getting through that side. I am guessing that corrosion and rust are blocking the water passage and I was wondering if there is a way I can clean this out effectively or if I need to buy a new exhaust manifold.