exhaust manifold

what does an exhaust manifold do? how important is it to your motor? and should it be replaced asap

 

as long as you don't have any check engine lights and don't feel carbon monoxide poisoning in the cab then you don't "have to" replace it and the engine will just be a little louder because of the crack in it

if and when you do replace it use the new and improved design stock header manifold from the 2002 to 2004 trucks because its steel and not heavy cast iron. this saves weight and eliminates the repeating cracks you see in those newer cast manifolds after only 2 or 3 years

 

The check engine light is on for the cat conv.

 

hmm, then it might be leaking enough to require you change it then but I would first reset the light and see if it comes back on again

 

does it hurt my motor running it with one thats leaks?