so i was replacing exaust manifold gasket and the bolt on the back of the block snapped off so that leaves me with 2 questions. First one is how hard is it to replace the bolt and two if i didnt replace it how bad of a leak would i have?

 

Replacing the bolt is easy. Getting the broken stub of the old one out...not so much.
Sometimes you luck out and there's enough left sticking out (after pulling the manifold) to get a wrench on, or weld a nut to.

It'll eventually leak.

 

what do i got to do? pull the block and drill it out?
or can i just weld a bolt on and bolt it on?

 

Weld a bolt on it, take it out, then get a new bolt altogether. You don't want to try and live without a bolt on the exhaust manifold. You'll have a bad time.

 

It would be helpful if you specified the model year and exactly which bolt you're talking about. But as far as I remember the last bolt, looking from the front, goes on a stud that is screwed into the head not the block. If you snapped the stud, then like others said, weld a nut and get it out. But I just can't see how you could get in there close enough to do it. Maybe I am missing something...Won't be the first time.

 

its a 87 jeep cherokee 4.0 and your saying weld a bolt on then pull the block out and put a new one in?

 

pull the block? The broken bolt is in the head, U can drill and use a easy out, or drill and retap. Either way bolt everything back up, run it to get the head hot, and then try to use the easy out. That heat really helps get the bolt to loosen up.

 

No...............they are saying, if there's enough of the stud/bolt sticking out, weld a nut onto the end of it so you can use a wrench to unscrew it out of the head.

If you don't have a welder however, there are other ways. Sears, as well as some auto parts stores, sell stud extractors that can be used to remove a stud or bolt shank with the head broken off of it.
You may even be able to rent one from your local auto parts store.

 

forsure i have an easy out and used them before its just theres no way i can get a drill in there so id have to pull the head off huh? damm more work and just did the oil pan

 

A right angle drill would get in there but, those things aren't exactly cheap.

 

Looks like the head will have to come of. Good time to replace the gasket.

 

And valve seals