Ur going to have to tell us if its a crack because I cant say for sure by looking ay pics

 

i kind of see what might be a crack right at the "Y". My jeep sounds like that too only louder. It's driving me nuts

 

One would assume that if the exhaust is cracked you would see at least some discoloration of the area from the leaking exhaust gases. Could be wrong just throwing it out there.

 

Try putting some soapy water on it and start it up. Should be able to tell if you see little bubles being made.

 

you cant see it in the pic but that area is a little bit whiter but good call on the soapy water, ill try that in the morning

 

I say yes, thats the common place for them to crack, where the tubes meet the collector

 

That looks like every other picture I've seen (and the real deal after I replaced my own) of the infamous 4.0L exhaust manifold crack!

Congratulations on the Jeep

 

Would a small crack like that cause a loss in mpg or any other negative effects?

 

Probably not

 

Yes: What happens is exhaust fumes are escaping through this hole creating a noise and a smell. Since the full exhaust stream no longer runs past the O2 sensor, as far as it can tell the engine is running lean, so it dumps more fuel in.

When I got my manifold replaced I thought something was wrong. I was so used to not having to hit the throttle at all to shift into gear... before, it was running so rich that I could pretty much dump the clutch and off I went. Cost me a hell of a lot in gas money

 

What are good cost efficient aftermarket exhaust manifold options?

 

I heard something about the 4.0's being notorious for a poor fitting prison wrist pin that would start knocking after they got some miles on them...nothing critical...just annoying (so they say, I'd think a poor fitting wrist pin has the probability of breaking, but that's just me)

 

Well I found a guy to weld my exhaust manifold back for free on craigslist. I did give him $20 just to be nice and I got it back on just before it got to dark to see and cranked it up and well it's still ticking. Tomorrow I will see if maybe it;s the flex plate. Also it started smoking when I cranked it. Is that normal for a new gasket? Also I removed my injectors and now theyre kind of making a sucking noise, any ideas?

 

Weld won't last that long, if it worked, but for $20 I guess it's worth it lol. New headers and gaskets can indeed be expected to smoke, there's an oil residue left on them at the factory.

Regarding injectors.. what do you mean you removed them? While the engine was running? And fuel spilled everywhere and now the engine's sucking in air from an open hole? Or...