The exhaust manifold is leaking from only the rear cylinder. A shop told me this is about an 8 hour job as they have to take so much apart. I notice that the manifold is one piece for the center 4 cylinders, but the front and rear are separate pieces. Is there any way that they could replace just the rear gasket? Or with 400K miles on the engine, are those pieces pretty much welded together now?

 

Saw a mechanic doing one last week, 450k miles on the truck. The problem with doing just one is that you disturb the other gaskets as you have to loosen off all the bolts to get the leaking one out. Do them all...better safe than sorry.

8 hours sounds like a bit of overkill, I'm not doing the job but taking off a turbo and bit of other stuff to expose an exhaust manifold doesn't take that long.

 

Thanks mgfg. If they're removing the entire manifold then of course they would replace all the gaskets. I was wondering if the one end of the manifold could be slid off without touching the rest of it, but most likely not. If you could get it apart, it would probably be impossible to put together and keep a new gasket from getting damaged.

The 8 hours was quickly off the top of his head, maybe just to scare me a bit. I was thinking the same thing (8 hours?)

 

Might be more hours if a few studs decide they don't want to leave the head.

 

Seems like it's usually been about $800-$1000 when I've had it done.

 

My truck (’06 Pete 387 with 450 ISX) has this problem. I had a loud squealing that was eventually diagnosed as a leaking exhaust manifold gasket. One or more of the bolts had broken and the Peterbilt dealer just north of Louisville charged me about $500 to replace the bolts and gasket.

A year and three months later the problem recurred and my local Cummins dealer (Vernell’s in Marion, IL) charged me about $400 to replace all the bolts (one had already broken and three more broke while they were trying to remove them) and the gasket. The service manager Don Bronson, at Vernell’s said this is a very common problem. Apparently the design of the exhaust and turbo system does not allow for enough support for the turbo assembly and that in turn places too much pressure on the manifold itself. Since the back-most exhaust port is its own separate piece and only held by one upper and one lower bolt, it is the weakest link in the whole assembly and therefore is the most likely to break.

 

As it turns out, it wasn't the back cylinder anyways. It was the back side of the 2nd from back blowing black all over the back one. I'm not a mechanic but crazy me decided I would try to do this myself. I first loosened all bolts just a bit to make sure none would break or were broken. If any were I'd quit there.

Musicman's comment about a loud squealing is scaring me. I have a squeal now that I hear, my wife doesn't though and I thought her hearing is better than mine. Maybe I didn't torque something enough?

Hopefully this trip goes well.