jeepjones

When I bought my TJ it had a small crack in the oem exhaust manifold which soon turned into a major crack, I considered this a normal "Jeep Thing" and replaced them
with a 409 Stainless header made by Rugged Ridge. Everything was great until 2 weeks ago when I noticed that cracked header sound after a wheeling trip. Now my questions are: Is this normal to have to replace the headers every year? Are the rugged Ridge Headers Crap? Would worn out motor mounts have anything to do with this (too much movement)? Or is there anything I can do to the Rigid jeep exhaust system to free up some flex room when the engine is being torqued? I'll be going with the Banks Torque Tubes next cause they seem to be the beefiest headers
I've seen for the Jeep. Any help would be greatly appreciated, thanks.

oldfart

It's not uncommon for the factory headers to crack. There have been a few different design changes over the years and sometimes they will still crack. I will make a suggestion, enlarge the holes slightly in the headers where they attach to the head, weld up the cracks, replace the gaskets and bolt them back on being very careful to observe the torque figures.

jeepjones

Im not talking about the factory exhaust manifolds, please reread my post.

Savasa

JJ,
If you've noticed, stock headers seem to crack BESIDE the weld, not on the weld itself. The very act of welding changes the crystaline structure of the metal and thus weakens it. Many, many years ago I was told (buy a fellow that raced stock cars and built his own engines) that stainless tends to get brittle and will crack more readily than plain steel headers.
Don't know what to tell you about YOUR particular situation but if you replace your stainless set-up, you MAY get better service with regular steel headers. After all, I think the only reason to go with stainless is to eliminate rust. I don't think they (SS) flow any better than non SS and how much can regular steel rust to the point of failure? As I've said, stock header failure seems to be from cracking as opposed to rusting.
Peter

04WJGuy

Hi jeepjones,
you didn't say which motor this is happening on but drop Nick at kolak@aol.com an e-mail and he should be able to help you sort out the problem. The 4.0L headers were prone to cracking, stock and aftermarket. I bought a Doug Thorley header for mine and haven't had any problems since.

oldfart

The reason they crack is due the difference in the coefeciance of expansion between the three foot long cast iron engine and the headers, stock or otherwise, hence my suggestion for a solution. Why do I even bother trying to explain this stuff?

04WJGuy

Don't let it get you down oldfart, it's a good temp fix. The only problem I've found with the 4.0 is that the header tends to crack on either side of the weld after unless you have some way of doing some post heat treatment on it and I don't know about you but the ex used to hate finding me using her oven to do slow cool downs on parts.

RiponredTJ

Get yourself some headers with expansion joints. Everything I've ever read about this common problem indicates that's the best solution.

http://dailydriventj.com/forum/viewtopic.php?t=847

jeepjones

Well guys I've found that the motor mounts are worn which doesn't help the situation and probably contributed to the tubes cracking just above the welds at the collector. The engine is doing some serious sideways movement when it is under torque either way new header and poly motor mounts going in. Welding the cracked tube will just lead to another cracked tube and a major pain in the ***.

Sid1966

adding one or two extra exhaust hangers may help there is a lot of pipe hanging off the jeep, ,the factory hanger is at the cat leaving about 6 feet of pipe unsupported where it wraps around the motor.