Cracked turbo exhaust outlet tube

[samert]

On my 1996 American Tradition with 8.3L the turbo exhaust outlet tube has cracked twice now rendering the exhaust brake ineffective. This is a Cummins supplied part on the Spartan IC-2242 chassis. This outlet tube has a rib formed in it I suspect to allow it to expand and contract but this is where it always seems to crack. Just wondering if anyone else has had to deal with this issue and what did you change to keep it from happening again? I was thinking of cutting out a section of pipe and adding some flex pipe to help absorb some of the stresses this pipe sees but there is not a lot of pipe to work with.



Here is a photo of the latest repair where I had the cracked welded from the inside where the rib forms a nice valley to fill in with weld. The crack is in the rib just to the right of the clamp.



Here is a photo of the entire pipe from the turbo to the exhaust brake. Note the 2 clamps that hold the pipe in place. They are bolted directly to the exhaust manifold so it's held pretty rigid.

[samert]

Just drove it 750 miles in the last 2 days. No problems so far.

[samert]

NinerBikes wrote:
How old or new are your engine mounts, and are they a wear item? Too much flex in the engine mounts can stress exhaust systems beyond their design capabilities.

As far as I know they are original. However, the 2 brackets supporting the pipe assembly are bolted directly the exhaust manifold as is the turbo so that entire assemble is held rigid to the engine and any torque movement from the engine, these components just move with it. There is flex pipe after the exhaust brake down to the muffler to absorb any movement from the engine.

[MEXICOWANDERER]

This is obviously a thermal stress issue. What some of you are saying is that a VIBRASORBER type interface connector cannot work here? This is a learning question and not a statement...

[_40Fan]

samert wrote:

Bull Rider wrote:
I do hobby welding. I have a TIG welder and a MIG welder. I TIG weld stainless steel. There are a TON of different types of stainless steel, and a TON of different types of filler wire. Some of it is very specialized.

If you want quality input from people that know everything to know about welding, post your question and photos over at Weldingweb.com

The guys/gals over at Weldingweb are very helpful, but can be colorful and harsh too, just so you know in advance.

Also provide information on who welded it in the past, and any other photos. Include clear close up photos of the weld.

You will get an answer, probably more than you need.

My original description may have been a little confusing. The last time it cracked (2008) I cut out and replaced the tube coming off the turbo. Then I noticed (last Sunday) it had cracked again, same place as last time. I couldn't get a new tube in time for my upcoming trip, plus if I keep cutting out the old I will run out of length on the pipe it's welded to. So I had the maintenance welder at work repair the crack by welding it on the inside of the pipe filling in the rib where it seems to crack. I put a jamb nut inside the saddle on the clamps so I could leave them a little loose on the pipe this time to allow it to expand & contract but still support the assembly. Hopefully it will hold up this time.

Exactly what I would have done. I bet it will hold up.

[NinerBikes]

How old or new are your engine mounts, and are they a wear item? Too much flex in the engine mounts can stress exhaust systems beyond their design capabilities.

[samert]

Bull Rider wrote:
I do hobby welding. I have a TIG welder and a MIG welder. I TIG weld stainless steel. There are a TON of different types of stainless steel, and a TON of different types of filler wire. Some of it is very specialized.

If you want quality input from people that know everything to know about welding, post your question and photos over at Weldingweb.com

The guys/gals over at Weldingweb are very helpful, but can be colorful and harsh too, just so you know in advance.

Also provide information on who welded it in the past, and any other photos. Include clear close up photos of the weld.

You will get an answer, probably more than you need.

My original description may have been a little confusing. The last time it cracked (2008) I cut out and replaced the tube coming off the turbo. Then I noticed (last Sunday) it had cracked again, same place as last time. I couldn't get a new tube in time for my upcoming trip, plus if I keep cutting out the old I will run out of length on the pipe it's welded to. So I had the maintenance welder at work repair the crack by welding it on the inside of the pipe filling in the rib where it seems to crack. I put a jamb nut inside the saddle on the clamps so I could leave them a little loose on the pipe this time to allow it to expand & contract but still support the assembly. Hopefully it will hold up this time.

[Bull_Rider]

I do hobby welding. I have a TIG welder and a MIG welder. I TIG weld stainless steel. There are a TON of different types of stainless steel, and a TON of different types of filler wire. Some of it is very specialized.

If you want quality input from people that know everything to know about welding, post your question and photos over at Weldingweb.com

The guys/gals over at Weldingweb are very helpful, but can be colorful and harsh too, just so you know in advance.

Also provide information on who welded it in the past, and any other photos. Include clear close up photos of the weld.

You will get an answer, probably more than you need.

[samert]

teddychamp wrote:
The original pipe from Cummins with the rib is designed to prevent the cracking of the pipe. HOW Ever the Key to the problem is, that you must let the Engine run 3-4 minutes before shutting down. This allows the Engine and components to cool down to the proper Temperatures without overstressing different thicknesses of material.

Agree. I always let my EGT get down to normal idle temp before shutting down. Typically 3-4 minutes like you say.

[teddychamp]

The original pipe from Cummins with the rib is designed to prevent the cracking of the pipe. HOW Ever the Key to the problem is, that you must let the Engine run 3-4 minutes before shutting down. This allows the Engine and components to cool down to the proper Temperatures without overstressing different thicknesses of material.

[jauguston]

Exhaust flex pipe would not stand the pressure created by the EB. That doesn't look like a very well designed EB mount. Mounted directly to the turbo outlet is a lot better.