MPE cracked..... Again!!!

[Alvinized52]

Damn! My MPE was rattling at start up so i took a peek earlier and noticed it cracked again. I thought repaired it a year ago... but new cracks appeared. Not sure if this is repairable again. Those of you that repaired your MPE... did yours crack again?

Aside from re-welding again, anyone else have any suggestions on reinforcements?

***And yes, i know of 2yr BMW warranty replacement... but i bought mine used over 2years ago and not dealer installed so BMW doesn't cover mine unfortunately.

[M4_CaptFlashheart]

Find a good welder who will re-weld it and add a couple of stiffeners to it. There must be quite a lot of unsupported load on the weld join. Not saying this is the only solution but it definitely needs more strengthening in that area. May need 2-4 strengthening pieces.

[Arcades]

I remember your taking it to my SA. Maybe he has an idea.

Worth asking but definitely re weld.

[08mojo]

Make sure the cracks are drill-stopped before they are re-welded. I would also add a reinforcement plate:



As M4 UAV said, I'd also add some stiffeners, but not without the reinforcement plate. The wall of the muffler is too thin, so I think the cracks would come back just adding the stiffeners alone.

[FirstF80InSpace]

Good info in this thread.

[Wmf80]

Always wanted this exhaust but this is the very reason why I haven’t. How does BMW not find a solution to this issue, or repair if cracked since they won’t replace it. Very curious to see of a solid fix and maybe I’d purchase one.

[Alvinized52]

Originally Posted by Arcades

I remember your taking it to my SA. Maybe he has an idea.

Worth asking but definitely re weld.

Mine isnt under warranty cuz i bought it used.

[Alvinized52]

Originally Posted by 08mojo

Make sure the cracks are drill-stopped before they are re-welded. I would also add a reinforcement plate:



As M4 UAV said, I'd also add some stiffeners, but not without the reinforcement plate. The wall of the muffler is too thin, so I think the cracks would come back just adding the stiffeners alone.

Originally Posted by M4 UAV

Find a good welder who will re-weld it and add a couple of stiffeners to it. There must be quite a lot of unsupported load on the weld join. Not saying this is the only solution but it definitely needs more strengthening in that area. May need 2-4 strengthening pieces.

Originally Posted by 08mojo

Make sure the cracks are drill-stopped before they are re-welded. I would also add a reinforcement plate:

[img]https://farm2.staticflickr.com/1806/...f904ee09_o.png[/img]

As M4 UAV said, I'd also add some stiffeners, but not without the reinforcement plate. The wall of the muffler is too thin, so I think the cracks would come back just adding the stiffeners alone.

Thanks for the input, Gents! I found these pics online while searching for solutions. What do you guys think of these support bars on top and bottom of both sides??

[08mojo]

That would help, as it transfers the load to the seam of the muffler and off of the wall of the muffler. Regardless of which repair you choose, it is very important to drill-stop the existing cracks--otherwise they will come right back.

[420Coupe]

Originally Posted by wreckedmyf80

Always wanted this exhaust but this is the very reason why I haven’t. How does BMW not find a solution to this issue, or repair if cracked since they won’t replace it. Very curious to see of a solid fix and maybe I’d purchase one.

They did create a solution. This is their old version; havent heard of any cracks on the new version.

[Yachtmaster]

Originally Posted by Alvinized52

Damn! My MPE was rattling at start up so i took a peek earlier and noticed it cracked again. I thought repaired it a year ago... but new cracks appeared. Not sure if this is repairable again. Those of you that repaired your MPE... did yours crack again?

Aside from re-welding again, anyone else have any suggestions on reinforcements?

***And yes, i know of 2yr BMW warranty replacement... but i bought mine used over 2years ago and not dealer installed so BMW doesn't cover mine unfortunately.

I would highly suggest you look into the chart below:


the repair welds on the exhaust appear to be grey/white indicating contamination/impurities with the repair weld thus indicating compromised strength. titanium needs to be welded in a purged environment to ensure strength, it appears as though whoever repaired this did not purge, thus prone to cracking again/damaging the metal. i am certain that the repairs welds cracked due to the above.

the actual process of welding titanium isn't all that different from welding stainless steel, but a purged environment is 100% crucial when it comes to titanium. i would find a shop that specializes/works with titanium often or it wont matter what kind of reinforcement plates are added if the correct procedures aren't taken in place to handle the metal.

[08mojo]

Originally Posted by kpsupreme

I would highly suggest you look into the chart below:


the repair welds on the exhaust appear to be grey/white indicating contamination/impurities with the repair weld thus indicating compromised strength. titanium needs to be welded in a purged environment to ensure strength, it appears as though whoever repaired this did not purge, thus prone to cracking again/damaging the metal. i am certain that the repairs welds cracked due to the above.

the actual process of welding titanium isn't all that different from welding stainless steel, but a purged environment is 100% crucial when it comes to titanium. i would find a shop that specializes/works with titanium often or it wont matter what kind of reinforcement plates are added if the correct procedures aren't taken in place to handle the metal.

^this...wasn't even thinking about the exhaust being titanium.

[Alvinized52]

Originally Posted by kpsupreme

I would highly suggest you look into the chart below:


the repair welds on the exhaust appear to be grey/white indicating contamination/impurities with the repair weld thus indicating compromised strength. titanium needs to be welded in a purged environment to ensure strength, it appears as though whoever repaired this did not purge, thus prone to cracking again/damaging the metal. i am certain that the repairs welds cracked due to the above.

the actual process of welding titanium isn't all that different from welding stainless steel, but a purged environment is 100% crucial when it comes to titanium. i would find a shop that specializes/works with titanium often or it wont matter what kind of reinforcement plates are added if the correct procedures aren't taken in place to handle the metal.

Thanks! But what exactly does "purge" mean? Given that it may be difficult to clean contaminants inside the can... Does this mean, im pretty much fucked at this point?

[Yachtmaster]

Originally Posted by Alvinized52

Thanks! But what exactly does "purge" mean? Given that it may be difficult to clean contaminants inside the can... Does this mean, im pretty much fucked at this point?

i'm not sure what kind of fixes they can do or perhaps reweld a plate over, that whole gray/white piece of metal looks contaminated. i'm definitely no metal expert - just know there are certain grades of weld/metal color acceptability when it comes to metals, and especially for titanium it is especially reactive to oxygen when heated. this weakens the strength/structure of the metal, causing titanium to be more brittle/prone to breaking/cracking if contaminated. argon purging is done to remove oxygen/nitrogen out of the environment while the metal cools as to avoid contamination. i believe there are purging chambers and/or methods to pump argon during the repair process, just something to check as a necessary step when finding your repair shop, as this step is 100% crucial. i'd def check back with your shop who did the repair to ask if they purged the metal

edit, the exhaust may not fit in a chamber but just a cool example of a purging:

[rubber_ducky]

Originally Posted by 420Coupe

They did create a solution. This is their old version; havent heard of any cracks on the new version.

To my knowledge, the “new version” that you speak of isn’t released yet. Which may explain why there haven’t been reports of cracks yet. Do you know otherwise? Can you give us a part number for the new version?

[BzsBimmer]

Originally Posted by rubber_ducky

To my knowledge, the “new version” that you speak of isn’t released yet. Which may explain why there haven’t been reports of cracks yet. Do you know otherwise? Can you give us a part number for the new version?

That was also my question as well. I’ve heard there is a new version out but the pn doesn’t appear to have changed on realoem. There could always have been a revision change with the same pn but then how do the dealers know?

[Alvinized52]

Just got it back from being repaired. Also added support brackets. I will report back after its installed if sound is affected. Hopefully start up rattle is cured.

[Caliboy951]

The more you heat cycle grade 2 Ti the more it becomes brittle. Once you weld it, it will be prone to crack even faster.
I build exhaust systems for a living (mostly off-road) and Ti systems are for the race teams that swap out systems often.
Ever wonder why just the smallest pebble will crack a Ti header...you guessed it, because it was heat cycled many times.

[Alvinized52]

Originally Posted by Caliboy951

The more you heat cycle grade 2 Ti the more it becomes brittle. Once you weld it, it will be prone to crack even faster.
I build exhaust systems for a living (mostly off-road) and Ti systems are for the race teams that swap out systems often.
Ever wonder why just the smallest pebble will crack a Ti header...you guessed it, because it was heat cycled many times.

Well... i hardly drive my car. So If it cracks again then I will swap out. For now, i will take my chances with $125 repair job over spending $4k+ for a new exhaust system. Hope the brackets help support sidewalls and keep from flexing.