# Exhaust System Corrosion the cause of my MIL being on



## Vetterin (Mar 27, 2011)

Except for the exhaust flange your underside looks really good. Did your bolts actually break? FWIW, mine still looks okay after 86,000 miles.


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## Jim Frye (Mar 16, 2011)

Flanges & welds always rust first. Only the tubing is SS in most systems. The one on my 13 yr. P5 looks like yours. Broken bolts are another thing..


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## Robby (Mar 1, 2013)

Awfully young car for the studs to rot/break......some serious chemical action taking place.

A good muffler shop will drive out the remains and reassemble with stainless fasteners and a new gasket......you'll have a better system than you started with.

Rob


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## diesel (Jun 8, 2013)

Wow! I've never seen anything like that on such a new car. I should take a closer look at mine since it always gets ridden hard and put away wet.


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## obermd (Mar 3, 2012)

Is that not covered under the corrosion & rust through warranty? I've never seen something like this happen, even on 10+ year old cars. Rusted out pipes yes, but not bolt shearing.


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## chevrasaki (May 1, 2015)

Looks like the exhaust on my 2014 1.4L turbo 6-speed manual 1LT doesn't even have a flange.


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## Robby (Mar 1, 2013)

The 1.4 flange is up near the turbo.

The rust warranty is specific to body sheet metal.

Rob


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## bostonboy (Apr 8, 2015)

when I painted my rotors & calipers & bracket (eastwood 2 part paint) I had extra paint & my car was all apart w/ 128 miles lifts 2' off the ground so I painted all the welds & flanges. I know i'm doing a big brake kit as I type this & ordered the same paint again & will have even more left over so I will be looking to do a redo on some of my exhaust. I know my rotors & brake calipers look almost like when I painted it. I also rotate my own tires & clean & wax my rims every 5,500 miles. they looks like new too. I can't believe @ 16,300 miles my tires still have the rubber knobbies on the sidewalls all around. I also rhino lined the whole bottom what a PITA that was taping everything you don't want coated. then having to untape it with in hrs or you have to razor the tape off. then all the clear bra on her too about 40% of her all to see if this extra stuff will make my car look better in 10 more yrs than w/o it.


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## ChevyGuy (Dec 13, 2014)

Something smells. I can't imagine the bolt shearing off without mechanical stress. What's the story on the other bolt? I'm wondering if the one we see was sheared at the factory and it's been on one bolt all this time. I sure don't see any fresh damage on it - like a clean face like I'd expect to see.


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## MP81 (Jul 20, 2015)

ChevyGuy said:


> Something smells. I can't imagine the bolt shearing off without mechanical stress. What's the story on the other bolt? I'm wondering if the one we see was sheared at the factory and it's been on one bolt all this time. I sure don't see any fresh damage on it - like a clean face like I'd expect to see.


I agree - the exhaust bolts on my '98 Cavalier, holding the cat into the exhaust system, had all but disintegrated (they looked like little pins) - and everything still held together.

I thought the exhaust was all stainless...hmm...


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## Diesel Dan (May 18, 2013)

The exhaust is a very poor grade of stainless, imo. We have 30k on ours and I'm not impressed. The tailpipe on my 2000 k3500 TD looked better when I took it off a few weeks ago for a 4" system.


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## spaycace (Feb 9, 2012)

There's one post here with a welded system ... and to my knowledge/past experience, I don't recall there being flanges near the muffler on two vehicles that I've replaced the exhaust on with aftermarket. Are you the original owner? Is it a 1.4 or 1.8? If you're not the original owner, I wonder if some exhaust work was done for whatever reason ... but then again, with parts of the cars being made outside the U.S. I can imaging the quality control isn't the greatest, nor is the material being used. Best of luck with that one! If you have a good dealership and you're the original owner, they should help you out. (He!! ... even if you're NOT the original owner, they should help you out)


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## Robby (Mar 1, 2013)

spaycace said:


> There's one post here with a welded system ... and to my knowledge/past experience, I don't recall there being flanges near the muffler on two vehicles that I've replaced the exhaust on with aftermarket. Are you the original owner? Is it a 1.4 or 1.8? If you're not the original owner, I wonder if some exhaust work was done for whatever reason ... but then again, with parts of the cars being made outside the U.S. I can imaging the quality control isn't the greatest, nor is the material being used. Best of luck with that one! If you have a good dealership and you're the original owner, they should help you out. (He!! ... even if you're NOT the original owner, they should help you out)


The OP is a diesel......that is the flange at the catalyst they use......the diesel has no muffler.

I suspect this may happen more often down the road......diesel exaust, with exception to regen, runs rather cold and this failure may be due to the area never really drying out.

For now, I'd recommend the diesel crowd, especially those operating in the salt belt, take a peek down there.

Rob


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## Gator (Jul 14, 2013)

Bumping up this post to see if any others are having a issue on this. Two on here have a true separation of the pipe. Mine is pretty nasty and soon could happen also..


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## MP81 (Jul 20, 2015)

I need to hop under and have a look at mine. If need be, I'll just spray it with...well, something...to help keep it clean. Stainless fasteners would help on the bolt front.


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## Gator (Jul 14, 2013)

Wish it was that easy,just change the bolts but there spot welded studs


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## MP81 (Jul 20, 2015)

****, well that is a problem. 

This should be covered under corrosion and/or powertrain - at least until that warranty is up. Then it looks like its time for new flanges and bolts. Gross. Why the **** isn't this stainless?


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## Tomko (Jun 1, 2013)

As I've posted in the similar thread: http://www.cruzetalk.com/forum/64-g...ion/164890-detached-exhaust-scr-catalyst.html



Tomko said:


> ...my dealer told me about a year ago that my exhaust separated somewhere under the car and caused a code to set. The dealer had no idea what had caused the separation - but suspected that it was ice damage. They replaced the bolt at no charge and I haven't thought about it since.


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## Robby (Mar 1, 2013)

The studs and flanges are not stainless.....the pipes are a low grade stainless called T-409.......The higher the number (409) the lower the chrome content and it will be more ferrus (slightly magnetic)........that is why the pipes develop little rust pimples.
The flanges will fail but likely when quite old.....there is a lot of material there to corrode away.

Regarding the studs.......a exaust shop will simply red hot the flange surrounding the stud head......this makes the spot weld so soft it releases as the stud is driven out of the flange......done correctly, the stud will be red hot, the flange will not.

As I said earlier, drive out the studs and replace W/stainless nuts/bolts/lockwashers......these are always T-304.
GM specifies a grade 8 stud and nut......this hardness only can be achieved with ferrus steel.

Stainless steel fasteners are, at best, a grade 5, so they must be tightened to a lower value than the factory recommended.......that's OK though since you are only crushing a asbestos type gasket.......it works just fine and will outlast the system.

Rob


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## Gator (Jul 14, 2013)

Thx Rob on the grade of bolt to use


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## Cruz15 (Mar 17, 2016)

I would buy 316L ss bolts better corrosion resistance and heat tolerance.
Fastenal says 309, 310, 314 and 330 ss is best for Corrosion and high heat combo.


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## putercents (Apr 1, 2016)

Just out of school I worked for a company that manufactured commercial stainless steel cooking appliances. We manufactured the 5 gallon stainless pots that KFC used to heat their gravy (not sure if that was a Canada specific product) After 6 months to a year all the pots started to develop corrosion. The gravy was actually eating the 304L grade stainless. An expensive upgrade to 316LL stainless was required for this application. The heat and acidic content actually corroded what normally was an excellent material for most food items.


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