Rust On Stock Mufflers

[Marylandrauder]

My Dad and I have identical 04 Marauder's that are never driven in the rain and we have rust on our mufflers, like tiny little rust marks on the mufflers, I looked at hte pictures of Dennis Reinhart's picks of his exhaust and I could see some rust, aren't these stainless steel mufflers or are the mufflers restrictive in a way that moisture is trapped inside, if this is going to get worse I might have to think about the Magnaflow 18" mufflers, I do not want to be driving one day and have one or two of the mufflers fall off, any comments or thoughts would be greatly appreciated. By the way my Marauder has 22K and my Dad's has 13K.:lol:

[FordNut]

They are stainless. There are many different grades/alloys of stainless, some will rust. It will take a long, long time for them to rust through.

[Marylandrauder]

I guess then that they maybe the cheaper grade of stainless material because my Dynomax Ultra Flow SS Stainless Steel Mufflers have been on my El Camino for 5 years and look as good as the day I got them.:argue:

[Raudermaster]

Well yea, they're aftermarket and you pay for some of that and they want them to last. Car Manufacturer'es try to get away with spending a lot of money in R&D on a vehicle, but still try to make it the best they can.

[04MRADR]

I park my Marauder on an inclined driveway and sometimes there were drip marks right under the mufflers with the original mufflers. I assume these were drain holes for this purpose. So if you park on level spots I assume they don't allow moisture drainage. Your mufflers might be rusting from the inside out. I got me Magnaflows model # 14255 which are polished steel about a year or so ago and no problems so far. Originally they were not much louder than originals but with age have developed a more throaty sound which is nice. Other members have told me the media in the mufflers breaks up a bit with age and the mufflers get a bit louder. I like em louder!

[Stranger in the Black Sedan]

Your stock mufflers are going to outlast your car. Because they are part of the emissions system, they are required to be warranted past 100k miles, but they will last way, way longer than that.

Stop worrying about them, they are never going to fall off

[larryo340]

Your stock mufflers are going to outlast your car. Because they are part of the emissions system, they are required to be warranted past 100k miles, but they will last way, way longer than that.

Stop worrying about them, they are never going to fall off

While I agree that they will last a very long time, how do you figure that they are covered under emissions warranty? :confused:

[Marylandrauder]

Yes, I park the car in the garage, which is level, I will ask my Dad if we can get a new garage floor which is not level, when they redue the concrete what kind of angle should the new floor be.

[ts-pa]

They are most likely made out of 400 series stainless steel. It has more carbon in it than the 300 series. This allows easier manufacturing, is cheaper, easier to weld, discolors to a brown color with heat and will rust eventually. Most OEM ss exhaust will last about 8-10 years. The 300 series will last much longer and look nicer also.

[Drock96Marquis]

Tom is correct.

The stock mufflers (and exhaust except the tips) are T-409 stainless (at least the CV/GM/TC are, I'm sure the MM as well). Some light surface rusting from humidity or underbody washing is normal, however even in harsh winter climates it will last a LONG time.

[freakstatus]

Might I suggest the Flowmaster Super 44? Its 4" body fits snugly under and does not protrude, plus their coated black and sound awesome.

[fastblackmerc]

Yes, I park the car in the garage, which is level, I will ask my Dad if we can get a new garage floor which is not level, when they redue the concrete what kind of angle should the new floor be.

Whatever is code in your area.

[sailsmen]

Wrong, wrong, wrong! This is not what the gentleman wants to hear.

Yes, your mufflers are rusting and they must be replaced ASAP for "safety"reasons with the performance muffler of your choice!:D

You can quote me and set up the appointment for you and your dad's car immediately.

[rlbforum]

Your stock mufflers are going to outlast your car. Because they are part of the emissions system, they are required to be warranted past 100k miles, but they will last way, way longer than that.

Stop worrying about them, they are never going to fall off


From what I am told, the mufflers are a wear item. They are not covered under warranty work. I am in the process of trying to get mine done. 65k 2003 MM daily driver in Chicago winters. I even have extended warranty till 100k.

Both my mufflers are rusted around the flange on the face of the muffler, not the weld from the flange to the rest of the pipe. So basically my mufflers are hanging by the strait thru pipe that goes thru the muffler as well as the hanger tack welded to the muffler housing. Car sounds fine but get a tinging noise under light acceleration.

They are not going to fall off, but need to be replaced. If I can't find a dealer or Magnaflow to warranty them, I have no choice but to get new ones. Not the end of the world, but for stainless mufflers they are a POS. That bites cause I just put a cat back set from Magnaflow our my friends Charger. If I knew the quality was crap, I would have bought someone elses.

[thePunisher]

the federal emissions warranty is 8 yers 80k mi. the mufflers are not covered.

much of the rust spots you see are actually iron deposits which have gotten on the mufflers from normal driving etc....natural deposits coming from the road, ground etc......

also....im pretty sure the mufflers are t-304 stainless. and the tips are t-409......304 is more likely to show some rust.....

[ts-pa]

the federal emissions warranty is 8 yers 80k mi. the mufflers are not covered.

much of the rust spots you see are actually iron deposits which have gotten on the mufflers from normal driving etc....natural deposits coming from the road, ground etc......

also....im pretty sure the mufflers are t-304 stainless. and the tips are t-409......304 is more likely to show some rust.....

I think that you have the SS grades backwards, but it really does depend on who makes the parts. IIRC, Magnaflow might use 400 series for the muffler, while Borla uses 300 series.

You are correct that the rust is the iron in the SS that is oxidizing. This iron is already in the exhaust material, it does not get deposited onto the exhaust. The iron could be deposited onto the surface from manufacturing process. Such as tool steel that is used to form the sheet material into shape. That is why passivation is used to remove these deposits and remove some of the exposed iron from the surface. Now, road salt gets deposited onto the exhaust, which accellerates the rusting process. That is why it is very important to at least rinse off the underside of the car after the salt is sprayed up there.

[thePunisher]

dude youre right! i wrote it backwards.....409 is the lesser grade.... :)

[Stranger in the Black Sedan]

RLB, if I am reading your post right, you have aftermarket Magnaflow mufflers that rusted out, not stock ones that rusted out?

Interesting the mufflers are a "wear item". That sucks. I have used a lot of 150k mile junkyard stock stainless mufflers from various cars and never found a bad one -- they were not MM mufflers specifically though.

[Marylandrauder]

T-304 is the upgrade of T-409, I should know because my Dynomax Ultra Flow SS have been on my El Camino for 5 years and they look as good as the day I took them out of the box, the car is sometimes kept outside and has been driven in the rain and snow, I got on the Dynomax website and they make 1 that is part number 289-17287 that the overall lenght is 25 inches and the body or shell length is 20 inches.:banana:

[rlbforum]

RLB, if I am reading your post right, you have aftermarket Magnaflow mufflers that rusted out, not stock ones that rusted out?

Interesting the mufflers are a "wear item". That sucks. I have used a lot of 150k mile junkyard stock stainless mufflers from various cars and never found a bad one -- they were not MM mufflers specifically though.


I am pretty sure they are stock mufflers. I (we) are the 2nd owner. I bought the car from the bank when my father passed. It was his car. He picked up the car with 10k miles on it. He put about 10k on it. I have owned the car for the last 2+years so now it has 60k. So we have not touched the exhaust in 40k.

If it ever warms up in Chicago, i'll shoot a picture.

The aftermarket ones I put on were for a friends Charger. I used Borla on my 03 terminator and flowmaster on my 99 cobra. The later 2 cars are stored in winters so I don't think i'll ever need another exhaust on them.

Interesting part is that all my daily driven cars never needed mufflers until well into 120k. I try and get the undercarridge rinsed in winter to get the salt off as much as possible. Hence my dissapointment with the MM exhaust. This is why I am trying to get it covered under warranty.

[ts-pa]

There is always humidity in the air at various amounts. Any slight "dew" effect can occur even on something such as an exhaust if not used often. The daily driven cars may have less rust on the exhaust since you are always keeping them dry by the everyday heating.

[jaywish]

All I can say is my 93 GM sport still has the original exhaust & complete drive train. It has been abused badly for the last four years. The car is now a complete POS on outside and inside. But it still runs and sounds like the day I bought it in 1995.

Jay