How to clean and restore exhaust system

[wilnj]

I知 looking at going back to OE on my E46 exhaust system. I found the system below but wanted to clean it up and protect it before install. Not looking for a polished finish. Rather something I値l get another 150k miles out of.

Any ideas?


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[Ayles]

I used barkeepers friend when I cleaned up the muffler on my 911. Still looks great after several years.

[908/930]

Tan coloured scotch-brite pad works well for stainless. Can cut into 5" round discs and mount on to a small right angle grinder, but need a way to slow down the grinder to about 3000rpm.

[Zeke]

If you can fine a dry ice blaster that would be great. Probably not cheap and maybe more than what you need.

You can get a lot done with SOS or Brillo pads. I usually start there. Sometimes it takes a little phosphoric acid and a fine Scotchbrite pad. To knock through any grease and grime before getting on to the finer brightening, use any of the powerful cleaners like Zep, Purple Power, Simple Green — just use what you have on hand. IDT one is that much better than another.

However, one thing that I have found to be really effective cleaning my hands is Dawn Powerwash and Boraxo hand powder combined. I have also used GoJo Orange hand cleaner lightly on wood finishes that are old and grimy.

[wilnj]

Thanks, I don't believe the OE system is stainless and I'm not looking to polish it. I want to clean it up, mainly to ensure there are no pinholes hiding under the rust.

I have a right angle grinder, would a wire wheel with little to no pressure be too aggressive?

[herr_oberst]

Originally Posted by wilnj

Thanks, I don't believe the OE system is stainless

You may be surprised. It looks like there's a lot of stainless there to me, but the picture might be deceiving.

[wilnj]

Originally Posted by herr_oberst

You may be surprised. It looks like there's a lot of stainless there to me, but the picture might be deceiving.

Yes, I haven稚 put eyes on it and the system on my car is a Magnaflow cat back so I don稚 have anything to compare it to.

But the fact that it looks as clean as it does behind the front muffler is encouraging.


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[Zeke]

You can buy real brass wire wheels. It's a specialty item but other than what the wheel picks up, it shouldn't scratch or polish the SS. Most angle grinders (corded anyway) are brushed motors and can be slowed with a dimmer of enough wattage. Or you can buy a controller. There are brass plated wheels so don't assume.

For slowing down I just use a drill motor instead. I have one that is actually 3000 RPM and that is a good speed for control. The Scotchbrite at grinder speed will disintegrate. SB's are not terribly durable and hand use is recommended unless you buy a SB wheel intended for machine operation.

The exhaust may not be a high grade of SS but I bet that's the majority of the metallurgy.

[john70t]

Originally Posted by wilnj

I want to clean it up, mainly to ensure there are no pinholes hiding under the rust.

Stick a rag in the end. If it keeps running..

[Otter74]

Originally Posted by john70t

Stick a rag in the end. If it keeps running..

Everyone knows you need a potato to do the test right.

[908/930]

I would think that is stainless steel exhaust. Whatever you do do not use a steel wire wheel on stainless. Never liked wire wheels for clean up, those wires shoot everywhere.

[Seahawk]

I know a guy at Auto Zone who is an expert

Interesting thread: Hope it works out!

[wilnj]

Originally Posted by Zeke

You can buy real brass wire wheels. It's a specialty item but other than what the wheel picks up, it shouldn't scratch or polish the SS. Most angle grinders (corded anyway) are brushed motors and can be slowed with a dimmer of enough wattage. Or you can buy a controller. There are brass plated wheels so don't assume.

For slowing down I just use a drill motor instead. I have one that is actually 3000 RPM and that is a good speed for control. The Scotchbrite at grinder speed will disintegrate. SB's are not terribly durable and hand use is recommended unless you buy a SB wheel intended for machine operation.

The exhaust may not be a high grade of SS but I bet that's the majority of the metallurgy.

Originally Posted by 908/930

I would think that is stainless steel exhaust. Whatever you do do not use a steel wire wheel on stainless.

Thanks. I知 glad I asked. If it is in fact stainless (I guess I should check an E46 forum to confirm) I am less concerned with corrosion and may just do some handwork to clean it up but nothing aggressive.


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[red 928]

carbon steel exhausts rarely last
beyond 50 or 60k miles,
that's why they stopped putting them
on new cars a long time ago.
The smog warranty requirements from the DOT
preclude it's use.

What you are discussing is cosmetic and
I fail to see value in the effort.

[wilnj]

Originally Posted by red 928

carbon steel exhausts rarely last
beyond 50 or 60k miles,
that's why they stopped putting them
on new cars a long time ago.
The smog warranty requirements from the DOT
preclude it's use.

What you are discussing is cosmetic and
I fail to see value in the effort.

Thanks. I guess I知 going off my experience with a 2011 Jeep with an exhaust that rusted through in 2 spots. Granted it was more than 10 years old at the time and seen a fair bit of seawater.


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[wilnj]

UPDATE: Seems like the OE exhaust is 409 SS which will develop surface rust, particularly where it's been exposed to heat. That makes sense, since the exhaust in my photo looks like it gets worse as you get closest to the heat source.