Flowmaster corroding after only 17 mo.

[navyflyer]

Greetings,
I installed a FM Force II black cat back exhaust on my JL in Sep21, noticed this the other day. Problem I have is that my Jeep has only 4500 miles on it (roughly 3000 miles with that exhaust) and has been garage kept. I called FM and never got off hold. Thought I’d post this and see what y’all think or if y’all have had any experience like this. Thanks.

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[JJ_WA]

I was going to say if there are no actual rust holes, perhaps a wire brush and some black Rustoleum make it look better. But, it looks like you have rusted through in some spots.

I'd keep trying to contact the seller/manufacturer. Sorry.

 

[Headbarcode]

Greetings,
I installed a FM Force II black cat back exhaust on my JL in Sep21, noticed this the other day. Problem I have is that my Jeep has only 4500 miles on it (roughly 3000 miles with that exhaust) and has been garage kept. I called FM and never got off hold. Thought I’d post this and see what y’all think or if y’all have had any experience like this. Thanks.

Looks like that whole system was constructed from T-409 stainless, and that grade is prone to surface rusting in wet environments. Salty conditions will accelerate that. This grade is better used in drier climates.

I live in a wet and salty environment, so I made sure to go with a system that's made out of T-304 stainless. This grade fully prevents rust from forming, but it will discolor over time due to heat.

 

[navyflyer]

Looks like that whole system was constructed from T-304 stainless, and that grade is prone to surface rusting in wet environments. Salty conditions will accelerate that. This grade is better used in drier climates.

I live in a wet and salty environment, so I made sure to go with a system that's made out of T-406 stainless. This grade fully prevents rust from forming, but it will discolor over time due to heat.

Which exhaust did you get?

 

[navyflyer]

Just hung up with Holley, they’re sending me a new one. No problem, pretty impressed actually.
Question is, what do I do with it? It’s probably gonna rust again. Any coatings I can add?

She said these have a great warranty…guess I’ll keep on sending it back…I really like the look dual tip look and the sound is exactly what I was looking for.

 

[Headbarcode]

Which exhaust did you get?

The Borla Touring Climber cat-back. I was wanting to maximize departure angle and ground clearance, and this particular system doesn't have a transverse mounted muffler behind the rear axle.

Borla also has dual exit systems in both black ceramic coat and raw stainless with polished tips. They are also available in 3 sound levels: Touring being the quietest but still a nice rumble over stock, S-Type is the mid sound level, and Atak being the loudest. All Borla systems are constructed from T-304 stainless steel.

For future reference, any companies that use T-304 will always mention it in their product descriptions because it is the higher quality option out of these 2 most commonly used grades of stainless. If a specific grade is not listed, or they use wording such as high quality stainless, it is most definitely T-409.

 

[Headbarcode]

Just hung up with Holley, they’re sending me a new one. No problem, pretty impressed actually.
Question is, what do I do with it? It’s probably gonna rust again. Any coatings I can add?

She said these have a great warranty…guess I’ll keep on sending it back…I really like the look dual tip look and the sound is exactly what I was looking for.

Great to hear that they are taking care of you. Unfortunately, unless they've drastically changed their coating, it's most likely going to rust again. Only thing that comes to mind, is if you're willing to seak out a reputable company that can seal it with a high quality finish.

The claim made by many exhaust manufacturers is that T-409 will rust, but that it's only a surface coating that won't rot through. And that it should last about 7-8 years, whereas T-304 will last 10 years in the same climate.

I make no claims of being an exhaust guru or a metallurgist. Just sharing what I've learned.

 

[Opus]

Maybe hit it with this:

https://www.amazon.com/Rust-Oleum-7778830-Enamel-Spray-Bar-B-Que/dp/B0010O0C94

before you install it? It might buy you a little time before corrosion catches up with it again.

 

[navyflyer]

The Borla Touring Climber cat-back. I was wanting to maximize departure angle and ground clearance, and this particular system doesn't have a transverse mounted muffler behind the rear axle.

Borla also has dual exit systems in both black ceramic coat and raw stainless with polished tips. They are also available in 3 sound levels: Touring being the quietest but still a nice rumble over stock, S-Type is the mid sound level, and Atak being the loudest. All Borla systems are constructed from T-406 stainless steel.

For future reference, any companies that use T-406 will always mention it in their product descriptions because it is the higher quality option out of these 2 most commonly used grades of stainless. If a specific grade is not listed, or they use wording such as high quality stainless, it is most definitely T-304.

Quadratec discription says Borla S-type as being made of T-304….and Flowmaster Force II is T-409.

“409 stainless steel can contain up to 90% iron, meaning a magnet will stick to it and is prone to rust. 304 stainless steel is the highest quality material used for exhaust partsand has a much lower quantity of iron. A magnet will not stick to it.”

So , there you go, more iron in 409….

I think I’m gonna hit the new one with that paint, and go with it. Maybe mine was defective, no reason to rust so quickly with that little mileage. If it rusts again, call Holley and get another one. Maybe sell that one new and go Borla.

 

[Headbarcode]

Quadratec discription says Borla S-type as being made of T-304….and Flowmaster Force II is T-409.

“409 stainless steel can contain up to 90% iron, meaning a magnet will stick to it and is prone to rust. 304 stainless steel is the highest quality material used for exhaust partsand has a much lower quantity of iron. A magnet will not stick to it.”

Apologies! I had them backwards and wrongly swapped the 9 for a 6.

I'll head back and correct my previous posts, so as to not further confuse the conversation. Thanks for catching my mix up!

 

[navyflyer]

No e

Apologies! I had them backwards and wrongly swapped the 9 for a 6.

I'll head back and correct my previous posts, so as to not further confuse the conversation. Thanks for catching my mix up!

No worries , thanks for the help. I ordered a can of VHT FLAMEPROOF flat black, $23. Got good reviews. We’ll see how it goes…

 

[blnewt]

No e

No worries , thanks for the help. I ordered a can of VHT FLAMEPROOF flat black, $23. Got good reviews. We’ll see how it goes…

I've used that VHT Flameproof on my old Infiniti exhaust cans and it worked great, should be a good plan to pre-coat w/ that prior to install.
FWIW my Magnaflow black dual axleback has been flawless w/ the paint coat, wonder what the difference is between that and the Flowmaster coating and steel used???

 

[navyflyer]

I've used that VHT Flameproof on my old Infiniti exhaust cans and it worked great, should be a good plan to pre-coat w/ that prior to install.
FWIW my Magnaflow black dual axleback has been flawless w/ the paint coat, wonder what the difference is between that and the Flowmaster coating and steel used???

Thanks for that. IDK, I think it had a defect. NEVER seen one rust out like that so fast, with under 3000 miles through it. Anyway. I’m gonna put a few coats on and see. Happy Flowmaster ponied up on this.

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