Mufflers (silencers in the UK) generally rust from the inside out,
especially if the car is used for many short journeys. Water vapour in the
exhaust condenses on cool surfaces (like the inside of the silencer) and if
that surface does not get hot enough to burn off the water, the rusting
process begins. Painting the outside will not prevent this.
Having said that, I believe that 'custom car' type shops sell exhaust
manifold (headers for our friends across the pond) paint. If it will cope
with the temperatures there, the silencer should not present a problem.
The middle muffler is double walled so the outer wall rust is not important.
The rear muffler is common to rust by the tailpipe... you can try the rust
converter to neutralize that rust... but you probably can't extend the
muffler's life by that much...
I typically get 7+ year on rear muffler... and more on center muffler... so
with that much life, it is not worth the effort to try to save it.
thanks a lot for the tips. I mainly drive HWY 70miles a day. Given that,
according to your reasoning, it will unlikely to rust from inside. The
system is still solid, but the welding circumference is getting bad, esp.
because I forgot the wash the underbody after last snow season.
Rust converter has been pretty effective in my other body project, but not
sure it will work on the high-temp exhaust system. Will try.
I bought high-temp paint, but it all requires a baking at 500F for 2 hours,
which is impossible for me. normal driving even hour-long idling wont
deliver such high temp for needed cure.
again, many thanks for sharing your knowledge.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.