Muffler rusts if driven short distance?

[victoreric]

I heard a rumour that if you drive a short distance regularly then your muffler may pre-maturely rusts. This is because the moisture in the muffler builds up but does not have enough time to evaporate so will just sit there and rusts off.

Is this true and if it is true, is there anything I can do to counter that. The problem is I only drive 10 minutes to work.

[rick3000]

Considering all the DD Boxsters, and DD cars in the world that have never had this problem. I don't think you should worry. I really don't think Porsche would build cars that could not be driven without rusting.

[blinkwatt]

Out of all my time spent looking at Boxster info & such I've NEVER seen a rusted part besides aftermarket brake rotors hat but thats aftermarket. You have nothing to worry about,I just wouldn't practice driving the car short periods of time all the time.

[Frodo]

I've been told that before myself, I believe by my father (who was a chemical engineer and a pretty fair mechanic). I think he was talking more about starting your car cold and driving it twenty feet into the garage, then turning it off.

In driving (even for only ten minutes), I'd venture to say the exhaust system in a Boxster (or most any car) would heat up to the point to where the small amount of water produced by combustion would quickly evaporate. Don't worry about it.

[husker boxster]

I'm not an engineer on TV and I didn't stay at a Holiday Inn (where's MNBoxster?), but I believe H2O is a byproduct of an engine that is not fully warmed up. Has something to do with meeting emissions and making the engine run smooth when its cold. So that's where the water out the exhaust comes from. If you do not reach normal operating temps before you shut your engine off, the water will not have a chance to evaporate from within the muffler, will collect there, and rust.

10 min may be on the leading edge of a fully warmed up engine. What can you do to prevent this? Take the long way to work and enjoy your Box for an extra 10 min.

Seriously, if you have not experienced a rusted muffler in your other cars in your 10 min travel to work, chances are the Box will not either. Advances in today's metals used in muffleres and coatings such as zinc make it less likey they will rust.

[rick3000]

I forgot to mention that the entire body of the Boxster is galvanized and comes with a 10 year rust free guarantee.

[mikefocke]

But that was back in the late 70s. The car was driven only a few miles at a time and sat outside.

No idea if todays muffler construction would prevent that. Took out the tailpipe too.

The 987 Boxster has a stainless steel exhaust system, so I don't think rust is an issue. I would bet the 986 has a SS exhaust too.

[blinkwatt]

Originally Posted by rick3000

I forgot to mention that the entire body of the Boxster is galvanized and comes with a 10 year rust free guarantee.

What is galvanizing?

[OldBlevins]

If you want to be absolutely sure, drive it for that 10-minute trip to work, then touch the muffler with your hand.

I'd also recommend getting some ice on that burn right away.

Originally Posted by blinkwatt

What is galvanizing?

http://www.galvanizeit.org/showContent,42,74.cfm

[OldBlevins]

Good link, bmussatti.

Blinkwatt, a good example of this is nails. Galvanized nails have a rougher, duller finish, but don't rust the way straight steel nails do. You may have seen them.

I think this is a picture of a Porsche being galvanized:

[blue2000s]

Water is a byproduct of combustion, in a VERY simplified form,

2HC + 5/2O2 -> H2O + 2CO2

When the exhaust isn't warmed up, the H2O from combustion can become cool enough to condense on the inside walls of the exhaust tubes and muffler. The further down the exhaust you go, the more likely the exhaust will be cooler, and the more likely it is to find water. Ever wonder why mufflers rust out before anything else? This is one of the reasons (not the only one, of course).

In order for the water to completely re-vaporize, the entire exhaust system has to reach at least 212F. This amount of time varies with the engine, the exhaust system, the way it's driven, the conditions outside and a few other things.

There's really no set amount of time that you can say for sure that the muffler's up to temp, but 10 minutes might be on the short side, especially on cold days. You could measure the muffler in an unshielded location to tell if it's reached this point.

Zinc plating (galvanizing) works great initially to protect steel if the surface is well protected and metal forming is done either before plating or is fairly minor. A lot of times, holes are drilled or bends are made after the plating process, exposing the steel to the environment.

But zinc plating wears out eventually, the speed of which is dependent on the environment to which it's exposed. But the more often the exhaust is exposed to moisture, the shorter the amount of time it will be protected by the plating.

You guys are kinda missing the point. He wants to know if short distances (not getting up to temp) repeatedly will accumulate enough water to rust a 986 muffler. Main factors: amount of water, type of metal, temperature.
Most of this has been addressed in some way. Fire creates water, water condenses on cool metal, metal rusts. I would say that the muffler is stainless steel, it gets wet all the time and doesnt rust. Look at the bolts that attach it to the car, those rust like a mother, yet the muffler does not. It may not be polished, but the type of material is stainless. All this talk of zinc plated does not prevent rust, the zinc is a sacrificial metal to keep the integrity of the steel intact.

Main point, always let a car get to running temps and everything will be better.