Fixing dents in muffler

[911Etarga]

Does any one know of an easy way fix dents in your muffler? I lowered the engine out of the car the other day and the muffler met the jack....
Thanks,
Brent

[mb911]

If you seal off all the inlets and outlets then pressurize it with say 30psi then heat up the offending area the dent will pope out or just buy a new one Good luck

[scottb]

How about tack-welding a little stud to the center of the dent, and then gently heating and pulling?

[mb911]

Originally Posted by scottb

How about tack-welding a little stud to the center of the dent, and then gently heating and pulling?

not as easy to get it back to the orignal shape that way

[911Etarga]

This might sound crazy, but could you put a screw into the dent, then pull the srew until the dent pops out? Then fill the hole with ???, sand it and paint it?

[crustychief]

Detune your engine run bad gas at high rpm down a long hill!

Just kidding, be careful if you pressurize your muffler with air and then heat it. It could "pop" under some circumstances. But I would do it like mb911 said.

[Wayne 962]

Pressurizing should help. Then again, if it's a small dent, then who's ever going to see it?

-Wayne

[Zeke]

A problem with heating a concave dent is that the metal expands and the dent goes in deeper! I'm with Ben on this, it's very hard to pull a concave dent out of a convex surface. If you were to mechanically pull it out from the out side using attached studs or screws, you would work from the perimeter into the center. I doubt that pressure would help much considering the resistance the concave dent is holding. If look at any vessel intended to hold pressure and stand on it's end, the bottom will be concave. Like a gas bottle for welding.

[Tim Hancock]

I used heat and pressure on this aluminum vintage MX bike tank.... Works, but not always perfect. Steel is much easier to monitor/control heat. Pretty confdent that if it was steel, with some patience, a torch, a hammer and pressure I could have made it perfect.... As it was I had to use just a touch of bondo. At least with a muffler it does not have to be "perfect".

I used propane on the aluminum tank as I was afraid of melting the aluminum, but would use oxy/acet for a steel part.

[azasadny]

Tim,
You do great work!

[911pcars]

Dents are removed from concave and convex surfaces all the time on passenger car bodies. In some cases, the metal stretches. In most cases, its just displaced metal. Remove the stress area and you're back in business - dentless techniques included. Might be able to insert a dentless tool in back of the dent area through a strategically-placed drilled opening if you know the location of internal baffles or if it happens to be accessible through the tailpipe opening (temporarily remove tailpipe for access).

Here's an idea. Look on YouTube.com for a series of DIY videos using compressed air (CO2) to remove a dent. A muffler would be an ideal surface to experiment with especially if the wall thickness approximates that of body metal.

Some body shops use a variation of a slide hammer/spot welder. Single or multiple "nail head"s are spot-welded onto the dent area. Using a special slide hammer, each nail is pulled a bit to gradually remove the dent. Cut and grind off the nail after the dent is removed, then proceed to final metal finishing.

Sherwood

[Augustus]

Tim, That was a nice post! Thanks!!

[GBG1000]

Great work Tim!