Exhaust dent removal

[John Minchell]

Anyone got a clever way to remove dents from tuned pipes when you can't get to the inside with a tool?

And the pipes are the expensive Krumscheid tuned expansion chambers so I don't want to start cutting them open as my aluminium welding is well out of practice?

TIA John M

[Engine Doctor]

The pipe part should be easy if you can get a rod along to the  dent. The canister is a bit of a problem though . The dent shouldn't affect its performance though just looks ugly . My only suggestion would be to drill a hole to pull or push the dent out then fill the hole with low temp Ali brazing rod the grind down the filling and polish . You can anneal the earea first by heating with a smear of soap on the area and when it turns black plunge it into cold water. This will soften the ally and make it easier to reshape. 

[Don Fry]

Crude fix, Engine Doctor reckons it will still work. Leave alone, fill the dent.

 

But I feel the pain, been there. Game of blood. 

[john stones 1 - Moderator]

I would leave it alone, the header part looks like it'll fracture if you set about it.

[GrumpyGnome]

Just leave it. Won't make much difference.... ignore the aesthetics

[John Minchell]

Thanks for the replies chaps.

John M

[Jon H]

Fill it with water and freeze it? it might completely explode though

[Mike T]

You may be able to raise that 'crease' a little by annealing then tapping gently (many, many taps) on either side with a planishing hammer.  You wont get it out completely without a mandrel of some sort.  How big is the aperture at the engine end?

[John Minchell]

Mike, the crease is 165 mm along the taper from the open (inlet) end and dia from the exhaust header is 21mm.

The dent at the exit end of the pipe is 46mm in from the rear end and its only 14mm dia.

So can't get a curved mandrel in big enough or strong enough to do the job.

[Mike T]

OK - assuming the pipe is straight and with no baffles up to the point of the crease, then you only need a mandrel with a reach of, say, 180mm.  A 300mm length of 15mm dia steel rod with the end rounded to a hemisphere and mounted in a bench vice should give you enough overhang to get at the crease.  I'd try working the pipe over the mandrel by hand to start with and if it proves too stiff, then resort to the hammer.

 

If the pipe is baffled, then you've got no means of working the outlet dent, other than major surgery.  Rotate the pipe so it's facing the airframe 😉

Edited February 22, 2023 by Mike T
missing dims.

[John Minchell]

Ah never thought of gripping the bar in a vice and working the pipe in my hands.  Will try it at the weekend.  Thanks Mike.

[Bruce Collinson]

If I had to do that, I’d try to get the local Dentmaster bloke to look at it as I understand they carry mandrels of all shapes and sizes.

BTC