I Hit My Car with a Hammer, or The Muffler Change

You don't have to be an expert to diagnose this muffler problem.

 As it turns out, that muscular "growl" of the engine was a series of small rusted holes in the muffler. Over the weeks, the growl got steadily louder until the other day when it became nearly deafening.  A quick peek under the car revealed a softball sized hole in the muffler where the small holes joined to let loose a big section of rusted metal.  I'm suspicious that the muffler had silver paint over a rusty section when I bought it, but no big deal I had already noticed the visible rust on it and had planned on replacing it. Turns out this is one part that has gotten scarce, but I was able to track one down from a supplier in Michigan: $89.95 plus shipping from the "Little British Car Company" (www.lbcarco.com).

Shiny new muffler fresh from the box.

All the previous muffler work I've had done on my cars involved welding, which I am not up to yet.  However on the MGA and many old cars, the muffler is "just" clamped on with a single clamp.  So I loosened the bolts, and in a foolish display of the kind of optimism that only comes from a complete lack of knowledge and experience pulled on the end of the muffler.  No movement. The clamp by design snugs the muffler input pipe around the exhaust pipe coming from the engine.  Advice from the MG Forum says to "Twist / Yank / Pull / Hammer / Cuss..." and repeat as necessary. Emboldened, I head out with the one pound copper headed hammer used to loosen the wheels (more on that later). After a lot of serious bangs I had succeeded in denting the muffler, but it had not budged.  Back to the forum for more advice - apparently slicing the outer pipe may be necessary to allow the joint to open up. Navigating a hack saw in is tricky as there are things you don't want to accidentally cut, most importantly the brake line and emergency brake cable.  Also, laying on your side it is difficult to accurately cut only through the outer pipe (muffler input) without slicing the inner pipe (exhaust from engine). I do the best I can hacksawing and prying metal apart with a screw driver (don't do this at home) and come up with what I think is a pretty good opening in the outer pipe, pictured below.

The result of about a half hour of hacksawing and prying metal.

The joke is on me.  After repeating similar procedures as best as possible on the top of the pipe I determine I'm going to need to get more drastic.  I don't have a big angle grinder, but for a few dollars I'm able to pick up some metal "cut off" wheels for my Dremel. Sparks fly (remember, this is right next to the gas tank)  as I slice as long a groove as I can into the top, bottom, left and right of the pipe without cutting into the face of the muffler.  After more screwdriver abuse I'm starting to get the "banana peel" look I was going for.  More banging with the heavy hammer produces a rusty cloud of dust and a seriously deformed muffler, but not one tiny budge.  Going farther, I slice into face of the muffler and through the thick weld holding the pipe to the end of the muffler on top and bottom and pound away again.  This has to do the trick. Nothing.

Slicing with the dremel.  Notice the seriously dented muffler now.

I consider cutting all around the face of the muffler to free the pipe, but it's going to be too hard to navigate the Dremel.  I consider removing the entire exhaust pipe up from the engine back - probably 6 more bolts (if I can reach the exhaust manifold without removing the carburetors and everything else in the way). In the end, I decide to try an elegant solution I'd had in mind from the beginning.  I filled up a one gallon Ziplock back with ice and water and drape it over the "upstream" part of the pipe, and go inside to watch TV for a half hour.  I came back out and banged with the big heavy hammer three times.  Off flew the muffler to the ground.  I just stared at my vanquished foe, half in disbelief.  Wish I'd tried that about two hours earlier.

The lifeless carcass of my enemy showing the banana peel effect on the pipe. I think you can see the marks from the hammer.

Here you can see where I sliced through the weld, which was easier as the muffler became more distorted.

From here it was anticlimactic.  The new muffler slid on easily and clamped in place.  Probably another 15 minutes including reattaching the bracket at the back.  I took it out for a test drive and was shocked at how much quieter it was.  Since the car had slowly gotten louder over the last month (and probably started with some holes) I hadn't realized how loud it had gotten until the new muffler was in place.  Below are some additional photos and details for any who need to do this themselves. I think I've decided that next time I'm going to buy the stainless steel system and replace from the engine on back to avoid the need to do this again.  It's expensive (about $400) but it's guaranteed for life against rust.

The innocent looking clamp, just removed. Those were happy, optimistic times.

The little package of British cookies included with the muffler from Lbcarco.

Grinding the back side of the pipe trying to keep the sparks out of my face. Here you can see the old muffler was installed in the "wrong" position, tail pipe pointing down.

Taking the wheel off for better access is a must.

The label on the new muffler, showing the original UK supplier (David Manners).  This appears to be slightly bigger (maybe a half inch extra diameter for instance) than the original as described here.

The naked end of the exhaust pipe after the muffler came off.  If you click to see the bigger version you can see some collateral damage on the underside and coming through from the top of the pipe.  Since those will be covered by the end of the muffler, I'm not too concerned.  Given the procedure I'm glad and a little surprised it's not worse.

All the banging broke the rubber pad on the hanger just upstream from the muffler.  I'll add one to my next parts order and replace later. They're cheap - about $5.

The new muffler mounted with the tail pipe at about the 2 o'clock position as it seems it should be according to the MGAGuru.

The new muffler from the wheel well.  The clamp bracket at the left is back in place.  It looks like the hand brake cable now touches or nearly touches the exhaust.  That may be because the upstream hanger is broken although it seems like that will make it worse.  Hopefully the heat on that cable will not be a problem.  So far I can't discern any problem with it dragging.