Getting the Firefly back on the road: exhaust fell apart

[MetroMPG]

So now that the U.F.O. has moved to another home, I'm pressing the Firefly back into service.



The 15 year old exhaust on the Flea is original and only has ~30k kms / ~20k miles on it. And it's also falling apart all at once!

The last time I drove the car (not sure exactly when, but my last fill-up was in Dec. 2011), the front section broke right at the catalytic converter inlet. I kind of knew about that when the hamsters under the hood suddenly got angry loud. And the cat. converter dropped on top of the front stabilizer bar and banged around there to add percussion to the rodent symphony.

So today I was testing exhaust bolts to see which ones I could easily unscrew vs. need to cut off, and I proceeded to bust the middle section at the resonator. It was obviously ready to go.

I've priced the replacement front section with cat (it gives Frank Lee an aneurism every time he thinks about it), so will take a stab at repairing/rebuilding it. That means dusting off the little wirefeed welder.

Haven't decided about the rest of it yet.

Anyone have any opinions (HA!) on a resonator delete? Should I keep it? Pros/cons?

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Photo: Muffler and Catalytic Converter by noricum, on Flickr

[Frank Lee]

Aneurism? Tell me about it. Friend of mine told me what a new Metro exhaust cost and I about messed my drawers. I would have gotten a length of exhaust tube and a muffler and grown my own before paying that much!

[mcrews]

I took the resonator off the InfinitQ45 (I know, we're not exactly talkin apples and apples ) but I could feel the vibration/resonation thru the center consol.

[MetroMPG]

I actually happen to have an intact** front section, which for some reason I saved from Firefly #1:


From: A tale of two Metros - MetroMPG.com

** The only problem being: the cat in that intact section was ruined by the previous owner who ignored a failed O2 sensor / CEL; the car ran rich for months and he burned up the catalyst honeycomb. It was literally spitting chunks of it out the muffler when I got the car.

But at least I have more bits 'n' pieces at my disposal to reconstruct that section.

[MetroMPG]

Originally Posted by mcrews

I took the resonator off the InfinitQ45 ... but I could feel the vibration/resonation thru the center consol.

OK. Well we don't want that! Because then I'd have the 3-cyl "Metro shake" at idle plus resonation in the console/shifter.

[mcrews]

Yeah, the more I think back...it was from the 'pulse' created by the exhaust. It 'harmonic' but it was certainly there. And considering the insulation in the Q.....I would thing it would be more obvious in the 'fly'!

[War_Wagon]

*cough-wet coast parts car is what you need-cough*

[ksa8907]

My intrepid has a center resonator that is 2-1 then a muffler and a second resonator at the rear. A long time ago I chopped the rear resonator and muffler off and the car sounded real good at idle but had a horrible drone. I installed a "glass pack" and no more deafening droning noise and is actually quite tame. I suggest about 18-24 inches of pipe after any sound altering device you use.

[MetroMPG]

Uh oh. That sounds like another vote in favour of replacing the resonator instead of welding in a piece of pipe.

Well, I suppose I can try the repair, and if I hate it, order the replacement part. At least all the nuts & bolts will be fresh & easy to deal with at that point!

[MetroMPG]

It occurred to me to look underneath this lovely specimen...



....which I have parked at the garage (and is slowly biodegrading as it sits). And would you look at that, but there's a resonator underneath that is in decent shape -- probably the least rusty thing under there! Sawzall to the rescue! You can never have enough parts cars.

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Also, I discovered there are only 2 exhaust sections from the factory, not 3. I incorrectly assumed the muffler was on a separate little section, but it's attached to the resonator section.

Anyway, here's the situation:

Top: busted catalytic section, front half of busted resonator section.
Bottom: spare catalytic section (with burned out cat) from Firefly #1.



What the inside of a Firefly catalytic converter should look like:



What the inside of my "spare parts" catalytic converter actually looks like... no catalyst! Take this as a warning, kids, not to ignore that Check Engine light.



So I cut the bad cat off the good pipes and the good cat off the bad pipes, tacked the good bits together, test fit under the car, broke the tack welds by accident , re-tacked, then welded it all up.

Next tack/welding session will be the resonator section, probably on Tuesday. Taking tomorrow off to go play on the river with visiting family.