Buick Riviera Exhaust Leaks

[Adam]

I found the first leak during the drive home. The first time I went WOT, it blew a hole through the rust on the catalytic converter. I patched that with exhaust putty and found some holes in the LH muffler as well. Patched the same way. Fast forward a year, and I've had to re-patch the catalytic converter twice. More recently, rust has further taken it's toll and two of the four nuts which hold the converter to the front pipe have completely rusted away. This has caused what was left of the bolts/studs to pull back through and a massive pre-converter exhaust leak to happen. Can't really drive it this way. Conveniently a couple good whacks with a hammer caused the other two nuts to break away and the converter to come off the front pipe.

So I decided to spend some money on this car and bought a new converter ($147), resonator ($47), some hardware, and rear O2 sensor (an AC Delco replacement was only $35 and I didn't have to fight with anything. The OEM exhaust is fully welded so to reuse the rear Y-pipe, I had to cut it and use a 2" ID connector to attach the stock Y-pipe with the replacement center resonator. I painted all the replacement parts with high-temp header paint to ensure they outlast the car itself.

The first time I fired it up, it was much quieter from the middle of the car, but leaky sounding from the rear. Looks like the exhaust putty had failed on the LH rear muffler and the RH rear muffler had developed a similar issue. This is now patched in the same way, but it is only a matter of time until it fails again. Especially since I can now use WOT w/o worrying about the converter patches failing. Conveniently, the Walker direct replacement mufflers are not currently available from anywhere. I could use the Aurora mufflers instead (same pipe size but different tip style), but only one side appears to be available anywhere.

Oh well. I'll just wait longer. I could use a universal muffler and try to salvage the OEM tailpipe, but those contain a required hanger and are in questionable shape anyway. I did find some NOS OEM mufflers, but they wanted $300+ each, which is too much. If it gets really bad and there is still no direct replacement, I could probably make something from universal mufflers and some 90 and 45-degree pieces and weld on something for the hangers.

Walker replacements for reference:

riviera_lh_muffler.jpg

riviera_rh_muffler.jpg

[Adam]

Anyone ever heard of these guys:
http://www.apemissions.com/

They make stuff for the Riviera, are sold on summitracing.com and have a hilariously dated-looking web catalog.