Get a can of PB Blaster penetrating oil. Spray the nuts under the manifold and the cat flange genereously, let it sit, and do it again. DO this several times, even for a few days before starting the project (NOT ON A HOT ENGINE!)

The nuts at the flange are 16mm and gave me an opportunity for using my 16mm deep socket for something other than keeping the 15 and 17mm ones apart in the set. A long extension will make life easier (18 inches or so). Mine have come right apart without ill effects but I could be the exception. Those copper flange nuts from the dealer are a requirement. Also use Never-Seize on the threads when reassembling. Get a new flange gasket from a parts shop ahead of time. Remove a couple of the rubber hangers at the front muffler if you can't get enough movement out of the exhaust to get it apart. I'd recommend breaking the catalytic converter flange nuts before taking the manifold nuts off.


As with any exhaust work, be patient, and don't force anything that doesn't want to come apart. Good luck.
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 808K total