180 Exhaust System problem

[John Wedge]

On arrival at OSH last week I found that the 1962 180's exhaust system had developed several problems. Only prior problems have been a broken weld on two exhaust stacks over 26 yrs. Unable to understand what caused this to occur and home mechanic suggested a post here. Prior to trip acft had new top half of carb heat shroud assembly installed with two new attachment brackets fabricated and new Lord mounts installed. Acft flew about 25 hrs prior to trip - everything great and engine runs very smooth, smoother than it has in all 26 yrs except maybe right after rebuild in 1984. Entire trip to OSH very smooth operation. Problems: Crack developed in weld where carb heat shroud barrel (for lack of proper name) is welded to exhaust pipe, new aluminum top half shroud assembly edge rubbed ragged where it rests on the "barrel", one new bracket attaching the top half shroud was broken (appears stress cracked), muffler "appears" to have moved to the left about 1/4 inch and now has slight exhaust gas leak at the muffler bushings on each end. 180 exhaust has no support bracket at back, muffler, tail pipe etc all supported by attachment of pipes to engine. No cracks at stacks. It is obvious there was a lot of vibrations in short time - about 3.5 hrs as this occurred after mid trip fuel stop as all was checked then and no evidence of any problem. However there was no unusual vibrations felt at any time during flight. Have not removed system yet to check on pins for muffler. Has anyone experienced something like this or know cause for it? Is there any "approved modifications" for a support bracket to perhaps mount from muffler to rear of engine? Your thoughts / advice would be appreciated.
John

[Chris Kuyoth]

[Zach Grant L1011jock]

[John Wedge]

[DAVEG24]

[John Wedge]