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Muffler Cracks


sandpiper

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Yesterday, while completing my annual, I noticed there was a failed weld in the angled support bracket where the #3 cylinder (right rear as viewed from the pilots seat) exhaust pipe goes into the muffler. Then, on closer inspection I verified there was also a slight crack in the muffler body running about 1/2" towards the front of the plane. This was almost invisible and at first I thought it was a scratch. So, with hints from Roger about how to get the springs off without doing major damage to knuckles, and with purchase of a new tool, off it came. Once off, it was obvious the crack also traveled about an inch toward the center of the muffler and that the weld around the base of the inlet had a 270 degree failure. To be more specific, looking down at the muffler inlet for #3, starting about an inch north of the 12 o'clock position the crack traveled to the inlet circumference weld, traveled counter clockwise around the base to the 3 o'clock position, then traveled east toward the front of the muffler 1/2". Should have taken pictures before the repair but didn't.

 

So, had it welded and now time will tell.

 

Next time you have your cowl off, look carefully at your muffler. Use a mirror to look behind the inlets. Make sure your mechanic does the same when it's in for service.

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Yesterday, while completing my annual, I noticed there was a failed weld in the angled support bracket where the #3 cylinder (right rear as viewed from the pilots seat) exhaust pipe goes into the muffler. Then, on closer inspection I verified there was also a slight crack in the muffler body running about 1/2" towards the front of the plane. This was almost invisible and at first I thought it was a scratch. So, with hints from Roger about how to get the springs off without doing major damage to knuckles, and with purchase of a new tool, off it came. Once off, it was obvious the crack also traveled about an inch toward the center of the muffler and that the weld around the base of the inlet had a 270 degree failure. To be more specific, looking down at the muffler inlet for #3, starting about an inch north of the 12 o'clock position the crack traveled to the inlet circumference weld, traveled counter clockwise around the base to the 3 o'clock position, then traveled east toward the front of the muffler 1/2". Should have taken pictures before the repair but didn't.

 

So, had it welded and now time will tell.

 

Next time you have your cowl off, look carefully at your muffler. Use a mirror to look behind the inlets. Make sure your mechanic does the same when it's in for service.

 

Hey Sandpiper--Like you say time tells....How many hours on the engine? How many months since last annual? Thanks Doug

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Hi John. Just now putting things back together after the rubber change but still have the cowls off. I'll look at my muffler. Thanks for the heads up. Although you've already had your muffler welded, just wondering if a picture of the welded and repaired muffler might show us where the cracks were?

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It's back on the bird. But, picture this. You are sitting on a stool on the right side of the engine lookong from the right side of the muffler to the left side of the muffler. The cracks were around the rear (#3) exhaust inlet to the muffler. The crack ran from 1/2" out from the 3 o'clock position, into the base weld around the base of the inlet, traveled clockwise around the weld to the 12 o'clock position, then out toward the left side of the muffler for an inch. So, the original weld failed around 3/4 of the base plus it cracked into virgin territory at noon and 3 o'clock. In addition, the little brace tack welded to the outside of the exhaust inlet to the muffler had a failed weld on one end.

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