Exhaust muff spacers

[Thart739@gmail.com]

Hello everyone. I am looking for two spacers that go around the exhaust pipe at the top end of the muffler. They are a spacer that the muff rests on. I found one in pieces yesterday when I was investigating why my cabin heat flapper was stuck open. Has this ever happened to anyone? I was also wondering if I could get along without them?
Thanks,
Travis Hart
48 170

[Bruce Fenstermacher]

Travis, you are talking about what looks to be a lead or some other soft metal donut that rest on top of the muffer under the heat shroud and seals the heat shroud. Or at least it is suppose to. And we are talking the round Hanlon Wilson exhaust system.

If this is the part you can get by without them until such time as you find a suitable replacement. You can not buy these unless AWI has decided how they are going to make them.

We've discussed this but it's been a while. If I was going to make them I'd hunt for a soft aluminum pipe of suitable inside and outside diameter. Then I'd cut this pipe into slices the appropriate thickness. Last I'd bend these slice to shape to lay flat on the round muffler.

Another way might be to find very thin dead soft aluminum sheet and rolling it like a cigarette. Then cutting the rolled aluminum to length that will form the O.

You might also consider soft lead sheet and do the same. I'd also consider melting wheel weight lead and pouring it into a mold you would have to make out of something the molten lead won't melt. You'd probably have to carve this a little with an die grinder. And of course being lead you don't want to inhale the dust or eat any. I'd also want to consider if I wanted any lead in the hot air duct I'm breathing which is why I suggested aluminum first.

[Thart739@gmail.com]

Thanks Bruce I like the aluminum pipe idea I think that might be my best option.
Travis
48 170

[T. C. Downey]

More better ---

find your local fire place or free standing stove supplier, get a stove gasket (Fiber glass rope) and a tube of fireplace gasket cement. wrap the gasket around the standing pipe cut it to length and glue it there, add the muff over the whole sticky mess. when it gets hot the gasket cement will harden in place. it'll last a long time with no leakage.

[Bruce Fenstermacher]

More better ---

find your local fire place or free standing stove supplier, get a stove gasket (Fiber glass rope) and a tube of fireplace gasket cement. wrap the gasket around the standing pipe cut it to length and glue it there, add the muff over the whole sticky mess. when it gets hot the gasket cement will harden in place. it'll last a long time with no leakage.

This is another excellent idea Tom, I like it.

[Metal Master]

A part is available from Cessna for the top of the muffler. It is listed for the Cessna 172 serial number 17247747 through 17247747 which had a O-300D in the aircraft I was working on. They are made from soft aluminum tube. Part number 0550176-22 They list for $220 and sell for $161.60. I purchased them for a 172 customer a while back and they are the same as the ones installed in my 170A. They do not have a listing for the bottom one that I can see. In the 172 installation they also have "packing" part number 0550176-45. listed as a seal on Cessna parts.com. It is a glass fiber type rope probably used to be asbestos. The packing is supposed to pack between the riser and the seal/ I do not believe the seal was used on the 170A. But it is not a bad idea on the cabin side muffler. I tried and could not get the packing installed in my Hanlon Wilson muffler. Probably just need to try harder. I have been meaning to try and find some soft aluminum tube of the correct diameter and make some.

[Bruce Fenstermacher]

They are made from soft aluminum tube.

I might disregard the lead suggestion. I was trying to think outside the box for a soft readily available material. We are trying to duplicate the aluminum and the best way to duplicate aluminum is to use aluminum.

[GAHorn]

yep. Lead melts around 600 degrees and exhaust run in the 1000 or greater range.
A bit of "firesleeve" for 1/4" or 3/8" hose might be shaped into a doughnut, safety-wired together at ends, and used.
But except for a small loss overboard...it is not necessary to have the seal at all.

[Bruce Fenstermacher]

yep. Lead melts around 600 degrees and exhaust run in the 1000 or greater range.

Aluminum can melt at 865F depending on the alloy.

But I hadn't even considered the exhaust hot enough to melt lead. Another reason it might not works so well.