Exhaust Stack leaks
Posted: Thu Jun 26, 2003 2:54 am
I am looking for ideas on how to stop the exhaust leakage at the joint between the exhaust stacks and the short pipes rising out of the H & M style muffler.
The International Cessna® 170 Association
Formed to preserve and promote a truly classic airplane
https://forum.cessna170.org/forums/
Exhaust Stack leaks
Page 1 of 1
Posted: Thu Jun 26, 2003 9:40 am
wrap a strip of stainless steel shim mat'l around the joint, under the clamp. iirc, 0.003" works well.
Posted: Thu Jun 26, 2003 3:04 pm
and then, George's suggestion of WallyMart's Aero muffler tape around that is easy to use and works very well. It finishes the job of sealing whatever small openings are still left. It looks permanent after the heat from the engine melts it on, but a little heat applied to it will make it easy to remove on exhaust dissassembly when needed.spiro wrote:wrap a strip of stainless steel shim mat'l around the joint, under the clamp. iirc, 0.003" works well.
Exhaust Stack leaks
Posted: Fri Jun 27, 2003 12:46 am
Thanks for the replies. Spiro where do I buy stainless steel shim material?
Posted: Fri Jun 27, 2003 1:20 am
I first used the stainless steel foil (found at True Value hdwr in the hobby section) last year, but found it didn't really seal all that well, durable tho' it was.
The muffler tape was the suggestion the Cessna service center suggested and I thought they were kidding, until RAM and Air Impressions in Waco both said that was the fix used on RAM conversions.
I used the muffler tape, and no more problems.
The muffler tape was the suggestion the Cessna service center suggested and I thought they were kidding, until RAM and Air Impressions in Waco both said that was the fix used on RAM conversions.
I used the muffler tape, and no more problems.
Posted: Fri Jun 27, 2003 9:09 am
I get that SS shim mat'l at my local bearing store. Same place I get seals, like for accessories.
I've got a few old trucks patched together with various muffler bandages and tape, so I'm familiar with those products as well. I think George is talking about the metal foil tape w/ adhesive backing. I've never used it on an airplane because it appears to be mostly paper w/ a very thin foil of metal. The shim mat'l is much more substantial, although it does need to be very thin to conform well. You could probably use 0.001" and it'd still be a lot thicker than the foil on that muffler tape.
I've got a few old trucks patched together with various muffler bandages and tape, so I'm familiar with those products as well. I think George is talking about the metal foil tape w/ adhesive backing. I've never used it on an airplane because it appears to be mostly paper w/ a very thin foil of metal. The shim mat'l is much more substantial, although it does need to be very thin to conform well. You could probably use 0.001" and it'd still be a lot thicker than the foil on that muffler tape.
Posted: Sat Jun 28, 2003 2:54 am
Nope. I'm talking about a 1-1/4" wide, red colored fiberglass-type of tape that is made by "Victor" and sold at WalMart, AutoZone, and at NAPA.
Posted: Sat Jun 28, 2003 6:44 am
George, I never heard of this exhaust tape. But I will get some for my toolbox ....170MB 
Posted: Sun Jun 29, 2003 2:28 am
Do you put the muffler tape on under or over the clamp?
Posted: Sun Jun 29, 2003 4:37 am
Beneath the clamp.
Posted: Sun Jun 29, 2003 10:37 am
George, as I recall, you said to apply the tape, run the engine to heat it up and let it cool- could you please verify ?
Rudy
Rudy
Posted: Sun Jun 29, 2003 7:08 pm
Well, ...you really have no choice, because eventually you'll run out of fuel. 
Seriously tho',...
You should wrap the joint, install the clamp, and run the engine to operating temperature. In other words, more than simply idle the engine because the tape actually "melts" and seals the joint. I suggest letting it cool and harden rather than blasting off onto a long trip (which would keep it under pressure while initially softened) in order to let it "carbonize" into a hard seal rather than remain melted, pliable, and run the chance of it not having a chance to seal by letting a bubble of exhaust escape and make a pathway for future leaks while still soft.
The material appears to melt and carbonize into a fiberglass type of sealant. It should be removeable in the future by simple disassembly of the joint, as the fiberglass epoxy will shatter and crumble upon disassembly.
I've flown mine about 30 hours since I did it, and it's holding up well, with no leaks whatever. Previously, there was always a bit of exhaust which escaped the clamp/joint area and blown on adjacent engine parts, but no more.
Seriously tho',...
You should wrap the joint, install the clamp, and run the engine to operating temperature. In other words, more than simply idle the engine because the tape actually "melts" and seals the joint. I suggest letting it cool and harden rather than blasting off onto a long trip (which would keep it under pressure while initially softened) in order to let it "carbonize" into a hard seal rather than remain melted, pliable, and run the chance of it not having a chance to seal by letting a bubble of exhaust escape and make a pathway for future leaks while still soft.
The material appears to melt and carbonize into a fiberglass type of sealant. It should be removeable in the future by simple disassembly of the joint, as the fiberglass epoxy will shatter and crumble upon disassembly.
I've flown mine about 30 hours since I did it, and it's holding up well, with no leaks whatever. Previously, there was always a bit of exhaust which escaped the clamp/joint area and blown on adjacent engine parts, but no more.