Exhaust System

[Avee8or]

11A is in for its first annual since I purchased it...a few surprises along the way. Tube from L muffler to carb heat box had quite a bit of exhaust residue in it...which led to the discovery that the shroud seals are missing on both mufflers. I now need 4 each 0550157-9 and 1 each 0550157-30 and 0550157-31. Any ideas on where to source? There is also a small crack on the right muffler--any recommendations for welding shop? The crack is on the end of the right muffler, near where the curved exhaust pipe enters. Thanks in advance!

[cessna170bdriver]

I highly recommend Aerospace welding in Minneapolis for the welding. The seals show up in their catalog too.

http://awi-ami.com

[Bruce Fenstermacher]

Varel, the seals aren't really a seal in the way we normally think of a seal. They more or less take up a space but they hardly seal. They are made from a soft lead like material. They lay around the inlet pipes and for the most part space out the baffling from the actual muffler. Many many aircraft are found with no seals. We've had discussion elsewhere how many of us might make our own seals by cutting slices of something like a aluminum pipe.

I like AWI and might turn to them. They have supported our Association in the past and make a quality product. I've also used Knisley Welding Inc.

[Joe Moilanen]

I just sent my entire exhaust system to AWI for scrutiny while I major the engine. I should have a report on their work in a couple of weeks (hopefully a good report).

Joe
4518C

[Avee8or]

Thanks, Gentlemen. I'll call AWI Monday.

[cessna170bdriver]

Varel, the seals aren't really a seal in the way we normally think of a seal. They more or less take up a space but they hardly seal. They are made from a soft lead like material. They lay around the inlet pipes and for the most part space out the baffling from the actual muffler. Many many aircraft are found with no seals. We've had discussion elsewhere how many of us might make our own seals by cutting slices of something like a aluminum pipe.

I like AWI and might turn to them. They have supported our Association in the past and make a quality product. I've also used Knisley Welding Inc.

Yes, the "seals" are probably better described as spacers, but they do cut way down on leakage, and the IPC calls them seals. The material is aluminum.

I recently bought an overhauled right muffler for my late B-model airplane from AWI. Maybe Del can post a photo to give an idea of the quality of their work.

[wingnut]

I'll post a photo tomorrow. AWI does great work

[Avee8or]

An update--my muffler was not repariable, so a new one is on the way from AWI. They thought they had the seals (although at about $150 each including core charge!!) but turns out they did not have any. They are working on PMA for replacements, though.

Looking forward to the "new muffler"...under $500.

In checking logs, I realize they did a repair on my Navajo which burst an exhaust pipe 5-10 years ago. It was good work and has held up well.

[Avee8or]

The new muffler arrived today...looks great for $392.00

There is very little space between intake and exhaust risers...I noticed today that the clamps on exhaust have been rubbing into the intake risers, and there is some noticeable wear on the intake risers. The plane has the later model clamps with 2 rather than 4 bolts. Are there any tricks to getting better clearance?

[Avee8or]

BTW, the new muffler is a PMA'd part, not an overhaul.

[Bruce Fenstermacher]

There is no secret. They are all very close and most have rub wear somewhere. In many cases you will have to fool around swapping clamps and clamp positions just to get the best situation with the least rubbing. And when your done, it will leak. It is the nature of the beast.

[Avee8or]

Thanks Bruce. Another reason to look carefully under the hood from time to time! The thought of a cracked or broken intake riser next to that hot exhaust commands respect....