Muffler Issues

N3474C · Post by **N3474C** » Mon Jan 05, 2004 8:55 am

After a recent carbon monoxide scare I decided it was time to do something about my exhaust system. I took it all off and sent it to Atlee Dodge in Anchorage. He called back a few days later informing me my mufflers were junk and would be over a grand to get them yellow-tagged.

I've looked all over for mufflers that are in good shape, but every time I think I've found a solution it turns out to be a dead end. From my original exhaust system I was able to salvage two of the risers and both of the shrouds. My 170 is a '55 (SN 26517) and I ordered the remaining risers as they corresponded to the drawings in the 170 parts catalog. One set of mufflers that I found locally were about 6 inches in diameter instead of my original 5 inchers and only the left hand side fit anyways. The second set of mufflers I found ended up having cracks around some of the stacks and only the right side fit from that set so I abandoned that thought too.

I've called companies all across the US looking for new mufflers and it seems nobody has them and they have to be made. I have one or two more options in Alberta who I will try and get in touch with on Monday, but there is a thought in the back of my head all the time, even if I get new mufflers will they fit?

Anybody have any insight? Appreciate any help,

Thanks,

Chris

Post by **GAHorn** » Mon Jan 05, 2004 9:05 pm

I've talked to these folks personally. They've been in the business a very long time, and assure me they can produce the entire system for you.
Tell 'em we sent you. (The Int'l Cessna 170 Assoc., Parts/Mx coordinator)
http://www.awi-ami.com/prodexhaust.htm

mit · Post by **mit** » Tue Jan 06, 2004 4:04 am

I bought a complete set thru AVIALL. Spendy but good.

mrpibb · Post by **mrpibb** » Tue Jan 06, 2004 4:16 am

Just got a completly new not overhauled set from Knisely out in calif. He has the faa pma approval to make new systems. My old system was completely gone, nothing was salvageable, except for a couple of the risers. he threw in a set of tail pipes made to the original cessna specs (straight cut)
Vic

Post by **GAHorn** » Tue Jan 06, 2004 8:11 pm

And the price was......?

mrpibb · Post by **mrpibb** » Wed Jan 07, 2004 1:27 am

Oh don't know off hand, my buddy is finishing up the annual paperwork he has the invoice, but if memory serves me correctly I think they were 475.00 a side, that is for new not overhauled. I went with new cause the price was not that much different for overhaul. Plus being new and clean my plane must go faster, right? When I first put them on I thought they didn't fit, but what turned out is that when my a/c went from the flat type to the newer style the cowl exit holes were relocated to close together, so I took mesurements and sent them to him and he was glad to make adjustments, the picture is how it looked when I tried to make them fit through the cowl holes, but now they do, didn't take a pic of that yet.

http://www.sandhillaviation.com/engineexhaust.jpg

His part #'s are K550157-9 for the left and a -32 for the right.
and if you get stacks from him they will be staight cut thats how they were approved I speculate.
Vic

Post by **Bruce Fenstermacher** » Wed Jan 07, 2004 5:10 pm

Vic after looking at your latest exhaust picture I have some observations which you and others might not realize.
I see your right muffler (left side of picture) and main heat shroud are like a later "B" model in that you have a 3" scat tube which enters the front of the heat shroud. The front scat would normally be 2" on '48 thru '52 and on this type of exhaust on an A model and would have entered on the side not the front as your is.
Coming out the rear would be 3" scat but yours is reduced to 2" some how. All of the 2" scat tube with the y connector and the center heat distribution is typical of that found on a '48. Not sure about the '48 but the center heat distribution was an option on the A models.
Also some might not realize that the left muffler which you have is right ( correct) for your type shroud but is not the correct muffler for the earliar shroud with 2" scat. This shroud requires a lip on the front of the muffler like the left muffler to support/seal with the heat shroud at the front of the muffler. Just something to keep in mind if you need a early Hanlon Wilson muffler or replacement.
My observations are base on my experiance. Believe it or not one of the things I've checked closely on every single 170 I've seen is the exhaust and heat components. I've also backed up my observations buy looking in the IPC.
You have a very nice exhaust/heat setup, I'm jealous.
Where did you get your heat shroud as I need to replace mine with the type you have. did you manufacture it?

Post by **GAHorn** » Wed Jan 07, 2004 7:57 pm

Bruce -"Also some might not realize that the left muffler which you have is right for your type shroud but is not the correct muffler for the earliar shroud with 2" scat. This shroud requires a lip on the front of the muffler like the left muffler to support/seal with the heat shroud at the front of the muffler..."

You almost lost me there, Bruce, with the left being "right"...when you mean "correct".

Looking at his left muffler (which is on the right in the picture)...it appears that it IS correct...in that it appears to have the lip. All the left mufflers were the same regardless of serial number aircraft (for those using Hanlon Wilson's.) PN 0550157-9 and they all used the 0550157-15 shroud. (In fact, the earlier sn airplanes used the same shroud left and right. The right muffler and shroud changed at aircraft sn 25373 (a '53 B-model) to the higher capacity cabin heater with the 3" induction hoses.
(I know Bruce already knew this, I was just clarifying it for others. If you get the later muffler/shroud for your right side you'll have to make some minor mods to accomodate the 3" hoses, or you'll have to accept the 2" hose outlet on your right muffler to service your cabin heat.)

Vic,...did Knisely also supply the shrouds for the muffs?

mrpibb · Post by **mrpibb** » Wed Jan 07, 2004 10:01 pm

No-The heat shrouds and risers were the only thing good, the shroud A/C right was reworked a little, my buddy is a pretty good tin knocker. We then put in the oven heat it a bit then applied easyoff, let set and rinsed. Next system we do though we may use AWI to give them a try I haven't heard any bad things about them, we went with knisely because he had jigs to make a new set and send them out quick.
Vic

Post by **Bruce Fenstermacher** » Thu Jan 08, 2004 2:45 am

Thanks George. After rereading my post I made a small addition to it to "correct" that which I had "right"

zero.one.victor · Post by **zero.one.victor** » Thu Jan 08, 2004 5:53 am

I have heard nothing but good reports on Knisely,just don't know how to pronounce it. Is it "nicely",as in "he landed his 170 nicely"?
I like to use RH & LH as opposed to right & left,in describing location on the aircraft. Unless otherwise noted,RH & LH is from the pilot's seat facing forward.

Eric

N3474C · Post by **N3474C** » Thu Jan 08, 2004 9:15 am

Thanks guys for the info,

I ended up buying overhauled mufflers from Aerospace Welding for $325 each. They are very nice and I got it all back together today and should be flying it Thursday. Can't wait!

Actually the wind has been blowing like mad here, turning a couple of 170s and 180s outside sideways (hard to get a tail tiedown in the winter), so I'm sorta glad mine was down and in the hangar.

I'm still somewhat puzzled however why the curved stacks are the same length on my new ones, and in the drawings in the parts manual they are different lengths so they required different risers. I ended up having identical risers on both sides and had to salvage a riser from my old system. I bought a new and longer curved riser going by the parts manual thinking I would need it, but didn't end up having to.

Do I have an older style exhaust system?

Chris

Post by **GAHorn** » Thu Jan 08, 2004 8:48 pm

The IPC shows three different item numbers (2, 24, and 36) for what might appear to be three different curved risers....but they are all identical, and are all the same PN 0550157-8.

logsdon · Post by **logsdon** » Fri Jan 09, 2004 7:48 pm

I have had 170 mufflers repaired and have purchased new ones from Acorn Welding in Edmonton Alberta. They can also supply risers. Not cheap but a reliable firm with good service. I think they have a website.

Joe Moilanen · Post by **Joe Moilanen** » Sat Jan 10, 2004 6:15 am

I wound up with the same problem as N3474C when I ordered all new risers several years ago. I didn't get a curved riser that fit #1 cylinder so I cut the new flange off from the one that they sent me and welded it onto my old riser. Can't remember where I bought them.

Joe 4518C