1948 C-170 muffler / exhaust cracks

How to keep the Cessna 170 flying and airworthy.

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Re: 1948 C-170 muffler / exhaust cracks

Postby n2582d » Sat Jun 06, 2020 5:37 am

Thomas,
The first page of that Service Kit shows the brace to be p/n 0550159. The IPC for the 170B in fig. 50-13 shows two part numbers depending on s/n for that brace, p/n 0550159 and 0550159-5. Both of those part numbers have been superseded to p/n 0550179-1. There's one for sale online here. Preferred Air Parts and KRN both show several in stock. Put any of those part numbers in the search box at the top of this page and you'll find a lot of discussion about that brace.
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Re: 1948 C-170 muffler / exhaust cracks

Postby Bruce Fenstermacher » Sat Jun 06, 2020 11:01 am

Thomas, I easily fabricated this part from 2ft of 3/8" 4130 tube with a .035 wall. bought it from Wicks, their part R3/8X035-41 $4.85ft.
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Re: 1948 C-170 muffler / exhaust cracks

Postby GAHorn » Sun Jun 07, 2020 4:20 pm

tshort wrote:So, the new mufflers have been received and fit up nicely. No issues with the cowl exit.

One issue. The diagram for the Hanlon-Wilson modification references a support bracket. This is #5 in the diagram.

I did not have any bracket / support on the old pancake mufflers. I discussed with Charlie Feld, this is not something they include / fabricate. He thought it might be p/n 0450340-1, which is used on the C-150 system and the C120/140 modification.

What is the correct part here?

Thanks in advance for all the help thus far. I am ready to get flying again!


WHAT diagram? Item 13 of the 170-B IPC, Fig 50 is PN0550159 or 0550159-1 which is made of 3/8” mild steel tube, flattened on ends with a tab welded near it’s center that tab attaches to the front/left carb mount stud, and the flattened ends are clamped (PN 0550157-5) around the tailpipes to get rid of a harmonic vibration which can lead to cracks.
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Re: 1948 C-170 muffler / exhaust cracks

Postby tshort » Mon Jun 08, 2020 9:27 am

I was referring to the service kit diagram, SK 70A51-1 Hanlon Wilson muffler installation 170 & 170A

So, will p/n 0550179-1 work for this application on my C-170?

This stuff gets awfully confusing...
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Re: 1948 C-170 muffler / exhaust cracks

Postby GAHorn » Mon Jun 08, 2020 7:02 pm

tshort wrote:I was referring to the service kit diagram, SK 70A51-1 Hanlon Wilson muffler installation 170 & 170A

So, will p/n 0550179-1 work for this application on my C-170?

This stuff gets awfully confusing...


It depends. The reason I write that is because of confusion regarding the illustrations and PN’s listed with those illustrations.

The SK shows PN0550159. That agrees with early 170B models.
That PN was subsequently re-designated 0550159-1 which fit later serials. Both illustrations (not necessarily accurate) indicate straight braces. The other PNs are for braces with two bends in them.

The Cessna 172 and Skyhawk later changed that PN again to 0550186-1 for later serials, but early Cessna 172/Skyhawks used the 0550179-1... not the -5 which was superceded as -1 per the post above. According to the 172 IPC, that also requires (2) Adel clamps PN 684-3-11-36P.

These issues arise due to reconfigurations of carb inductions etc in later aircraft that use the virtually identical engine setup.

Sorry for not being able to be absolutely clear about this, but the IPCs aren’t clear either. Those IPCs are for factory-original airplanes and are not concerned about people who have earlier airplanes that modify to later exhaust systems.

BTW, Cessna, who claims this part is superceded to the 0550179-1 says that part is called a “tube”, but the SK and the IPCs all call it a “brace”. Who knows what 0550179-1 really is... :roll: .... but it’s really really REALLY SPECIAL because Cessna wants $1,638.35 for it. 8O
It must hold the whole airplane up!

For that amount of money one could make a hundred of them using the description I posed above and the IPC for guidance.
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Re: 1948 C-170 muffler / exhaust cracks

Postby n2582d » Mon Jun 08, 2020 9:52 pm

gahorn wrote: Who knows what 0550179-1 really is... :roll:
In my earlier posting I attached a link to this listing showing a NOS part with an 0550179-1 stamp on it. In the photo the part stands on three points. I can't do this with my brace so it is not an exact match to my part which I assume to be 0550159-1.
s-l1600.jpg
P/N 0550179-1
0550159-1.jpg
0550159-1
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Re: 1948 C-170 muffler / exhaust cracks

Postby GAHorn » Mon Jun 08, 2020 10:34 pm

I can’t discern the “-1” on that first pic... but this thread exhibits some of the issues we run across with sourcing superceded parts on these old airplanes. The Adel clamps are another issue that is overlooked with the SK since the PN’s have been superceded. (No apparent revision on the SK that I know of.)
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Re: 1948 C-170 muffler / exhaust cracks

Postby tshort » Wed Jun 10, 2020 12:28 am

So I got the part from Preferred.

I thought it connected to the brackets at the shroud, but it is too short:

Image

Does it attach down here, with other clamps?

Image

Overall the whole thing seems too short to connect to the exhaust pipes ... ?
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Re: 1948 C-170 muffler / exhaust cracks

Postby brian.olson » Wed Jun 10, 2020 1:27 am

Actually looks correct. There should be a band around each pipe that the support will bolt into.

Here's a photo from a couple months ago when we were working on 62C. You can see the bolt, just barely, from behind the pipe. Sorry I don't have a better photo for you.


IMG_4339.JPG
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Re: 1948 C-170 muffler / exhaust cracks

Postby cessna170bdriver » Wed Jun 10, 2020 1:52 am

Mine attaches to the same bolts that secure the clamps that hold the exhaust pipes to the bottom of the mufflers.
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Re: 1948 C-170 muffler / exhaust cracks

Postby n2582d » Wed Jun 10, 2020 6:06 am

Take a look at the drawing in SL170/172-13 posted here.
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Re: 1948 C-170 muffler / exhaust cracks

Postby tshort » Wed Jun 10, 2020 11:52 am

Thanks all for the pics and links - very helpful!

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