The Onan Muffler Replacement

[Burtman]

Good Day,

I have removed the failing muffler from the 6000K Onan as its done and am wondering if there might be a known supplier or part# that is helpful sourcing something usable?
I found it easy to source a muffler with the same dimension of mine (13" length 4" diameter side inlet end outlet) however it is a tractor muffler, and I do not consider it quiet enough for our needs. Noticed Onan has a 22" length with a 19" body # 155‑1258.

Might there be a known workaround for this muffler issue??


Thanx

 

[RvRev2]

Applied GMC has one for sale. $126.50

Onan Muffler - (C2010) - GMC Motorhome

We are a major supplier of GMC Motor Home, RV Parts. Serving GMC MOTORHOME owners everywhere.

www.gmcrvparts.com

You will want to cut off the mounting bracket off the old muffler and weld it onto the new muffler.

 

[ScottC]

I found one through Cummins, it is in my build thread page 10. Not sure on availability now.

Thread '1973 GMC 26' Glacier Build'

Aug 17, 2021

Ok here we go, we purchased this coach on Sunday August 1st 2021 just North of Columbus, OH in Delaware, OH. The gentlemen we purchased it from bought it from an Estate about 50 miles from there. The story goes that it was the deceased prior owner's pride and joy and was described as having new rims/tires, rust free painted frame, new brake lines, new macerator pump, new fuel lines, fuel tanks cleaned, painted and new sending units, good glass (no hazing), newer A/C unit, Onan generator not running, interior almost gutted, we will finish gutting it out.

Main issues (this list will get...

• ScottC
• Replies: 317
• Subforum: Build Threads

 

[ScottC]

 

[Christo]

Cummins blew out the inventory of our Onan mufflers a year or two ago for super cheap, not sure if they’ll have anything.

 

[RoadTrippin]

I used the 1551258 on mine. Got it off of Amazon. Had to have the bracket cut off the old and welded to the new. I also used the stainless pipe that Applied had. Have issues with that leaking at the manifold and on some of the welds. Will have to figure out something for that soon.

 

[pvfjr]

I've always wanted to try a motorcycle muffler. Commuter bikes/scooters are incredibly quiet in stock form. If I calculated correctly, the Onan should just just shy of 60ci or 983cc. A liter-bike will turn many times more RPM than an Onan ever will, so I'm sure a muffler off a 600cc or 700cc scooter/bike wouldn't be too restrictive. Any of those with a single muffler that's cylindrical-ish could be made to fit with some custom work, and would be of a much higher quality/technology construction--I'm hoping would result in quieter operation.

 

[pvfjr]

One other thing...
Since the Onan is always turning the same RPM, we have a unique opportunity to figure out what the worst resonant frequencies are, and add in a tuned stub in the exhaust. Advanced exhaust guys will do this if a muscle car suffers from drone at a particular speed. It works well--there's nothing quite like destructive interference to kill waveforms you don't want.

 

[Burtman]

Applied GMC has one for sale. $126.50

Onan Muffler - (C2010) - GMC Motorhome

We are a major supplier of GMC Motor Home, RV Parts. Serving GMC MOTORHOME owners everywhere.

www.gmcrvparts.com

You will want to cut off the mounting bracket off the old muffler and weld it onto the new muffler.

I purchased this after someone went in the back and measured it and it is the same sizing as my OEM one and it is on its way

Not really sure if a longer one would’ve worked better perhaps for spark arresting I don’t know how much one can quiet an Onan down?? however, I do know that a tractor muffler is only gonna make it worse so I will give Jim K’s a try

 

[RF_Burns]

For those looking for a way to mount a muffler, I used a short piece of Unistrut. I used a couple of large worm-gear type stainless hose clamps to fasten the Unistrut alongside of the muffler. Then drilled a couple holes to match the generator muffler bracket to the Unistrut. It's still there 15 years later.

 

[Burtman]

I can see that the GMCRV Parts muffler isn't really a muffler now that I have it in hand, just a Walker 22022 Resonator can so back to the beginning for me. Kinda disappointing really.........

 

[Wally]

One other thing...
Since the Onan is always turning the same RPM, we have a unique opportunity to figure out what the worst resonant frequencies are, and add in a tuned stub in the exhaust. Advanced exhaust guys will do this if a muscle car suffers from drone at a particular speed. It works well--there's nothing quite like destructive interference to kill waveforms you don't want.

Running some of the J pipe stub length calculators for the Onan's 30 hz exhaust it comes to around 118 inches. Unless I'm wrong.

 

[tmsnyder]

I can see that the GMCRV Parts muffler isn't really a muffler now that I have it in hand, just a Walker 22022 Resonator can so back to the beginning for me. Kinda disappointing really.........

Sorry for the laugh, but I had a feeling....

RockAuto has that part for $53, probably needs the bracket welded on.

But it doesn't appear to be a resonator, they are calling it an ag / tractor muffler:

Part Details Page

www.walkerexhaust.com

 

[Burtman]

It's Sore-rite, I was looking to avoid the Walker 22022 as its just a basic resonator tractor can. I get it's an Onan and its going to be only so quiet however compared to an actual muffler of the same sizing I'm going the wrong direction if I were to use it.

Sorry for the laugh, but I had a feeling....

RockAuto has that part for $53, probably needs the bracket welded on.

But it doesn't appear to be a resonator, they are calling it an ag / tractor muffler:

Part Details Page

www.walkerexhaust.com