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Has anyone rebuilt or build from scratch a muffler for the Onan P series engines?? I ask, because where I volunteer we have (gifted to us) a Timbermizer Band Saw Mill with an Onan Performer (24 HP??) engine with a bad muffler. I have a 318 with a p218g. Could I salvage the 2 exhaust pipes coming from the engine and build a new muffler with thicker material using the existing pipes. Hopefully the baffles inside have not rotted away and I can use the old muffler for design information.

A new muffler from Cummings Onan is $360.

Thanks for any and all help
 

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If you can cut, drill and weld, a new muffler isn't too hard. Do a search on this site for "muffler design". you will see the inside of a honda muffler plus a box design by some one else. The onan should be similar to the honda.

The tricky part will be welding the old pipes (or even new pipes) to the muffler. I did the initial tack welds while the pipes were bolted to the engine so I could get everything aligned. I then took it off and did my final welds. Things moved with the heat of my final welds, so I had to heat things up with a torch and twist and pull and beat a little to get back to good alignment. My muffler and pipes were pretty hefty, so I didn't want to be straining the aluminum heads by forcing the muffler to match up by bolting tight - so good alignment was important to me.

Depending on your needs for originality, it would be easiest to run the two pipes off the engine to independent mufflers (dual exhaust)
 

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Tractors are Red
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Here is a couple pictures that may help you, or least an idea.
The engine is a 18hp Vanguard, sorry not a Onan.
The muffler started with a Walker 24442 glass pack resonator, made several cuts, remove center section, and cut one end.
Leaving one section with half the outer jacket and the perforated inter tube complete. The other outer jacket being empty, using a 1 inch hole saw to facilitate the exhaust opening.
Installed a 1 inch tail pipe connector from the inside. Used 2 of 1 inch black iron 90 degree elbows, 2 short 1 inch black pipe nipples, and 1 inch seamless steel tubing, for the inlets.
Reuse the fiber glass packing.
After cutting out 2 mounting flanges, a dry fit up on engine, tack welded the pieces while the assembly was mounted on the engine. Remove and finish welding.
An inexpensive muffler.
 

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Yeah, I did the same when I repowered a zero turn with a B&S engine, and the B&S exhaust I bought with the engine needed to modded to fit in the frame. Cut the exhaust off the engine, so there was a short piece of exhaust pipe sticking out of the flanges that bolt to the engine, then cut bits of tubing cut at angles and tacked them in place to get the muffler in the right spot, then welded everything up.

It's the only way I can weld anything that needs to be in a precise spot (it has to be bolted in place or clamped very firmly to something), otherwise it's just "about there".
 

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Q: How was copper wire invented??

A: Two guys in Maine fighting over a penny.


OP - You've been given a saw mill and won't buy a new muffler? Spend the money and be glad you did.
 

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Make Better Mowers
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Several years ago, before I got into Cub Cadets and John Deere's, I had a Snapper twin cylinder Briggs with 54" Deck. I disconnected the muffler and went with dual stacks for a custom sound. It was wicked but loud. When I sold it to a neighbor, he brought to back to me wanting to quiet it down some. Good thing I didn't toss the original muffler!
 

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Make Better Mowers
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I've had some pretty substantial mufflers develop leaks......particularly at welds. If you ever have this situation, I've found brazing to be quite effective in sealing up these small leaks. The muffler I'm using on my 1994 LX178 (original muffler) is one that had two leaks......one at each inlet pipe. I've probably put on 300 hours or more with the brass still takin' care of business.
 

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Discussion Starter #9
Q: How was copper wire invented??

A: Two guys in Maine fighting over a penny.


OP - You've been given a saw mill and won't buy a new muffler? Spend the money and be glad you did.
My budget on any project at the Museum starts with $0.00 and quickly goes negative from there. That is why I am trying to find info on building one from scratch. Between the dozen or so of us who do the problem solving and building things, we have all the skills , that when combined, we can make do or remake a make do.
 
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