1977 GMC Palm Beach

Our resto-mod RV, 2002 to present

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Onan Muffler

The $65 Onan Muffler and Down pipe

Couldn't pay the $350 for the Onan muffler and down pipe...

August 2003

Approximate Price for all parts: $65

Oct 2013 Update: Current price for all parts is approximately $150

Based on current pricing, I would recommend Onan specific parts that are readily available from Applied GMC, GMC Coop, and others. Also check ebay for many suppliers.


I went to Cumins-Bridgeway and had them look up the muffler and down pipe. They said the price was $79 for the muffler kit but the down pipe was $75. I took the muffler and went on my way hoping the Mountain Dew can was covering a broken muffler fitting not the down pipe. Well, I was wrong and so were they. Upon opening the box I found a completely different muffler from my old one. I went back a few weeks later after a vacation with the Mountain Dew can working fine and a few extras in the fridge. "Oh, you have a power drawer?... I remember you told me that Mike... I bet I looked up the wrong number." Yep, the guy remembered my name from two weeks ago and he looked it up again. He sat back in his chair, hands over his head in astonishment... "That one lists at $285 and the down pipe is $72... maybe you should stick with the Dew can!" Well I went on a scavenger hunt instead and he kindly wished me well and said to come back if I needed help... Nice guys stuck with a price gouging supplier.

Very long story shortened, I found a muffler at Napa distribution warehouse, an elbow, and had a pipe bent at Aarrow Radiator and Glass. I highly recommend the Napa warehouse on SR161 East of Sawmill Rd., very helpful and if it isn't in the warehouse, it isn't made! Also Aarrow Radiator and Glass on Hayden Run West of Cosgrey... good ole boys that still love to work on things and the harder the better. These are the same guys that built my 52 fin radiator on the previous page. Matt is the pipe bender and A/C mechanic... more on that on another page later.

There were problems with this installation... basically, you can't get pipe or mufflers in less than 1 1/2 ID. Our Onan down pipe flange is 1 1/4 ID at the manifold. I gave up looking for 1 1/4 and got it in 1 1/2. I then cut a two inch section of the old pipe (center part that was still good) and stuffed it into the new pipe. I then stood the pipe in a vise and cut 4 slits like the original to fit the tapered manifold flange. I coated the inside surface with high temp rtv since the old pipe was rusty and might not fit tight. I used the old clamp with a new bolt. Don't try a muffler u-bolt, the flange is cast and the u-bolt requires both inside and outside pipe to squeeze with the clamp for tight fit. The 1 1/2 pipe was flanged/stretched to a 1 3/4 on the muffler side. Muffler and elbow are 1 3/4".

After getting this all on, I found a web site on building emergency home generators out of just about everything. They were all saying how great using a car muffler because they are so quiet. Then I found a convertible car club page on the car muffler they were recommending and they were all complaining about the loud mufflers (don't remember which car, some small foreign). They solved the problem with a motorcycle baffle from JC Whitney. So to quiet this down, may try one of them... about $5.00.

In the end, this is quieter than the OEM muffler... don't know about the $285 new version... for that price I think they actually just follow along with you and charge your batteries whenever needed so you don't hear a thing.

Muffler Part number: 22769, $49.55
Elbow: 41000, $5.86
Pipe from Aarow: $10 cash
Clamps: $3.00

Note: I do see that you can get a stainless bolt on replacement from Golby. I would recommend this if you want the quality and a direct bolt on. I just wanted to see how cheap it could be done well for a suitable replacement.

While I was at it, replaced the plugs, oil filter and filled with Mobile 1 15w50.

To see a detailed list of parts and prices go to http://teamteets.org/GMC/expenses.htm and look (later) under job name "onan muffler".

New down pipe... old clamp, new bolt

New muffler with 1 3/4 inch inlet and outlet. HEY, stop laughing at my welding job! I am a computer guy for gosh sakes, I can't figure out how to make the bytes coming out of the welder lay down on the recording surface! I welded a plate on the side of the muffler to match the original. The 1 3/4 inch elbow was cut down as much as possible on the muffler side to keep it short.

Here is the new baby tucked safely in its new home. Maybe a chrome tip from walley world would dress her up!

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About the Author: Mike Teets is an IT Innovation Consultant, Father of 3, outdoor sports enthusiast and builder/restorer of things
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