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Discussion Starter #1
What have you folks with Onan B43/48M engines used for replacement mufflers?

I just realized, after pulling off what was left of the mufflers on my 8163-T, that the ones I got don't fit... Gravely P# 18543 has an inlet ID of 1-5/16", but the Onan mufflers had a 1-1/4" inlet/header pipe. I have yet to locate any mention of P#23299 by any retailer, including Richards and Jack's small engine.

I know I've seen other discussion of mufflers, but don't recall any mention of this particular detail... a quick search doesn't turn up anything for adapters of that size, either.

Stickman
 

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The last time I bought mufflers for my B48 I got them from Gravely. I had to buy the whole thing since it had corroded away. It has been a long time and stock may no longer be available.

I see that an Onan adapter pipe is still available but likely wont help you. $25

The 154-1484-50 Adapter Exhaust Manifold has the following dimensions:
flange bolt hole centers - 2".
Pipe that extends into block - 1.200" OD.
Top of external pipe is 1.500" OD 1.390" ID.

Uses 154-2747 Exhaust Gasket.
 

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Gravely bug bit.
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The ones I've bought were either Nelsons or from Stens. And they always fit.How are you mounting them. The inlet is the side hole on an Onan while it is the end hole on the Briggs and Kohlers.

105-262
Muffler
GRAVELY
018543
Length: 8"
OD: 3 1/2"
1 1/4" ID outlet
1 5/16" ID inlet

And now for why you can't find the # 23299.
Part Number: 20401600 MFLR,816T & 818T Product ID: GRAVELY
Qty Required: 1 Qty Available: 0
List Price $: 237.45 USD

Discount Code: Stocking Code: 0 Service Status: X Standard Pack:

Location Available
 

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Discussion Starter #4
The ones I've bought were either Nelsons or from Stens. And they always fit.How are you mounting them. The inlet is the side hole on an Onan while it is the end hole on the Briggs and Kohlers.
Yep, I've got the 18543 mufflers, which have the 1-5/16" inlet on the side. The header pipe is 1-1/4" OD, though, so the mufflers only fit backwards. Replacing the pipes might be an option, though I'm not sure how a 1.5" OD will help in this case.

My consolation at this point is that it's not really much louder without mufflers than it was before I took them off...

And now for why you can't find the # 23299.
... List Price $: 237.45 USD
Because nobody would pay for them? :dunno: ;)
 

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Old Iron Connoisseur
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When I put new mufflers on my B48 I just tightened the clamps til snug. It will crimp the muffler but it works.
 

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If your header pipes are salvageable, just cut the mufflers off and bend some pipe and clamp that on. You can run whatever muffler configuration you want then.
 

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Discussion Starter #9
If it doesn't work, you could always put it on your K301 or Briggs 16 HP engine.
I'll get right on that, is anyone giving away a Briggs? :D

I decided to just crank them on like Jimmy suggested and that works. I really hate exhaust leaks and was hoping to avoid that option, but it's better than I thought it might be; certainly not bad enough to justify spending more time and money on right now, and still quieter than the Kohler Pro-16 I ran last winter. (That tractor needs a :loud: smiley with earmuffs.)
 

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I am going to be making a simple exhaust system for my 24hp Onan and will post the results. I hope it will look and sound like my 818T exhaust.

The exhaust flanges for the B48 and the P224 are the same.

Here is a movie of me horsing around with the 818T engine.

http://rich.homeunix.com:443/gravely/engines/onan/DSCN5751.AVI
 

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RICHARD
it is late, but i must reply here.
Big block and small block exh. flanges are NOT the same.
thank you. boomer (the used onan engine parts guy)
I guess the P224 and B48 are different? The flange measures the same on both engines...2" center to center on the bolt holes. They also share the same part number for the gasket.

The CCKA exhaust flange is smaller.
 

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I think I figured out what this PO's problem was with this engine and why he took it out of service. He had a spark arresting RV generator muffler on it and he failed to keep it clean. He could not clean it as the cleanout plugs are pointing up to the sky.

As a result, it is clogged causing all manner of excess back pressure. That explains the low level of exhaust volume from the engine when I started it yesterday.

I will be removing the muffler tomorrow and will be temporarily putting on something that might not be clogged.

Some of the PO's exhaust work.



 

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I think I figured out what this PO's problem was with this engine and why he took it out of service. He had a spark arresting RV generator muffler on it and he failed to keep it clean. He could not clean it as the cleanout plugs are pointing up to the sky.

As a result, it is clogged causing all manner of excess back pressure. That explains the low level of exhaust volume from the engine when I started it yesterday.

I will be removing the muffler tomorrow and will be temporarily putting on something that might not be clogged.

Some of the PO's exhaust work.



You'd be surprised how many 2-cycle units come in with clogged exhausts. Pull the screen and burn the carbon off and they run like new.
 

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You'd be surprised how many 2-cycle units come in with clogged exhausts. Pull the screen and burn the carbon off and they run like new.
A clogged muffler sure makes the engine quiet. It doesn't do much for the power though.:ROF
 

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I am making a no-weld exhaust system for my P224 engine that is going on my 16G. The P224 has the same exhaust port as the B48.

So far what I have ordered is the following.

2 pc - Onan 154-1484-50


Onan exhaust header

Cost is about $25 each

Next is two gravely mufflers. Cost is about $30 each



Gravely muffler

Then comes the 1-1/4" OD mandrel bent tube.

It looks like this:



Cost is about $22 each in stainless.

I made one piece of tubing today as an adapter between the Onan header and the 1-1/4" mandrel bent tube. I will be picking up a piece of tube from my local steel supplier. The tube dimension is 1-3/8" OD x 1-1/4" (1.245) ID

A few 1-1/4" and 1-3/8" muffler clamps from McMaster should finish the job.

There it is. One complete exhaust system for a Onan B48/P224.

When I get it all put together and installed I will post picture of the completed exhaust system.

Why did I use tubing instead of pipe? Pipe just doesn't work for this due to the dimensions involved. Pipe is not very attractive either.
 

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Richard-

I'm excited to see your completed exhaust. I'm guessing you are looking to go something similar to an 818T or 8183-T with twin Nelsons. Where did you find your 1-1/4" mandrel bend pipe? Was it local or mail order? I've been wanting to build a custom muffler for my B48 that is more like the older CCKA muffler of the 816 and knowing these part numbers will make it much easier to do.

Also does anyone know what the internal routing of a CCKA muffler looks like. I have an idea but not 100% sure.
 

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Due to my not needing a muffler yet, I have not directly investigated a muffler.

But, there are two things I would try/look into.

Try: A guy took the muffler off his Cub Cadet Quiet Line. The neighbors complained. So he took the muffler the QL came with, cut the end off, gutted it, and lined the empty muffler with muffler cloth and wire mesh, then reattached the end.

He says when running at load it is actually quieter than the muffler with baffles. And the machine is "throatier" at idle and no load.

That sounds like a win - win.


Look into: I have not seen where someone has used motorcycle baffles to build an exhaust. Lot of those components look good, are the same size as our muffler needs, and are mass produced.
 

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As far as my intent goes, here are my requirements for the 24 hp Onan exhaust project.

1 - weldless if possible - I wanted to make this so that the average fellow can do this. Almost all of this info can be directly applied to other engines like the Magnum.
2 - no pipe fittings. Pipe fittings look unprofessional at best.
3 - low cost.
4 - reasonably quiet
5 - tubes to be of stainless steel if possible

I refuse to get into muffler modifications for a "better" sound. To me the quieter the better. The quiet mufflers are the large RV Generator mufflers but with that comes a large size, significant expense, and additional maintenance.

The sound of the 818T is very nice to me although it could be quieter.
http://rich.homeunix.com:443/gravely/engines/onan/DSCN5751.AVI

Anytime a two into one exhaust is involved, the cost usually rises by a factor of 3 or more so a dual exhaust is usually cheaper. In my case, the backpressure presented to the 24 hp Onan could be substantial if the wrong muffler were used. The 24hp Onan will produce about twice the amount of exhaust flow of a K301.

The problem with rolling-your-own muffler designs is that back pressure and DB measurements are almost never done. Without those data, it is all perception and subjective.

I considered using the Cub Cadet long muffler but the inlet pipe diameter is wrong. That muffler is made to slip over 1" water pipe. While that makes it easy to put that muffler on a k301 two wheel tractor (an excellent upgrade BTW) I feel it is not appropriate for this project.

I considered a two into one with a RV muffler, but that would easily triple the cost and the amount of work involved not to mention the size of the muffler. That would also mean that a larger discharge pipe is needed to maintain the back pressure that dual exhaust provides. I figure a 1.75 diameter pipe would be needed.

When I am done with this project I will likely replace the exhaust on my B48 since the mild steel pipes are corroding badly.

My personal opinion is that the muffler commonly found on the CCKA engine is a kind of RV generator muffler. The silly things last a very long time and are pretty quiet.
 
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