muffler 4905

blue4905 · July 23, 2007, 10:50:34 PM

does anyone know if I can still buy a new muffler for a 74' 4905 ? or do I have to build one? any suggestions?

TomC · July 24, 2007, 07:23:04 AM

You can buy the same muffler, but I wouldn't. It is really stuffed up with a 3 inch outlet. Since I turbo'd my engine, I bought a Donaldson 5" inlet and outlet on the same side muffler that really opened things up. Plus the bus now has a nice exhaust note where you can actually hear the engine, up and beyond the Diesel noise. I believe that muffler would work for you also. Good Luck, TomC

TomC · July 24, 2007, 07:53:25 AM

The muffler I used is a Donaldson M120131, 5" inlet and outlet on the same side, 30" long, 10" x 15" oval. Granted it is a low back pressure muffler for turbo, but can use it on non turbo. It isn't a real quiet muffler, but I like to hear some engine sounds. Good Luck, TomC

FloridaCliff · July 24, 2007, 05:14:14 PM

Blue,

You can get a new manufactured stock muffler through Luke for around 1000.00 to your door.

The muffler is a major hazzard on a 4905, just a few inches from a wood floor.

After mine blew a hole and almost caused a major fire

See: http://www.busconversions.com/bbs/index.php?topic=1218.0

I replaced the stock muffler with a set of duals.

The R&D costs were around 800.00 to me, but the actual parts ended up around 600.00

Basically I removed the stock muffler, 90'ed both inputs down, added a piece of 3" pipe, 90'ed to opposite sides, muffler, downpipe.

The trick is you have to leave one of the input pipes to he old muffler longer so you can bypass each other as you go to the opposite side.

The mufflers are oval and just match the shape of the arm in the radius rods.

They are supported in two places each by flexible hangers to allow for movment.

Just another idea!

Cliff

FloridaCliff · July 24, 2007, 05:22:40 PM

Heres a shot of the installed mufflers

Cliff

blue4905 · July 24, 2007, 09:10:08 PM

Thanks Cliff, thats the best looking set-up I've seen yet, you wouldn't know the lenth of the muffler body would you?

TomC · July 24, 2007, 09:24:01 PM

WOW $1000.00 for a Muffler? Someone is getting rich. My muffler was $175.00 plus another $200 in fittings. Good Luck, TomC

Barn Owl · July 24, 2007, 09:35:36 PM

I have taken 55 gal drum metal and re-skinned mufflers before. I just welded it over what was there (old skin), not just a patch, the whole thing. It looked new and heavy duty when I got done with it. I didn't do this for a bus, but I don't know why it wouldn't work. From the looks of my 4106 muffler I will be doing it sooner than I want to. When I do I will post photos of each step. It's not hard if you can weld. I would think that it would be very inexpensive compared to new even if you had to pay someone to do it.

TomC · July 25, 2007, 08:19:34 AM

The problem with "skinning" over the rusted outside, is what is the condition of the inside and the baffles? If a baffle in the muffler comes loose it can effectively block the exhaust route creating lots of back pressure. And with the blower doing the work of getting the exhaust out, can create all sorts of problems-like blower failure. For the couple hundred dollars that a new muffler is, you'll spend less time effort and possible future problems that no one wants to have buying a new one. Plus, just how long does it take to "skin" a muffler and how much is your time worth? Good Luck, TomC

tekebird · July 25, 2007, 08:36:16 AM

why would you cover over rust.

GM Mufflers can be rebuilt if the ends are good...take them apart and put new sides on

Barn Owl · July 25, 2007, 08:41:07 AM

Tom,

If the replacement only a couple of hundred dollars I would go with a replacement. If we are talking a grand, I will re-skin it, re-baffle it, etc. I have done it before with good results and I feel confident I could do a good job. As for the time it takes, it's not about time; it's about fun of fabricating it. I have done enough fabb'in to be somewhat proficient at it. Not everyone has, so as a general rule, your advice is sound.

Laryn

Barn Owl · July 25, 2007, 08:48:14 AM

Tekebird,

It would depend on how deteriorated the skin is. If for the most part if it is good, I personally wouldn't disassemble it completely. Each muffler would have to be evaluated separately, there is no one right way to do it, and it never will be "good-as-new". That's the chance you take.

Laryn

Tom Y · July 25, 2007, 09:21:16 AM

I have a new bus muffler to sell, and if intrested I will put it on this board for 45.00 + shipping. It has 5 inch inlet and a 5 inch outlet, but they are not on the same end. So it may not help you. Tom Y

ol713 · July 25, 2007, 04:48:11 PM

Quote from: Tom Y on July 25, 2007, 09:21:16 AM
I have a new bus muffler to sell, and if intrested I will put it on this board for 45.00 + shipping. It has 5 inch inlet and a 5 inch outlet, but they are not on the same end. So it may not help you. Tom Y

If it is for an MCI, I would be interested. No telling if my muffler has ever been changed. A new muffler would be a good change.
Will look for it on the board. Thanks, Merle.