MC8 Muffler

[tninov8r]

Does anyone know the correct Donaldson, or equivalent, muffler # for a MC8? Any success stories?

[Gary Hatt - Publisher BCM]

For what its worth, my mechanic has removed the stock MC7/8/9 mufflers on 2 buses recently and knocked the guts out of it and then welded them back up and owners have reported they run much cooler.

My Series 60 was overheating and the same mechanic removed it and replaced it with a Resonator and my bus runs much cooler too.

The stock muffler is quieter which is kind of important when you have 40 - 50 passengers on board and driving thru big cities and when the bus is relatively new, but once the radiators start getting restricted, things start heating up and a restrictive muffler works against you in a bus conversion. 

Something to think about before you order a replacement.

Or if you really want a stock muffler, you can run with your back doors open when thru Arizona in the summer like I used to do. 

Gary

[edvanland]

Gary I am so glad Joe cut my muffler off and we put on the resonator. Our MCI 7 with 8V92 runs so much belter. Less smoke under power, doesn't bog down on hills like it used to, runs cooler and just all around better. I wish I would have known and done that 17 years ago. Thanks for introducing me to Joe

[bevans6]

Donaldson style 5 is inlet and outlet on the same end, MCI is an odd size outlet 4.25" I think, I used a M120131 which is 5" in and out, resonator, with a turbo engine, the same size but a muffler is M120176.  It is significantly smaller and lighter than the stock MCI muffler but with a little fab work on the mount it works just fine, sits in the original spot.

[tninov8r]

Have found a local supplier for the M120131 Donaldson MUFFLER for our MC8 - does anyone know if this muffler will work/fit in our MC5A as well? Stock ID was 8b-20-1. Thanks. 

[Gary Hatt - Publisher BCM]

Many people are tearing out their MCI mufflers and installing straight-thru Resonators instead. The stock mufflers hold back too much air causing overheating especially when engines get old. 

Others are splitting them open and cutting out all of the baffles to it can breathe better and welding them back up.

They will be a bit louder without a standard muffler but the resonator is not that loud and lets the engine breath a lot better.

[TomC]

I took off the giant transit bus muffler (was very quiet) and replaced it with the Donaldson 120131 10x15 oval 5" same side in and out. It is a high flow turbo muffler. If you look inside, it is empty except for the baffle that separates the right from the left. It puts out a nice tone-lets everyone know you're there, but not too loud. No need for an additional resonator. Highly recommend this muffler. I'm using the same muffler on my truck conversion. Good Luck, TomC

[chessie4905]

Yeah...it is not very loud from 35 to 40 feet upfront.

[Jim Eh.]

Yeah...it is not very loud from 35 to 40 feet upfront.

[Glennman]

This sounds like a great idea to help with hills and overheating. What is a resonator? is that simply a tail piece add on?

[DoubleEagle]

It's a muffler with a straight-thru design, usually with a perforated center tube with fiberglass stuffed around it, like the old hot rod "glass packs". It reduces the back pressure while making the exhaust sound more robust (or noisy in some ears). 

[buswarrior]

Great...

More old buses driving around making a hell of a racket.

And that won't cause the hobby any trouble with the authorities or public opinion?

Do we really need more attention?

If your bus overheats, fix the cooling system.

Happy coaching!
Buswarrior

[Gary Hatt - Publisher BCM]

Some call it "noise".  I am a Bus Nut, I call it "music".  And to use Jakes on top of that?  WOW! 

When idling thru a campground, a Resonator does not sound that much louder than a regular muffler if you keep off the throttle.

I would much rather listen to a bus than some of those "noisy" Honda cars out there with "stock" mufflers that drive me nuts. 

I used to have a Harley in a previous life.  I guess people would hate me for driving that too.   

[chessie4905]

Some of us hate you for all the noise. 🤨

[DoubleEagle]

If we have resonators we would still be much quieter than a Harley with straight pipes with the radio turned up loud so that everyone can hear it over the pipes.