Muffler Options?

Lostranger · April 25, 2015, 06:09:26 AM

During paint prep, I discovered that my OEM muffler has a gaping hole in the side. I have to do something since the blast is scorching/sooting the new paint on the access panel.

TinyPic insists on rotating this photo 90 degrees left.

I'm not even going to contact Gillig about their price. I suspect the OEM is overly restrictive, anyway. LuckyChow suggests what I think would be a workable patch, but a little research leads me to believe that a Donaldson muffler might be a reasonably priced option. Some volume increase would not be a problem, but DW often sleeps in while I'm driving. Rear bulkhead is well insulated, but that pipe is in her vicinity.

40 Series Detroit. I measure the muffler inlet at 4-1/2". I have about 48" of space before the current pipe goes through the roof panel, but nothing's stopping me from opening the hole if need be for a longer muffler.

Any thoughts?

TIA

luvrbus · April 25, 2015, 06:28:39 AM

United Mufflers or any school bus parts I think that is a Walker or Nelson muffler

Jim Eh. · April 25, 2015, 02:27:10 PM

Check that inlet tube size again. 4.5" is found most often on Caterpillar off road equipment. Not too many listings for on highway use with 4.5". Don't forget the inlet is (usually) I.D.
Here is a link to the Nelson catalogue pages. http://www.nelsonglobalproducts.com/catalogs/

Lostranger · April 25, 2015, 03:39:53 PM

Thanks for the link, Jim. The inlet is 4-1/2".

Lostranger · April 26, 2015, 11:10:26 AM

Just bought a Donaldson truck muffler on ebay. 5" inlet and outlet. The inlet on my muffler measures 4-1/2", but I can't find anything that size in truck muffler catalogs. I will adapt to fit the new muffler. No big deal. The hardest part will be removing the old muffler.

My Gillig parts manual says that the OEM is a catalytic muffler. The new one will not be, but I can't imagine that being a problem. I would expect slightly better flow with the new, straight through muffler.

Jim

Jim Eh. · April 26, 2015, 02:44:53 PM

Really? 4.5" imlet muffler would probably be more expensive than the run of the mill 5" inlet. Quite a number of customers pitched their catalytic mufflers when their truck was brand new. The local Ford dealer (when Ford was selling heavy trucks) would send us catalytic mufflers for us to open them up and cut out the element. Apparently on Ford of Canada's instructions but that would be a closely guarded secret .... ooops.
BTW the Nelson number for your needed adapter is 900096A (5" OD - 4.5" ID). Between 20 - 30 $

Lostranger · April 26, 2015, 02:48:41 PM

Thanks again, Jim. I really appreciate your help.

Jim

luvrbus · April 26, 2015, 04:39:53 PM

If the engine has the waste gate turbo as most of the 466 engines have it will need the back pressure for the waste gate to work,but you can use what ever muffler you choose

Lostranger · April 26, 2015, 05:13:46 PM

Thanks, Clifford. I'll put up some photos as I change it.

Jim

TomC · April 27, 2015, 08:41:14 PM

Go on Donaldson muffler site. They have numerous mufflers from 2.5" up to 6". Should be less than $200. Good Luck, TomC

Oonrahnjay · April 28, 2015, 04:13:02 AM

Quote from: Lostranger on April 26, 2015, 11:10:26 AM... My Gillig parts manual says that the OEM is a catalytic muffler. The new one will not be, but I can't imagine that being a problem. I would expect slightly better flow with the new, straight through muffler.

Jim

The 8.3 Cummins in my '03 Gillig (the donor bus) had a big catalytic muffler, too. I've run it in the shop a few times and even if it's run for 10 minutes or so, you can't see a wisp of smoke or soot and there's no smell of exhaust. I was pretty impressed. However, I'm pretty sure that there's no room in my new installation for a muffler that big so I'll probably need to change out for a "normal" muffler, too.

Thanks for letting us know your experiences, it's helpful.

luvrbus · April 28, 2015, 06:47:37 AM

What are you guys going to do about the code when the ECM finds out the catalytic converter is missing and not functioning,dealers won't help you BTDT

RoyJ · April 28, 2015, 03:29:54 PM

Quote from: luvrbus on April 28, 2015, 06:47:37 AM
What are you guys going to do about the code when the ECM finds out the catalytic converter is missing and not functioning,dealers won't help you BTDT

Does the ISC have a post-cat O2 sensor? I'm pretty sure the early ISBs did not, in which case the ECM does not monitor catalytic efficiency.

Lostranger · April 28, 2015, 04:42:44 PM

Clifford, how do you manage to always look on the bright side?

Inquiring minds and all.

Jim

luvrbus · April 28, 2015, 05:12:18 PM

LOL I just try too keep you guys out of trouble which is hard to do sometimes but I would call DD and let them run the serial number to see if the ECM is reading the catalytic converter on your series 40 or use a Pro/Link and check it yourself if you have one