M936 Exhaust Clamp?

[Mullaney]

It seems that I have a pretty good exhaust leak around the bottom of the muffler. Looks like stainless steel maybe makes that connection? Is there a flange that has just rusted away - or has vibration killed it?

I have a picture...

Doesn't look like there is a clamp on / for the bottom?

 

[cbrTodd]

That bottom clamp is a v-band style clamp, but the flared end of your bellows has ripped off so it's no longer connecting. You might be able to get away with welding a new flange on the bellows, but more than likely the bellows (and maybe the muffler) will need to be replaced.

 

[Mullaney]

Guess I knew that because the more I looked at it, the worse it looked. After I turned it off, I used a business card and it freely passes through the gap. The more I "poked and prodded" the more it the worse it seems. Bummer but thanks for the info. Guess I will start looking for a fix for that in the near future.

 

[Mullaney]

I found a couple of parts at OshKosh. Both claim to fit M936. It may just be how I am looking at it (without taking off the guard) but my muffler seems to have the inlet in the center...

I have not cut off the clamp yet to SEE which part is really the problem. Pictures below from https://www.oshkoshequipment.com/products/detail/45/25/Muffler-Exhaust-Silencer

 

[simp5782]

I found a couple of parts at OshKosh. Both claim to fit M936. It may just be how I am looking at it (without taking off the guard) but my muffler seems to have the inlet in the center...

I have not cut off the clamp yet to SEE which part is really the problem. Pictures below from https://www.oshkoshequipment.com/products/detail/45/25/Muffler-Exhaust-Silencer

Cut the pipe above the top clamp on the muffler. Cut the pipe under the bellow and Remove the bellow. Buy some 4inch flex pipe and clamp it in place

I've got an under cab pipe if you need it

 

[Mullaney]

Thanks simp5782 .

I will get my cutting tools and supplies gathered up. Looks like a good Saturday morning project. I will report back if I need the under cab pipe.

 

[M35A2-AZ]

Be sure to order new gasket when you go to put it back together. The pipe in the post will fit all the M939 trucks.

 

[Jbulach]

Before you buy a muffler put an add in the parts wanted section. IIRC there are several guy’s here with NOS for around $100.

 

[Mullaney]

Thank You!! I will report back what I find and will definitely give the "Parts Wanted" section a try.

 

[Mullaney]

I got a super deal on a muffler from Floridianson! It isn't on the truck yet, but it made it out the door and into the truck...

 

[Steelreaper80]

Has anyone ever done a dual exhaust set up? Is there any benefit?

 

[simp5782]

Has anyone ever done a dual exhaust set up? Is there any benefit?

I've seen dual 6 or 8in stacks

No there is no benefit with these trucks. 4in is plenty for these trucks

 

[Steelreaper80]

I've seen dual 6 or 8in stacks

No there is no benefit with these trucks. 4in is plenty for these trucks

Doing a complete muffler replacement this week. Top of the muffler rusted out and the stack wobbled off. Still have the stack, just need to replace the muffler. Just got in all the replacement hardware. No stack=sucking in diesel exhaust into the cab. Not fun for a passenger!

 

[charlesmann]

Iv gotta “fix” my muffler too. Its completely rusted out at the bottom. So instead of putting a new muffler on, im just going to straight pipe it so i can get it to pass inspection and hope the dot inspector waives some things bc it’ll be registered as a farm truck. Im restricted having farm tags, but a lot less restrictions than having former military tags, and a whole lot cheaper than regular registration. I looked it up and for a 1 yr normal, non dot truck, at my weight rating, is $360, compared to like $15 for farm tags per yr.

 

[Steelreaper80]

I finally fixed mine. I had no idea how bad the muffler was. Rotten all over. So much quieter now and have the stack on. Putting a pop cap on it to keep the water to a minimum to prevent a repeat.

 

[Mullaney]

I finally fixed mine. I had no idea how bad the muffler was. Rotten all over. So much quieter now and have the stack on. Putting a pop cap on it to keep the water to a minimum to prevent a repeat.

Wonder what ever happened to the exhaust "flapper" (picture below) rather than a bent pipe? I know they rattle and clank sitting at idle - but it isn't like these trucks are going to sneak up on anything... OR is the bend in the pipe to push the exhaust out away from the truck maybe? OR is that eventually they stop flapping and get stuck open?

 

[Mullaney]

Wonder what ever happened to the exhaust "flapper" (picture below) rather than a bent pipe? I know they rattle and clank sitting at idle - but it isn't like these trucks are going to sneak up on anything... OR is the bend in the pipe to push the exhaust out away from the truck maybe? OR is that eventually they stop flapping and get stuck open?

View attachment 813282

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So, most folks don't reply to their own post - but this thread went dark in September of last year. Might have been because the guy who was asking questions was me. So, I have the answers to how I managed to get my muffler installed. Read on...

The top pipe was pretty well "shot". The connector to the muffler was just about rusted away too.
I did my homework. Hunted up the part number in the TM and started shopping.
Several companies offered NOS replacement exhaust stacks for around $200 and shipping.

Really, I am not a cheapskate but that just seemed a little much to me. I went to NAPA. Got myself two clamps (figured the other end would be the same) like the image below ($28 each, American Made). Little bit of cutting with a cut-off wheel and an impact gun attached the new 4 inch exhaust stack with a turnout to the new muffler.



Same at the bottom. Rust on the connector on the UnderCab tube, but the pipe itself was perfectly fine. I hate to say I didn't bother to look to see what a new one would have cost. (picture above) Little bit of paint and it was good enough to make me happy. My truck is already too far from standard military specs to ever be judged in a show, so I decided to use my money elsewhere.

ANYHOW, the problem is solved. New muffler installed. Nice and quiet - or as quiet as it gets.

 

[charlesmann]

I ended up cutting the flange off my muffler and used a tig rod as filler, used my oxy/acet rig and brazed the flange on the straight pipe. Not using flux made for an ugly weld, but doesnt leak. I do NEED to find a flapper for my pipe. Iv been using a bucket when im gone but here lately, while at hm, iv been forgetting to put the bucket on and we have had several good down pours. Im gonna look for a flapper, but i think ill just cut a hole and weld a 1/2 npt nipple on and put a brass plug in to i can drain if need be, even after putting a flapper on