Modifying a Muffler

[Provincial]

I have a MDI-Yutani MD400 excavator (100,000 pounds) that has a Mitsubishi 6-cylinder diesel engine. The muffler rotted out and a new one costs $2,700.00 with a 6-month wait, plus shipping from Japan. Looking for another option, I discovered that Walker makes a similar muffler, except it is 4" too long, the inlet and outlet are oriented in a different angle, and the inlet and outlet diameters are 4" instead of 3-1/2". For $148.00, shipped, I decided to do some modifications.

Photo 1 shows the old and new mufflers. The old one is longer than it looks because of the rot.

Photo 2. I laid out the cuts to take a 4" section out of the main shell in the inlet chamber.

Photo 3. The inlet perforated tube is almost perfectly spaced from the end.

Photo 4. There is just a baffle and no perforated tube between the inlet and outlet chambers, but the outlet has a perforated tube.

Photo 5. The cuts I made in the shell left me with enough room to use material from the area that was removed to make an internal reinforcement for my splice. I tack welded it inside the shell.

More in the next post.

 

[Provincial]

Photo 1. The inlet tube is oriented 45 degrees from the outlet. I used levels to double check my calculation of the arc I laid out.

Photo 2. I pressure tested my welds with 3 psi of air pressure and soapy water. I had shortened the inlet and welded a reducer onto it, so I tested that weld, too. I'm not much of a welder, so I had to fix several leaks!

That yellow thing is a 4" plug for testing water pipe in the exhaust tube. The inlet is made of a 3" PVC pipe rubber coupling and a 3" PVC pipe cap with a stub glued in it and drilled and tapped 1/4" NPT for the air fitting. It also serves as a pressure tester for a Ford 7.3L diesel turbo/intercooler system leakage.

After all the welding, I sprayed these areas with VHT high temperature Aluminum paint.

Now to install it in the excavator.

 

[jhn9840]

Looks very well done. For $2500 and 6 months time it’s worth the effort. Show us a picture of it installed on the excavator.

jhn9840
John

 

[matt_i]

Very nice! What did you do to address the 3.5" outlets vs the 4"? Sorry if I missed it...

 

[SteveH-CO]

For being 'not much of a welder' you did a fine job. nice work! Love how you used the 7.3 boost leak tester for this.

 

[rsanter]

Good job, I would have done the same in your place.
That much money and that time delay is insane for such a basic product

 

[Provincial]

Very nice! What did you do to address the 3.5" outlets vs the 4"? Sorry if I missed it...

I welded a reducer into the inlet. You can see it in the photo of the pressure test, with the piece of 3-1/2" tubing clamped to it for the test.

I have another reducer for the exhaust. It clamps to the outside of the 4" pipe and the 3-1/2" pipe is clamped inside of it

 

[zkdiesel]

Nice job. Looks easier/nicer than that last cat 953 hood/intake/stack I made from scratch when rust killed it.

 

[Provincial]

Looks very well done. For $2500 and 6 months time it’s worth the effort. Show us a picture of it installed on the excavator.

jhn9840
John

Here are some photos of the installed muffler.

 

[bonneyman]

Way to go!

 

[kbs2244]

$2,700 and 6 mo wait?

Now I know why I see so many exterior mounted mufflers on construction equipment.

 

[Mgdoug3]

That muffler looks very similar to a muffler off an International 1440, 1460 and 1480 combine.

 

[HoosierBuddy]

Nice job!

 

[OOBER]

Nice work!

Mufflers are one of those mysterious things until you have cut a couple open and realized for the most part they aren't complicated. Good job using your resources to make it work!

Thanks for posting.

 

[OccupantRJ]

Good going! A man of my own nature. I would not have spent the cash either. That is insane for essentially a tin can. One could be hired to be scratch fabricated for less than their price.

 

[bwringer]

So how's it sound?

 

[Strouty]

I had a similar situation, but I just patched the snot out of the original, I may steal your idea for the next time it has an issue. Mine was a 4cyl mitsu, but similar price for replacement.

 

[Provincial]

So how's it sound?

Pretty good. I had it straight piped for a while, and it was LOUD!!!! It is probably 10% louder than the original muffler now. That is because the Walker has perforated tubes in and out, with just a flanged hole in the center bulkhead. The original muffler had perforated tubes in and out, plus two bulkheads that make a center chamber. There were perforated tubes in and out of that center chamber. So the original muffler should have twice the attenuation, but it doesn't seem that way in practice.

Thanks for the compliments, everyone!

 

[pgk]

Wow a 6 month wait and $2700.00 for a muffler! Geeze! Awesome way to save a few bucks man! Just don't forget to use your ear protection..

Pete

 

[lakeroadster]

Nicely done sir. How can any company justify $2,700 for a muffler? That's just insane.

 

[whateg01]

Nicely done sir. How can any company justify $2,700 for a muffler? That's just insane.

Because it isn't the average Joe who buys an excavator. Construction companies aren't necessarily full of fabricators, so they spec a "special" muffler or other part and the company needs the equipment running so they pay the money. Then, when the equipment gets old, guys like us end up with it and won't pay what they want.

Dave