Ok, what's the idea here? I saw this on a truck at the Mexican place I eat at every day.

Why the vent thingies in the pipe after the muffler? I have two ideas:

1) Draw air into the exhaust stream to make the smoke less thick.
2) Draw air into the exhaust stream for noise reduction / tuning.

 

Spark arrester. For those really BIG backfires!

 

Some of the heavy duty Ford PowerStroke PUs have a similar style tail pipe.

 

Ok, but why?

 

When I saw the first one at a dealer, I asked a "salesman" about it. He said now with "cats" on certain diesels, the exhaust is extremely hot and can cause injury or fire. That style tip allows air to be drawn and mixed to help cool down the air. I have never really read up on it to know if it is accurate.

James

 

If I had a third theory in my opening post, it would have been temperature... but I never thought of that.

It makes the most sense.

 

Sorry guys....new EPA regulations....it's part of the new system that Re-Burns the exhaust gases, and use UREA mixture that is injected into the motors....James, if your buses don't have those engines yet, they soon will be, although International Harvestor has a different approach, more like the old system....but, that is what it is all about....I'm still running the pre-emmisions motor in mine....thank god, and that is also why CAT quit making truck engines. They refused to use this set up in their motors...it isn't required in bulldozers, excavators, and farm tractors.......yet....lol

 

From my research that is an exhaust gas cooler as mentioned above. These are required as the cats can increase gas temperature to 600 degrees F.
The urea injection would not be visible at the exhaust tail pipe. Urea injected systems could use this tip, but so could a non urea injected system.
YouTube - ‪The science behind Mercedes-Benz BlueTEC‬‏

 

it slobbers some ugly looking liquid around the exhaust, stains the chrome...it's a joke Dave...although on an exhaust like on the pickup, it wouldn't be as noticeable as on the stacks on the tractors...

 

Our last fleet of coaches are several years old now. At that time they had re-gen cats and egr valves. I am not there anymore so I am not sure what they will get next. Hybrids are showing up now, still diesel thou.

James

 

no more buses....bet that breaks your heart...lol....My cummins loves egr valves...I haven't studied the new gen motors yet, but I am not liking what I am hearing...and all that slobbers running down the sides of those beautiful chrome stacks can't be good either...rusty colored water vapor my butt...international harvestor dropped cummins engine from their line because they couldn't agree on the motor, so IH is making their own motors now, and cummins is making a deal with Pete/KW...and CAT is out altogether...so much for good running truck engines...Not sure what Detroit is doing...since they are all foreign owned now..

 

That's the newer model of the Flux Capacitor!