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Mdt Exhaust


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What are you guys running? Location wise. I have a 4700 with stock weedburner. Doing some internal debating on what to do with it. I want to run a stack, simular to a hdt, but it won't be tall enough to clear the roof of the rv. There is a pretty big gap between the truck and rv though. I just don't want heat or soot damage to the trailer. Any ideas if there is a safe distance to avoid potential damage? Or am I just better of leaving it low and turning it out from under the truck?

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I have an '07 4400 and I have the exhaust running out from under, on the passenger side...4 inch exhaust with a 5 inch chrome tip peeking out just behind the back doors. I have also thought about stacks, but, like you I would be worried about soot buildup on the front of the trailer.

Jeff and Cindy Harvey

2007 Intl 4400 DT570

2010 Carriage Carri-Lite 36MAX1

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Most of us with HDT's remove the stacks and go to weed burners. Is your desire for a stack just looks or do you have another reason? I personally would leave it a weed burner. If you are worried about heat under the bed, I would direct the exhaust out the side. This is how my weed burner exhaust is set up.

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Our HDT has dual stacks and we carry a car between these. The exhaust stacks are turned out and back and exit near the front of the car. We have a small amount of soot on the front of the car after 500 miles or so but it washes off easily. The exhaust is within inches of the car. We haven't seen an increase in temperature on the car. The air movement at that height seems to take care of that. The front of semi trailers that are close to the exhaust are an example of what can happen up close but there is a lot of air movement at that height and just a small space will negate most of the problem if the engine is in good condition. We haven't seen any soot on the 5er. I believe the stacks are a little less noisy in tight places.


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Yeah, I'm just interested in the the appearance aspect more so than anything else. That and if I let truck idle while parked the smell is, well smelly. Figured if I put a stack it would lessen the diesel exhaust smell. Depending on the breeze it'll also come in the rv. I also don't like the soot build up under the truck. So it's either run it up out of a stack or elbow it out the side.

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I don't care for the under truck exhaust location, my preference on an MDT is out the passenger side just ahead of the rear wheel. That puts the soot buildup as far from the rest of the truck and the fiver as possible.


My Stalick built 4700 had pretty dual exhausts that ran down the bed from the back of the cab to just ahead of the wheels, they left a lot more soot on the truck and fiver than a similar truck that had a single pipe and pointed to the side rather than the Stalick curved end. The higher flow from the single pipe and the better angle away from the rig both seemed to help keep soot down.


With the low height of an MDT you either have stacks sticking way up in the air or you are going to have the exhaust flowing down the side, and depending on turbulence across the front of the fiver, leaving a lot of soot. Also if the fiver isn't pretty air tight you are likely to get some of the diesel stink and soot sucked inside. They might look pretty but I don't think they are a good option for using the truck.

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My son hauled a 53' reefer last week with his Freightliner and after 500 miles the plastic cover over the reefer unit had started to melt from the exhaust. I realize most fifth wheel campers have more space between the stack and the nose, but that exhaust gas is hot.


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With our 2005 it had a stack and especially after it rained we would have soot all over the back of the truck and front of the trailer. We now have ours exit the side down low in front of the rear tire.

If you want it for looks, just mount the stacks but don't hook them up!



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I'll probably run it out of the pass side in front of tires. It's the smart way to go, and cheaper. I still do like the thought of a single stack, but again it's just for appearances. For once in my life maybe I'll choose function over form..lol..

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  • 1 month later...

Ok. I decided to go under the truck and out the passenger side in front of rear wheel. I did do a 4 inch straight pipe and I don't think I could be happier with it. It sounds good, and can i hardly tell a difference on the noise in the cab.

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