Does the exhaust really need to dump outside the body of the bed?

[NerdNoise]

So I need to put a new muffler in as the current pipes are in pretty bad shape. I there any compelling reason that I can't just take a new universal muffler weld on a bone yard flange and bolt the muffler right onto the catalytic converter and just dump down right out of the muffler and ignore making a new pipe to the back of the bed? I know that there are laws that state you need to dump past the body of the vehicle, but is there a common sense reason? Temperatures? Is that it?

 

[raevenzero]

I've been running mine dumping under the bed until recently. I also didn't have a CAT. I found that when sitting still, I would get a lot of fumes. My eyes would burn and my wife always said I stunk after driving the truck. It was a 4runner, so I also would get a lot of fumes anytime I cracked the back window. It would just suck them in. Besides that, I would get a lot of drone from the exhaust, which got annoying on long trips.

I just build a full exhaust after a couple of years running with it cut short. Much better, and since it's winter, you can see the exhaust shooting out away from the body. Before, you would just see it rolling from underneath and up the sides. I have to admit, I do think it sounded better (from the outside) cut off than it does now with the full length 2 1/4".

 

[Devilmans Hand]

You should never have the tailpipe dump under the body. Some locations are also better than others to avoid breathing in exhaust fumes if your windows are open. Exhaust pipes are cheap and CO can kill you.
Also consider that water vapor is in your exhaust fumes and will promote corrosion in the area where the exhaust is directed.

 

[raevenzero]

My exhaust once melted my spare

It cost me $28 to finish it and run it out the back. Wish I would have done it sooner. A month later, I'm going to swap engines and have to run it on the other side D'OH.

 

[Combat Chuck]

Dumping your exhaust out under the bed is a recipe for rust.
Cars exude lots of moisture, especially after a cold start. This happening again, and again over a few years, and you suddenly have a swiss cheese bed!

 

[toy4xfun]

not to mention that the Cat converts other emissions and turns them in to sulfuric acid gas!

 

[raevenzero]

I never had a corrosion issues, just CO2, which is bad enough

 

[flash02]

My exhaust once melted my spare

It cost me $28 to finish it and run it out the back. Wish I would have done it sooner. A month later, I'm going to swap engines and have to run it on the other side D'OH.

Haha mine too

Sent from my iPhone using IH8MUD

 

[Combat Chuck]

I never had a corrosion issues, just CO2, which is bad enough

I've seen it on old 40s and 55s that had had their engines swapped, or their exhaust systems butchered.
Serious frame rot on one 40.

 

[Devilmans Hand]

I think the 60s suffer from frame rot right next to where the exhaust dumps out too.

 

[DanS HJ-45]

My truck long ago had the exhaust rust and the last foot of the tailpipe simply fell off. I drove it like that for another month or two. To this day, that is the ONLY rust on my truck--where the exhaust was.

I have also cut the exhaust on a 60 just to install new springs, and drove it into town to get a new tip on the exhaust to get it out from under the truck. It melted brand new OME bushings in less than 30 miles of downhill driving.

Don't exit it under the body, unless you like rust, or other stuff.

Dan

 

[H8PVMNT]

I ran mine to just above the rear end with a little down turn on it. It wasn't really a problem on the pickup for fumes but I sure got alot more axhaust noise in the cab than when it gets to exit the body.