Upgraded to 4" exhaust and NOT happy. HELP!

nicksandvig · 08-01-2014, 11:16 PM

Hey guys. I recently had a very reputable exhaust shop here in Oceanside CA do a 4" stainless turbo back exhaust. I have a 98 Club Wagon HD with a 7.3 PSD in it. The guy really helped me out by welding flanges into the new exhaust and mirrored that flange onto my old cat converter. This way when I need to pass Smog here in CA I can unbolt the section of straight exhaust pipe and my cat for inspection. Then back to cat free after I pass! Pretty psyched about that. I am really happy with the quality of his work.

The thing I am not happy about is how freaking loud it is in the van. It's not a drone sound, it's like all the exhaust sound is coming right into the cabin of the van. I know tons of you have bumped up to 4" and wondered if this is just a downfall I wasn't expecting and have to live with. Or if there were solutions, I hope there is!!!! I primarily do long road trips with the van and do not want to hear that much constant noise cruising through Utah in the middle of the night.

Tonight I tried doing sound deadened in the cab. Cut out a little (emphasis on little) engine noise but NO extra exhaust noise. Any insight is appreciated.

Thanks gentleman.

Nick

**Gooseberry** · 08-02-2014, 08:07 AM

You might need to look at the insulation in the dog house and do a thermal wrap on the down pipe.

Make sure none of the flanges are leaking and that the exhaust tip is angled to the back. I noticed a big difference in mine just by angling it more out the back and I do have the wrap on the down pipe with the 4 inch and its pretty quiet.

**BroncoHauler** · 08-02-2014, 08:22 AM

You might want to read this thread and see if it might help with some ideas.

viewtopic.php?f=39&t=8695&hilit=resonator

Herb

JoeH · 08-02-2014, 09:14 AM

I know you mentioned it's not a drone but you could install a resonator in place of your "test pipe" in front of what is your high flow muffler. http://www.ftediesel.com/store/pc/viewP ... category=7

Ford_6L_E350 · 08-02-2014, 09:16 AM

It may be the cat was acting as a muffler and actually reducing the sound level. have you tried it with the cat in place?

Mike

vwteleman · 08-02-2014, 10:35 AM

This may be a silly suggestion, but check that your doghouse is properly sealed to the floor.

Brent

**Gooseberry** · 08-02-2014, 12:17 PM

very good idea

Quote:

Originally Posted by vwteleman

This may be a silly suggestion, but check that your doghouse is properly sealed to the floor.

Brent

Ford_6L_E350 · 08-02-2014, 12:29 PM

When my doghouse wasn't properly seated I had way much mechanical engine noise, but no exhaust noise.

Mike

nicksandvig · 08-02-2014, 01:06 PM

Thanks for everyone chiming in!!

The seal of the dog house was my first thing. I'm good there.

This morning I went in and talked to Jim about my issues. He put the van on the lift and walked me through the entire system. His guys used all the factory mounts and maintained the rubber isolators. Anywhere they added supports they used 3/4"x1" rubber strips as hangers so I'm confident its not vibrating through the vehicle. He suggested adding another muffler. I asked him about a resonator which he said is the same thing, just a fancier name.

The current exhaust system is complete stainless construction and uses a Dynomax Ultra Flo 4" straight thru muffler.

What he believes the sound is, is the material and shape of the van amplifying the noise. Not exhaust drone, but drone through the body. My van is not a SportsMobile (am I still allowed here) and I just have an elevated bed built in the back so I can throw my gear underneath. So I don't have a lot going on in the interior to muffle road noise. However mine is a Chateau model so its got full trim, carpet, 4 bucket seats, etc.

I am wondering if adding sound deadening plate will help. Also considering one of those sound mats. The nice Mass Loaded Vinyl Barriers (MLV) stuff.

Also really considering adding the FTE Diesel resonator suggested in the thread link and by JoeH. Thanks guys.

What do you all think. Start with the FTE resonator, then go from there with sound deadening? Or add a muffler like Jim (at Warners Muffler) says and go from there. Is the MLV stuff going to help?

I'm really worried about this because my van was my baby, and now I can't even hear myself think in there let alone talk to anyone.

nicksandvig · 08-02-2014, 01:07 PM