2500 Suburban 96 6.5TD 205K miles - Run hard and put away wet all the time! Most driving is open highway at 70+mph - well.. back roads for that matter too.... :>)

4" stainless (with muffler) all the way back
opened up breather and PMD cooler... thats it... no chips...


OK.. went to a 4" stainless exhaust and man-- talk about loud...

mostly at high speed and on pulls I need to wear noise canceling headphones

- no kidding.....

205K 4' stainless all the way back

Any suggestions too keep the performance and loose some of the excessive noise... if you want to hear a turbo - I've got one.. sounds like a dump truck.. Any recommendations on a muffler what will quiet things down a bit?

OK - another thing.. replaced the manifold studs with new crossover pipe..

Keeps loosing stud nuts!!!! no kidding... came back from California (Maryland) with a noisier truck... looked around and found I had 1 nut left.

Local repair shop put it on the lift and put on new stud nuts... and then 400 miles later found one laying in the driveway. crawled under then and sure enough.. it belonged to my suburban!

2 different shops put them (back) on - not a home project laying on my back in the driveway...

so-- short of welding the darned things on there, anyone heard of anything like this problem...?


thanks to all and Merry Christmas!\
Wayne

Red Lock Tight should help. On the package they have a diagram of the differant stregnths. I think the green is even stronger than the red. Used it on some bolts on my tow truck that would vibrate loose every two months. Its been two years since I used the lock tight.

Does your truck have a muffler installed, or did it get a delete? A flow through muffler should be sufficiant to cancel the noise. If it is not try a turndown tip. Since the back end of the body is right over the tip, it could cause some resonance inside the cab. A SS turndown can be bought pretty cheap and can even be clamped on instead of welded.

Hope this helps.

I originally had my 3" system straight piped and it was a little loud for my tastes. I diddent want to quiet it, just take the edge off it. A little research turned up the Dynomax Bullet racing 'muffler'. It is a straight through glasspack, but with a Cherrybomb type hole setup as opposed to the Thrush louvers, so there is basically no backpressure created. It took the edge off, while still allowing the truck to sound powerful. The only downside is it did quiet my turbo noise more than I would have liked. You can still hear it (expecially outside with the truck driving by), but before it HOWLED, just like the proverbial dumptruck.

with the Bullet...
http://s11.photobucket.com/albums/a194/cmb3366/?action=view&current=Diesel2.flv


Heres a link to the Bullet, only $37.99 for a 4"in 4" out http://www.jegs.com/webapp/wcs/stores/servlet/category2_10001_10002_19683_-1

Loose Manifold Flange studs... only way to fix 'em is to pull the studs and replace them with new ones. Make sure they tighten the stud properly before tightening the nut. Just putting new nuts on is like taking asprin ... it's not a pain-killer; it's a pain-postponer.

Loud 4" stright-thru ... go to a muffler shop that has just done a new kit on a Duramax. Get the 4" Duramax resonator from the scrap system (it's straight-through, so no extra back pressure) and weld it into your 4".
Purrs like a kitten. OK, a cougar. But it will be about 1/2 as loud as it is now, and the drone will mostly disappear without making the machine sound like a grandma-mobile.

c now i'm thinking i'm pleased when i got my 4" system i got the muffler. it is a 8in diameter x 18 or so inches. but is see thru all the way. guess it's got 2 inch all around for baffle. not much of a muffler at all. butt step on it loaded and i can scare pedestrians. don't ask how i know. hahahaha. lol and the exhaust system is by warpspeed on ebay ......

2500 Suburban 96 6.5TD 205K miles - Run hard and put away wet all the time! Most driving is open highway at 70+mph - well.. back roads for that matter too.... :>)

4" stainless (with muffler) all the way back
opened up breather and PMD cooler... thats it... no chips...


OK.. went to a 4" stainless exhaust and man-- talk about loud...

mostly at high speed and on pulls I need to wear noise canceling headphones

- no kidding.....

205K 4' stainless all the way back

Any suggestions too keep the performance and loose some of the excessive noise... if you want to hear a turbo - I've got one.. sounds like a dump truck.. Any recommendations on a muffler what will quiet things down a bit?

OK - another thing.. replaced the manifold studs with new crossover pipe..

Keeps loosing stud nuts!!!! no kidding... came back from California (Maryland) with a noisier truck... looked around and found I had 1 nut left.

Local repair shop put it on the lift and put on new stud nuts... and then 400 miles later found one laying in the driveway. crawled under then and sure enough.. it belonged to my suburban!

2 different shops put them (back) on - not a home project laying on my back in the driveway...

so-- short of welding the darned things on there, anyone heard of anything like this problem...?


thanks to all and Merry Christmas!\
Wayne


I have the 4" system on my Suburban, (not stainless) with muffler. The muffler is straight through and it is nothing like you are describing.

If it was that bad my Wife would definitely tell me, as it is her daily driver!!

I think all your noise is coming from the manifolds.

I also run 4" all the way back (3" from turbo of course) - nothing like you described. It's beefy, throaty, and free flowing, but not annoying and loud. Has a flow-through muffler. I tried it without the muffler for awhile (just dumped it before where muff would be) and yeah... that was just chest-pounding.

I'm with jifaire on the replacement of the studs. I've dealt with this exact problem time and time again on SBC/BBC engines. You also want to use the high-temp locking nuts (not nylon esna nuts). They have an ever so slight crimp (NAPA sells them), -and they do work perfectly for this application.

Like jifaire said, -proper stud installation is critical. The use of loctite is surely debatable, -as even the high temp stuff is only really good for 380F or so, -and those manifolds and crossover get much much hotter than that.

The crimped locknuts actually fit very snug, -so special care has to be taken when you install them. Don't use air tools, or else they will likely gall on the studs, -then you'll be cussin'.

In fact, some good anti-seize with copper or nickel works great on those locknuts, -then run 'em up by hand slowly to prevent galling the threads.

As for your 4" exhaust being too loud, -that's kind of the nature of the beast (that means it's working). There are some good straight through glasspacks out there that will help a little with the racket, -I have one on my 4" setup. I ran 4" straight (no muffler) for almost 6 months before deciding I couldn't handle it anymore, -and installed a glasspack, -much better.

It did muffle the turbo also, -which I didn't care for, -but the thing is much more driveable now that it barks a few decibels lower.

Welcome to the diesel place! This is undoubtedly THE place for bona-fide 6.5 info, -and the "brotherhood" of fellow 6.5'ers is a pretty tight group (even though sometimes we act like we are in fact siblings!)