exhaust wrap question

ok so i have some terrible resonance vibrations at times from my heatshielding around my gas tank on the 6. nothing seems to stop it. even when the pipe was hanging down 2 inches away from it it would still vibrate. ive tried epdm washers on it and still made the same horrible bzzzzzzz rattattat sound its sporadic but does does it sitting at idle after a run through the gears for a good 20 seconds and sometimes when taking off. best i can tell nothing touches them and its just vibration that happens sometimes (this has been on going for years) could i removed the shields and just wrap the pipe? pipe is 3 inch aluminized 14 gauge. gets a lil to warm to touch after about 20 minutes of idle before that in this section its able to touched just not comfortably. what says yall?

I would ceramic coat the pipe before wrapping it.

coating is out of the question. system can not come out of the car and i refused to cut up a perfectly good exhaust system to coat something. especially since i no longer have a welder nor direct access to one.

If the buzzing heat shield is on the gas tank what good would wrapping the exhaust do? The heat shield is buzzing from vibration, not heat. 1st guess is either a shield mount or exhaust mount is damaged or missing. Check all mounts. If you have urethane mounts on that aftermarket exhaust I would recommend changing them as a 2nd guess.

reg rubber mounts. and the shield mounts are all intact nylon nuts and studs. wrapping the exhaust is to remove the shield.

Maybe there's needs to be another hanger somewhere, in addition to what's stock, to stop the vibration. Just a guess.

the vibration will happen just revving at a stop. not from motion. and rubber hangers on the exhaust as is is 8 of them 3 more than oem as is. it is purely a harmonics vibration. not from contact ever.

Add lead weights to said shield and change the resonance?

KATYB wrote: the vibration will happen just revving at a stop. not from motion. and rubber hangers on the exhaust as is is 8 of them 3 more than oem as is. it is purely a harmonics vibration. not from contact ever.

So this qualifies as a science project. Did the new exhaust add or delete a flex joint somewhere?

I had a similar issue when I "fixed" a sagging rubber mount by adding a hose clamp. The whole exhaust vibrated enough to feel it in car at a specific RPM, nothing above & nothing below - just a great shake within ~200 RPM range. I hit the natural frequency of that part. Swapping in a new mount cured it.

I bet with a little time up on the lift you can pinpoint the source. You may find that only one or two of those 8 mounts are actually loaded. Good luck - you'll get there with a little head scratching...

as a warning, I wrapped the headers I installed in an econobox, and now, about 5 years later, the "coated" (ebay special, so Im doubtful it was anything other than bbq grill paint) downpipe rusted clear thru. That wrap retains water like theres no tomorrow. If youre gonna do it, Id suggest some DEI Silicone spray to seal it before you wrap it.

Yep exhaust wrap has the potential to greatly accelerate rust. Headers should be painted before the wrap goes on, and then the once wrapped it should be painted again or coated with that silicone spray above.

exhaust heat shield rattle? Insert a sheet metal screw into the shield to take up the slack. Done everyday on Subarus

Can you get the car in the air? If so fire it up with someone inside. Blip it, listen for rattles, it may not be what - where you suspect.

The hardest thing to do on a car is diagnosis......

Dan

its thats shield verified on lift. rattles against another shield and the tank. it has done this regardless of exhaust system on her for years. (prob 3 or 4 different systems this one may be ok well is the worst fitting but vibration is the same im never letting someone else build a system again) im going to wrap the pipe and put some epdm washers on everything again and see what happens. and yes im aware wrap will make things rust but im in oklahoma not too worried. i had wrapped from the headers to the muffler on my escort and 85k later and 3 years we had a bad ice storm that killed the wrap but the pipe was still fine. no rust cept at the weld joints and a light light on the seam. still passed the squeeze with pliers test. we dont use salt on roads and only get about 3 inches of snow a year. rain is it. truck we have in the back pasture had the exhaust replaced 9 years ago with off the shelf cheap direct fit stuff from sigma exhaust distrubuting clamped together. and it still has a shin to it if u wipe it with a rag.

when i wrap tho normally i lay a heavy coat of paint wrap while paint still soft then start and run for an hour to cure that paint and make sure wrap has no loose spots then spray everything again in a heavy coat.

Heat shields are overrated. Live dangerously ;) pull that thing out...

KATYB wrote: ...then spray everything again in a heavy coat.

^^key step

pimpm3 wrote: Heat shields are overrated. Live dangerously ;) pull that thing out...

I've done it many times with no negative result. Although I've not done it with a fuel tank heat shield.

In reply to car39: and on mitsus

In reply to pimpm3:

ya lol its the fuel tank that scares me melting and leaking would not be fun.

Change out the rubber hangers to ones that are either harder or softer to change the harmonics.

Jack Enginerd

In reply to Jack:

harder would be the only option softer and exhaust will hit in places during corners.