Louie

I just reinstalled my ATs and I can't get rid of a gas leak on the driver's side muffler, where it connects to the mid-pipe.
I tried a few times already to re-arrange the muffler and the clamp, but there's still a small leak from the guidance notch. I'm thinking about using some high-temperature teflon tape or red silicone, but the passenger's side muffler is gastight just by using the provided clamp.
How did you guys install your aftermarket mufflers? Were the clamps enough, or did you use some kind of sealant between the pipes?

DoctorQ

If this is a reinstall, are you reusing the Flowmaster AT clamps? These aren't the best clamps and many (including me) have had issues getting them tight enough. Hopefully your exhaust leak is not due to a crimped pipe (either over-axle or AT inlet) from your previous install. Visually inspect the AT clamps for any stress/wear (on threads or nut). If they look OK, I'd suggest you apply some anti-seize lubricant to the threads only. I've heard that failure to apply lubricant can cause the nuts to seize on clamps and potentially damage threads (per a Z06 exhaust website). They also recommend to thoroughly clean hands after use.. and anti-seize lubricant will tarnish SS parts. Here's another important point I pulled off the site: "...clamps should be tightened using a properly calibrated Torque Wrench. Using an air impact gun will damage the clamp and reduce its ability to effectively seal the joint". Hope this helps.

dustindu4

do yourself a favor and throw those flowmaster clamps in the garbage and get some U clamps at the parts store

07GT_BLACK

+1...get some U clamps.

cmplxlgc

I ordered lapband clamps w/ my ATs. Stainless steel and they seal 360 degrees w/ two bolts. got them at Jegs.com

302svt

I am having the same problem. Did you get yours fixed and how. Thanks

Cowtown

If you're trying to get it to work with the stock clamps, make sure to straddle the notch with both sides of the flowmaster clamp, one side of the clamp will be just on the very edge of the flowmaster pipe. This tends to fix up that issue pretty quick.

302svt

That's the way I have them but they both leak at the alignment stud.

Cowtown

Sounds like you need some new clamps then. My friend just installed a set and the left one we thought we had good and tight. One trip and it came apparent it wasn't. I checked it when he was in the car the next day and sure enough there was a lot of play at the joint. He got under there last night and cranked it down and it cleared up.

I'm surprised it's leaking at the stud though, there is a lot of pipe overlap there, but hey if it's leaking it's leaking.

302svt

I am going to try to torque them down better before I buy any more clamps.

dustindu4

ok if you don't want to listen we're done helping

302svt

Why don't you look at my previous post a little better, it says I don't want to buy "any more" clamps, I got the U-Bolts like everyone suggested but I thought I would try to torque them first just in case I didn't have them tight enough like a few other members said. Because once I put the U-bolts on I know it will be hard the get the mufflers back off.

tdbrown75

How exactly can you tell they are leaking? I often wonder if mine are really sealed.

302svt

I got under the car while it was started and wrapped my hand around the pipes were they connect to the mid pipe. I could feel it coming out pretty bad.

SteelTownStang

I had similar problem on my first set. I couldn't get the the supplied clamps tight enough so I went with the U-Bolt designed that fixed the problem. I then purchased a set of Stingers. The Ford clamps basically did the same... could not establish a seal. I ended up using the flowmaster clamps and they worked. Sold the Stinger(DRONE!!!) and went back to the Flows. This time I moved the supplied clamps all the way at the end with the metal rings on each side of the nubs as described on other threads and they worked fine. The trick is to tighten them down hard... almost to the point of snapping.

The leaks are easy to see/find. Start the car up early in the morning when it's cooler, let idle for a few minutes, then crawl under the car and look at the connection. You'll see steam coming from the connection and condensation building up in the area as well. You can ever "cuff" you're hand around the exhaust opening to exaggerate the condition, or have someone rev the engine while you're under there... which can be sacary as you can picture the rear tire going over your head like Phil from the Sopranos... crunch!