Add flex pipe to exhaust

[T101]

Also posting in the Doug Thorley headers thread as it relates to that product.


OK, I just got my truck back from having the DT headers installed. The installation went smooth but the repeated connecting and disconnecting of exhaust parts made my 14 year old exhaust gaskets basically disintegrated, and now instead of hearing the annoying ticking from the manifold, I'm hearing it at the flanges. A few of the flanges connecting the various exhaust sections were also rusted pretty bad, so I'm not sure that new gaskets alone will solve the problem. I kept the stock upper/upstream cats. I ordered all new exhaust, everything after the first set of cats, and have not yet installed.

MY QUESTION: My mechanic welded the cats pretty good, but any welding like that can never be quite the exact dimensions as original. While investigating the leaks at the flanges, I can see that when UNBOLTED, the flanges don't perfectly line up like stock, and are slightly askew, maybe a 1/2"-3/4", but I still have to muscle to two sections of pipe together to get the bolt holes to line up.
especially here, where this crudely drawn arrow is


With the bolts in, the two sections will seal together good enough, but I can tell that there is some tension when bolted. I'm worried that since our exhaust system is so solid with no 'give' anywhere, that the tension would or could be transferred to the manifold and cause new leaks in a hard to reach spot, or that the tension may prevent tight seals when I put the new exhaust in.

Curious if anyone has ever replaced a small section of exhaust pipe with a section of flex pipe? I'm surprised our trucks don't have any flex sections. Do you think it would be beneficial, especially in an offroad truck? Or do you think that new exhaust and new gaskets should cover everything? If I do add in a couple flex sections I'd like to do it while I have the parts off the car instead of dropping the truck at an exhaust shop again.

THANKS!
-Greg

 

[gaber6]

I imagine our rigid system is ok. There is plenty of rubber hangers giving some movement as needed. Just replace the factory donut things and if it's not enough, pack it with some muffler sealant before closing it up.

 

[Billynath1988]

I had this ticking.. it was painfully annoying..

Its the spring bolt joint that connects to the muffler pipe.. those springs corrode and make a ticking jingling noise as they flex.. Its hard to recreate when the truck is parked and off, and only when you drive down the road.

Replace that gasket and those bolts/springs and it will be nice and quiet again

 

[blackoutt]

I replaced all these gaskets, spring bolts, etc. just recently after having leaking sounds for a couple years after doing my headers. I used remflex gaskets for the header to downpipe since I have custom 2.5" flanges and they are great gaskets. All those leaks cleaned up and my exhaust still sounds airy. I'm chalking it up to thin walled headers with no cats and loud valvetrain noise. I'm living with it for now, as is 0verland in his thread about DT headers and leaky sounds. I went so far as to pressurize and leak check my exhaust piping with soapy water. All sealed.

 

[T101]

My leaks are loud for now, the last of the new exhaust parts come Thursday and I’ll spend Friday morning installing. Should be quick because I’ll likely just cut everything instead of unbolting since everything is being replaced. Confirmed all leaks by putting a shop vac in blower mode and shoved into tailpipe. Air was blowing out of every connection. Hoping the new parts and gaskets solves everything. For a minute I was ready to say F-it and go buy something new

 

[UrbanRunner651]

so you are getting an aftermarket crossover?
should just look into eliminating the flanges if they are rusted and the front end is already custom.
I wouldn't use flexpipe. It is cheap and will rust through within a year.