• If you currently own, previously owned or want to own an Avalanche, we welcome you to become a member today. Membership is FREE, register now!

Possibly stupid question but hey you live and learn

Jwh91

Full Member
Joined
Mar 30, 2018
Messages
40
My cats are clogged, I'm more that certain, truck came from snowy weather, I'm throwing downstream O2 sensors and I'm averaging 14.9 mpg while driving like I just got out of the Alzheimer's unit. Here's my question, do I absolutely HAVE to weld the free flow cats onto where I cut the old ones off? I mean it's past the main o2 for fuel so it shouldn't affect air/fuel mix. Can I just use exhaust sealer and JB weld with a rubber boot clamp on each end of the pipe?
 
YEs to be street legal you must have a cat.
 
ygmn said:
YEs to be street legal you must have a cat.

You misread my post, I asked is welding is the only way to connect the cats I bought without losing vacuum or leaking oxygen into the exhaust
 
Cats get REAL hot... and I am afraid JB weld and rubber boot would melt away.

Get them welded on if they were intended to be welded.
Local shop should not charge too much for this. My guess $50 or so.
 
JB Weld has a limit of 600 degrees Cats get hotter than that.
 
MS03 2500 said:
JB Weld has a limit of 600 degrees Cats get hotter than that.
Agreed, even "High Heat" epoxies are only good for up to 900 degrees, for the cost of getting them professionally installed, I wouldn't risk it.
Exhaust leak under/in front of the cabin  if it fails is not something i would take the chance on, not to mention the possibility of fire, just my $0.02
 
So what about standard piping and band clamps? Will that be okay? Just found out I have a hole in my mid pipe past the Y
 
You can get just a replacement y-pipe with the cats already welded in that you can then just bolt in.  GM doesn't require their dealer service shops to do welding so their solution was a bolt-in.
 
enoniam said:
You can get just a replacement y-pipe with the cats already welded in that you can then just bolt in.  GM doesn't require their dealer service shops to do welding so their solution was a bolt-in.

I might need to, looks like someone bottomed out the truck on a trail or something. Driver side pipe after the cat looks almost flat. lol oh well. New pipes and lift here I come, actually I just saw a black z71 in my area (Evansville-ish Indiana) that had duals. Anybody know a good write up on how to get that done? Tried searching but my internet is slow atm
 
Many older threads about types of exhausts and the problems with having a dual exhaust run on an AV. Basically very few kits to do dual exhaust since clearance is tight on driver side due to gas tank and spare tire. You probably will need to get a good pipe bender and welder to make an efficient exhaust setup that fits. Then if you do lots of towing you get the noise echoing off the front of the trailer and coming back on you. Also if you have a motor that burns some oil you can get the front of your trailer dirty and exhaust stained not to mention damage to tips from backing or parking lot contact from others. Those who have done the above seem to like it though.
CAT back full systems like from Corsa are expensive but they have a lifetime warranty, hold up to road salts etc., the engineering for performance and fit is already done by them, and they are a very easy install that you could probably do yourself with no bending or welding. The also don't drone in the cab.
If you plan to keep your AV for many years they will pay for themselves over time vs. buying cheap and having to replace every couple of years.
http://www.corsaperformance.com/
 
Jwh91 said:
I might need to, looks like someone bottomed out the truck on a trail or something. Driver side pipe after the cat looks almost flat. lol oh well. New pipes and lift here I come, actually I just saw a black z71 in my area (Evansville-ish Indiana) that had duals. Anybody know a good write up on how to get that done? Tried searching but my internet is slow atm

I live about an hour and a half up I-69 from Evansville.

I bought a true dual 3" setup from Speed Engineering for a Silverado and had Bell's Exhaust in Bloomington tweak it after I "roughed" it in.  Between that and the long tube headers I also got from Speed Engineering truck dropped a half second in the quarter mile.  Before I was running JBA shorty headers, stock y-pipe, and Flowmaster 50 muffler.
 
Back
Top