Yep, another issue. This time it's an exhaust questions

[mntb]

My tb ext 5.3l has developed a rattle coming from the driver's side cat on top of other issues that are popping up as well. It not a heat shield. I already have had to re-resecure the passenger side heat shield which is why I was poking around under the TB in the first place. Btw, the truck idles a lot for work, can I simply remove the one heat shield and be OK or will the heat be too much without the shield and little air movemeant at times under the truck?
Are the exhaust manifolds separate from the cats and y pipe?

My question is this:
What kind of options am I looking at?
What would you do?

First thought, was to find a shop that will cut the cats out and weld in a pipe. Here in mn we don't have emissions testing.

Second thought, have them replaced which I'm guessing means kind of costly.

And third, headers? But it looks like it's kind of a pain to remove/install the exhaust manifolds. And headers are out of my price range right now i believe.

I don't have a lot of money. I don't have access to a welder. This will probably have to be done by a shop for this. I have to fix other issues too so this is a little lower on my priority list. And I will be moving in a few short months, maybe weeks. Also, it can't be too loud as I use it for work making deliveries early in the morning(2am-7am). I wanted to put a different muffler on it before this to give it a little tone to the exhaust as well.

If I leave this alone will it do any damage? Or just annoy the piss out of me like it is now.

Any thoughts or advice is appreciated.

 

[Sparky]

Manifolds are separate from cats and Y pipe. I think the Y pipe and cats are 1 piece though. You could have an exhaust shop weld in a universal cat probably.

If the cat is rattling, it won't hurt anything necessarily, although there is a chance that the guts that are rattling could break up and either plug up the cat (in which case it would start running like crap) or it could just jettison the guts of the cat through the exhaust and throw a SES light for no cat function. Likely though, unless the guts are in really bad shape, they'll just rattle.

 

[mntb]

I didn't even think of the universal cat idea.
I thought maybe I could find the cats and y pipe in a salvage yard but I have yet to see a 5.3 trailblazer. All I have seen are 4.2 equipped TBs, Envoys, etc.
I wasn't sure if the manifolds were part of the y pipe/cat section. I didn't look that far up the exhaust.
Thanks for the reply.

 

[Reprise]

I didn't even think of the universal cat idea.
I thought maybe I could find the cats and y pipe in a salvage yard but I have yet to see a 5.3 trailblazer. All I have seen are 4.2 equipped TBs, Envoys, etc.
I wasn't sure if the manifolds were part of the y pipe/cat section. I didn't look that far up the exhaust.
Thanks for the reply.

You might try looking for an Envoy in Denali trim - I think (?) those had the V8 as standard. Not sure if the Y-pipe is the same on SWB vs LWB, but they did have the Denali trim on the LWB as well - and they do pop up fairly regularly, at least in the Chicago Metro area. Not sure how the pickings are in MN.

On your other options... if you're moving outside of MN, do you know the emissions testing in your new state? If not - I'd put a replacement stock Y-pipe with the cats in.

You need a fairly quiet exhaust, given your work activity - I'd steer away from headers, then.

Finally, if you stick with a stock replacement strategy, there's a good chance you'd avoid welding, and might be able to DIY. You'd have to remove the O2 sensors, so you'd need the special socket to remove them with. You'd have to remove at least 2 of the 4 (I'd need to look at a diagram to see whether you'd need to remove two or all four).

If you have access to some sort of electric impact wrench, it may help in getting the replacements off at the pick-n-pull. Even so, I'd go out there with a can of Liquid Wrench or equivalent, at least a day or so before you plan on removing them. Also, as I recall, one of the three bolts at the exhaust manifold to Y-pipe connection will be very hard to get to. Take a look at the connection on your vehicle before you go out to the salvage yard - make sure you have whatever extensions / universals you need when you go. The alternative would be something like a sawzall - but there's very little room in that area to get a blade in there.

A brand new Y-pipe with the cats looks like it will run $350-400. Probably more than you want to spend - you'd save removal of the one from the donor vehicle this way.

 

[mntb]

I wont be moving out if state. Just relocating within the state.
It's rare to find a Denali envoy in the junk yard. I have yet to see one. Around here trailblazers/envoys are hard to find as it is.
$350-$400 is definitely a little steep for stock replacements. Are the stock cats restrictive or do they flow pretty decent? I'm going to talk to a few smaller exhaust shops that I know of and see what it will cost to have the two cats replaced with aftermarket, stock, or high flow(if thats even worth it) cats.
The problem now is I believe both cats are broken apart inside. And from time to time I can hear and feel the chunks clogging the exhaust. A few times I've had to pull over and pound on the cats a few time to get the pieces to move.
If I were to just hack them out myself and put straight pipe tubing in their places. How much louder might it be? I looked on YouTube a little, but a lot of the videos have no cats and aftermarket mufflers.
The truck can have a some rumble to it. It just can't be insanely loud like a full straight pipes or no exhaust setup would be.
I would love to have a dual exhaust installed if I had my way.

Thanks for the ideas and suggestions.

 

[Sparky]

It wouldn't be too much louder since you'd still have the muffler. But you'll throw a SES light for non-functional cats (won't affect how it runs), and the exhaust might smell bad. My Camaro might not have functional cats and it might smell like an old farm tractor

 

[mntb]

Lol, "might".

Will a no cats effect fuel mileage (not that there is such a thing as good fuel mileage when doing what I do)? She will run rich?
What do you mean by "bad smelling exhaust"? The exhaust smells like gas?

I have heard about using spark plug Anti-Foelers (whatever those are) or something to do with the o2 sensors to trick the computer into believing the cats are still in place. I haven't looked into this yet though so I'm not sure exactly how it works or if it would work for the tb.

The guts resting on the bottom of the cats is driving me nuts. Especially when I have to leave the driver's window down for a period of time for work. Makes the TB sound like a piece of s#!t hopty.

 

[Sparky]

All the fuel mixture stuff is controlled by upstream O2 sensors which are before cats. Cats (or lack thereof) will not affect fuel mixture.

Exhaust without cats will smell kinda funny because of the other stuff now not removed from it. Kinda smells like fuel, yeah, but not quite. It is a bit of its own smell. If you were close by I'd say swing out here and huff my Camaro's tail pipe to get an idea

The non-fouler trick can work perhaps, because it backs the sensor out of the main exhaust stream and might be enough to trick it. Thing is, I think that usually only works with a marginal cat converter, not a totally removed one (but I could be wrong). My Camaro has the rear O2 sensor totally tuned out of the computer.

 

[mntb]

Thanks for the explanation. So the anti-foulers acts as a spacer for the o2s basically.
I have noticed the exhaust had a little different smell to it just by passing by the back of the truck. Kind of a weird smell I can't put into words. It's not too strong, just enough for me to notice.
I just have sneaky feeling it's going to cost me more than I have to spend to fix this the "right way".