Replacing CATs, DIY?

[l008com]

Is a CAT replacement in a trailblazer something someone can realistically do themselves?
While I am handy in general, I've never done this or anything quite like this before. From the look of the pictures of the new part, it looks like it just bolts right on nice and easy. Though I imagine the bolts are super difficult to get to under the truck?

More Information for WALKER 16671

www.rockauto.com

I'm kind of on the fence about doing this repair at all, but if I only have to pay for the part, and if it's something I can actually do myself, I'll probably just go for it.

 

[KEEBZ489]

in the driveway it will most likely be a pain , but doable. the bolts like you said will be the problem. break one and what do you do ??? why do you think you need a new cat ? here in the nyc area there are hundreds of muffler shops. for the $400 for a new part i would strongly consider getting a universal cat welded in if needed.

MagnaFlow OEM Grade Federal / EPA Compliant Universal Catalytic Conver

MagnaFlow OEM Grade Federal/EPA Compliant Universal Catalytic Converter 51006 helps keep the check engine light off. Get the right fit for a wide array of vehicles thanks to the adaptable Universal design (cutting and welding is required). With highly corrosion resistant, stainless steel...

www.magnaflow.com

dont know what emmisions your state needs , but from my reading is that basically all cats are the same by fed standards , california and ny require " approval " stamps /ratings , meaning that walker , magnaflow etc will submit the product for more stringent testing and when passed they can sell it as such... now the $150 cat becomes $300 because we end up paying for that CARB #

again , i may be wrong , but its what i gather from what i have read

 

[l008com]

I believe the V8 exhaust has two cats, one for each side, no? I can't imagine a muffler shop doing better than that.

Also I think I need a new cat because my downstream O2 sensor periodically comes on. My old mechanic looked at it and said its a cat. Which makes sense, the truck has something like 140k on it.

Regarding the bolts, they are flanged together aren't they? So a snapped bolt would simply release as good an unthreaded one, no?

I literally haven't even gone under my truck yet to see how it looks. I may do that today.

I live in MA so I don't have to deal with California emissions. But I do have to deal with a strict lemon law if I sell the truck today and the light comes on tomorrow.

 

[TollKeeper]

Regarding the bolts, they are flanged together aren't they? So a snapped bolt would simply release as good an unthreaded one, no?

No, because of the heat cycles of the exhaust, plus normal environment (water, heat, salt, etc), which cause rust, and threads to get screwed up, and... It can just be a recipe for a problem.

 

[KEEBZ489]

id still check with a little tiny muffler shop guy , the type you find in the auto part yard part of town , not a midas or anything , have you changed the downstream AND upstream ? rule of thumb for me is if i get a downstream code , new oem quality sensor , not an ebay $15 one , if i get the code again shortly after i swap all the sensors. cheaper than a new cat , your upstream helps determine what the engine is burning air/fuel wise , a bad mix can cause the downstream to pop up because it knows what its reading but getting bad info readings back. last is a cat replacement. 25 years driving ive only had 1 cat go bad and that was from physical damage and bad placement design