Catalytic Converter removal

[WhippinCamry]

91 camry 3s fe. 4 cyl.

i know alot of you have removed the cat and replaced it, checked it out or gutted it.
im trying to gut mine/clean it whatever.

one of the nuts is really close to the block and the rest simply will not budge.
i have no power tools, thats the biggest problem.


please include pics if possible. i would pay someone to walk me though the steps if possible.

In neutral my car has a nice firm pedal nice high revs. but in drive its basically bogging, compared to the exhaust noise in neutal.

quite a few backfires also.

help!

[white90dx]

I don't have a walkthrough... but I can give you a few pieces of advice...

First - PB Blaster! Hit every fastener at least once a day for a few days while not driving the car. This will help loosen up the rust.

Second - better tools! They don't have to power/air. Often, they don't fit in tight places anyway. Use the longest/strongest ratchet or breaker bar you can, along with 6-sided sockets. Pay attention to any time you can use an extension to put the ratchet in a better place for leverage.

Good luck! Expect to break a few fasteners...

-Charlie

[holmesnmanny]

Universal joints are your friend.

[WhippinCamry]

Thank you too. I just got the pb blaster gonna let it soak at work tomrw and use the gfs dads large array of random tools and see what i can do.

i see the 3 bolts at the top and 3 at the bottom?

and wouldnt i have a power robbing exhaust leak if some of the fastners break off if i dont weld it shut?

sorry for too many questions just trying to take lessons from some of you guys, you guys know your shit on these models.

thank you-Tyler

[AnimatedMechanic]

You know, I was just thinking about this same thing the other day. How much power would this free up on a V6? I was gonna cut off the CAT and replace it with a straight pipe.

[white90dx]

Originally Posted by AnimatedMechanic

You know, I was just thinking about this same thing the other day. How much power would this free up on a V6? I was gonna cut off the CAT and replace it with a straight pipe.

Getting rid of the cat won't do much for power... on the V6, you can gain a lot (probably 10-15hp) by doing a proper header and y-pipe setup though. Too bad that is expensive (or rather, lots of fabrication).

-Charlie

[white90dx]

Originally Posted by WhippinCamry

Thank you too. I just got the pb blaster gonna let it soak at work tomrw and use the gfs dads large array of random tools and see what i can do.

i see the 3 bolts at the top and 3 at the bottom?

and wouldnt i have a power robbing exhaust leak if some of the fastners break off if i dont weld it shut?

sorry for too many questions just trying to take lessons from some of you guys, you guys know your shit on these models.

thank you-Tyler

If I was going to do this, I would take the manifold/cat/elbow off as one piece and work on the rest of it off the car.

The best way for you is whatever will break the fewest parts though.

Oh, and if you are going to get rid of the cat honeycomb, make sure you don't breath the dust - it is very carcinogenic.

You can't really weld cast iron, so you would have to fix anything you broke along the way.

-Charlie

['88 All-Trac]

Mine had a bolt shear off on the cat/manifold mating surface and does not leak.

I, too, recommend you remove the manifold/cat assembly as one piece and then separate them. Much simpler. Remove the upper heat shield from the manifold to gain access to the 6 mounting studs/nuts and blast those with the PB Blaster and let them soak for ~30 minutes to a couple hours depending on rust. Remove the nuts (you will need to remove the alternator belt and lift the alternator to get the one on the passenger side of the engine), remove the two bolts that secure the cat brace to the block, and remove the 3 nuts holding the exhaust to the cat. Pry the exhaust away, make sure the manifold/cat assembly is loose, and lift the entire assembly out of the engine bay.

I prefer to use a deadblow hammer and a 10 or 12 mm wrench for removal of the 2 nuts/3 bolts holding the cat to the manifold. On my Camrys, it was 10mm hardware but for whatever reason my brother's ST204 (I think!) USDM Celica GT used 12mm hardware with the typical 6mm shafts.

The entire process only took me a couple hours my first time with no guide on how to do it. I recommend you use a large chisel and a hammer- this is what I did and it made no dust for me to breathe.

Good luck! If your cat is plugged up, it will make an enormous difference on the top end. My mom's Camry (the '91 2wd) went from maybe 18mph highway on a good day to upwards of 34mpg for long-haul type highway driving... And I can now do 60mph in second gear. :o

Let us know how it goes! Ask me to clarify if I made anything confusing.

[AnimatedMechanic]

Originally Posted by white90dx

Getting rid of the cat won't do much for power... on the V6, you can gain a lot (probably 10-15hp) by doing a proper header and y-pipe setup though. Too bad that is expensive (or rather, lots of fabrication).

-Charlie

Ok thanks man. Makes me wish I had a pipe bender :/

[WhippinCamry]

Thank you guys for the amount of responses.

also im a bit strapped for cash so will i need a new intake gasket?
seen some online from 4 to 50 bucks. 4-10 bucks i can do but not anymore.
i also read that if u use a certain material for the intake gasket it can reduce temps and get you some hp gains.
but im guessing those gaskets are pricey.



Thanks once again.

['88 All-Trac]

Intake gasket for what? It's the exhaust manifold that comes off. Mine had no issues with leaks, but I was doing a strapped-for-cash build as well. I torqued the manifold nuts to ~3lbs over the called spec to help squish down on the old gasket... But I don't recommend this. Do Autozone or O'Reilly Auto have gaskets for cheaper? I was able to get a complete head gasket set for about $80, and that was intake/exhaust/head/thermostat/dist./you name it.

[scoathy]

+1 on PB blaster... LOTS of PB Blaster
+1 on universal joints as well.
I am missing one nut on the bottom front of my cat. the performance shop that finally resolved my NOx emissions fail advised that there was no leaks whatsoever but if it made me feel better I could add the nut to the stud that is already there and rusted up.
There is a gasket on the top and bottom of the cat. I would consider purchasing replacements if you end up removing the cat.
Large gains in performance and mpg seem to be a mixed consensus... remove the placebo effect and I would not expect much... better yet, expect no gain at all so that any gains you may get are a bonus.
GL!

['88 All-Trac]

If it's plugged, the gains are quite noticeable... A properly functioning cat should not have any effect on exhaust flow.

Removing mine made a big difference, more in the driveability and usefulness of the gears- The leading surface of my cat was about 80% blocked and the entire center section had been melted into a nearly sealed "plug" of palladium and platinum.

[WhippinCamry]

A mechanic told me its not worth the effort. but im still working on getting the heatshield off.

How do i go about disconnecting the bottom half of the cat/elbow?

Thanks once again.

['88 All-Trac]

The bottom half? I, personally, prefer to remove the three nuts securing the exhaust to the cat and the six nuts securing the manifold to the head- there are on some Camrys a couple brackets to support the cat as well. Remove those and pull out the entire assembly of manifold and catalytic converter in one piece, and then unbolt them. I couldn't find any way to remove the cat without removing the manifold, what with my fat hands, but I can do the whole job of removing it, rodding it, and reinstalling it in about an hour.