Replacing the cat question?

WeaponX

Original poster
Member
Mar 23, 2019
212
Pittston, PA
Ok I got a new cat same as the factory, got the new O2 sensors (was getting codes they were bad, not sure if it is just the absence of a cat but I’m changing them anyway) both upstream and down and I just replaced the donut gasket about 4 months ago at the manifold junction.
So my only question is is there a gasket at the junction after the cat? I’d rather get it now than have to go run and get one after it’s ripped apart.
I’m hoping my idle (which is at a constant grand) and all the power loss and any small issues left over after I replaced all the fuel injectors go away.
Actually I lied I have another question is there a special tool for the O2 sensors?
 

Mike534x

Member
Apr 9, 2012
1,019
There's a socket made for removing O2 sensors, it has the cutout already for the wire to slip through/out of the way. Not sure about the gasket for the cat however. If your idle is at a constant 1K, it sounds more like a possible vacuum leak if anything.
 

mrrsm

Lifetime VIP Donor
Supporting Donor
Member
Oct 22, 2015
8,267
Tampa Bay Area
These Oxygen Sensor Tools are available on Amazon:

O2SENSORTOOLS.jpg

Ordinarily... There is a Bell Shaped CAT back Pipe that fits over the "Ball" Shaped end of the CAT that are held tightly together by a Special Stainless Steel Clamp. This thing has a Half-Moon hollow interior shape, fully 360 Degrees around that encircles the CAT Ball End to the Bell shaped opening of the Pipe and mates them up while squeezing them tightly enough together to preclude any escape of Exhaust Fumes. Unless you abuse and damage the Fastener on that Clamp during its removal or re-tightening ...it should be re-usable during this R&R.
 

Maverick6587

Member
Dec 16, 2018
730
Sterling Heights, Michigan
I would buy that Ares 70039 that MRRSM posted above.
I tried to use that TEKTON 4929 and I couldn't get a breaker bar on the socket. There wasn't enough room between the O2 sensor and the wheel well.
 
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TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,265
Brighton, CO
I would buy that Ares 70039 that MRRSM posted above.
I tried to use that TEKTON 4929 and I couldn't get a breaker bar on the socket. There wasn't enough room between the O2 sensor and the wheel well.
Agreed. It seems to be the better socket for any tight spaces.
 

budwich

Member
Jun 16, 2013
2,203
kanata
I would make sure that any socket that you get / use IS a 22mm and not a 7/8 /22mm as the "combo" is a "fake 22mm" and is larger than spec of the nut. With the "slit", with any effort, the socket will just spread enough to spin on the sensor.

My best method for removal is propane torch the nut / base while you throw your wrench / socket in the freezer. Once the nut has been "almost glowing", put your now "ice cold" socket / wrench on it. The thermal shock will likely break things free with less wrenching effort.
 

Mooseman

Moderator
Dec 4, 2011
26,107
Ottawa, ON
I made my own socket with a 22mm impact deep socket that I cut a slit into. So far fits on both GM and Asian sensors tight is it should. The 7/8 sensor sockets usually strip the hex as it is just a little too big.
 

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