Catalytic converter?

The one cat I had to pay for I ordered from Rockauto. I think it was a Walker for around $150. It was fine and I never had a problem with it. The one GM paid for of course was an OEM for $700.


How long did you keep the car after you installed the Walker cat?

@db4690 I’d have to go look it up but it was at least 3-4 years. The records are in my archives. The original one just rusted off finally.

I’ll go against the grain here and suggest replacing the downstream O2 sensor first. At 210K miles, it has to be pretty tired, and you’ll need one anyways. You have nothing to lose by trying it first.

If getting that O2 sensor out is stubborn, then try heating up the base of it with some MAPP gas. It will come right out.

Again, a lot of great information for me. Ideally, can anyone tell me what the before and after readings should be? Right now it reads:

O1 Sensor between .330-.800, fluctuating between the values and mostly between .500-.800
02 Sensor between .300-.855, mostly between .400 and .800

Unfortunately I cannot monitor both sensors at the same time because I have to hit a button to scroll to the next screen to read the O2 sensor and the O1 is off the screen. So there is a little delay by the time I switch back and forth.

I will be replacing the upstream sensor today and add this “magic” cat cleaner stuff to the next tank of gas. If that does not help a new converter is next. It’s just a little slow process because the check engine light does not come on right away, but may take 1 or 2K miles after a reset of the code…

My old converter is bolted between the pipes, so I expect it to be an “easy” replacement even if I have to saw off the old bolts…I just hope the length of the new converted is the same as the current one. That’s what I would call a direct fit. Since I am in Maryland I believe have less restrictions as to what brand/type of converted I can buy.

I will be replacing the upstream sensor today

On Nov 11th, you said that you already replaced the upstream O2 sensor.
Don’t you mean “downstream” O2 sensor?

@db4690 OK, checked the records archives. My memory was a little hazy. It was actually a cat from NAPA so not sure what brand but think it was a Walker for $140. I replaced it on 9/30/05 at 364,464 miles and dumped the car on 4/30/10 with 523,000. So I got about 5 years and 158,000 out of it but it was still good. The only thing I remember is that it bolted right up but it may have been about 1/2" or so shorter than the original. I dunno but there was a little rubber O ring hanger in the center of the car and instead of hanging straight down, it was stretched some. So I would have to replace the O ring every once in a while when it broke. I used to buy a couple at a time for 50 cents at NAPA. Took about 5 minutes so wasn’t worth trying to figure out a better way.

oops…yes, JoeMario, the downstream.


The reason I asked is because I installed a Walker y pipe . . . once

It looked good, but didn’t last but a few years, before it literally disintegrated

Now I’m not recommending this. Definitely not. But I have to wonder if anybody – trying to extend the life of their car’s expensive cat – removes it as soon as they pass the emissions test, then bolts it back on for the next test?

"even if I have to saw off the old bolts"
That’s the accepted procedure. I don’t know anybody who doesn’t just cut the bolts… usually with a “cut off wheel”… or something similar. Except for me. The first time I change one of my exhaust components, I replace the OEM nuts & bolts with stainless steel, with antiseize applied. Ever after, they come apart as if they were brand new. I once changed the entire catback system in my old pickup in 20 minutes flat (no exaggeration).

A “direct fit” WILL bolt right in. Be sure to get the “doughnuts” too. Those are the doughnut-shaped metallic (used to be asbestos) “O-ring” gaskets that go in the joints.

NOTE: look at the joints ahead of time. If they have springs, they’re “flex joints”. Be sure you have everything you need, including the correct torque value. The local dealer’s parts guy should be happy to give that to you upon request.

I replaced the exhaust on the kid’s Acura and just cut the bolts with the angle grinder. That’s the easy way. Just had to make sure I had the right bolts on hand at night.

Now again, I know that was a Walker that I ordered from Rockauto because I was surprised that the long pipe came UPS no problem. I have no records on that one though so can’t remember if it was the full cat back with the muffler or just the exhaust pipe. It lasted until the car was wrecked but can’t say how long that was. At least two-three years though.

I just don’t know if Walker is any better or any worse than the after-market stuff. I do know though that way back I got an exhaust pipe for the 74 Olds from the dealer and the metal was quite a bit thicker than the after-market stuff so guess you get what you pay for.

I too use an angle grinder with a cutting disc on it.

To the OP: be certain to use eye protection when using a cutting tool. I generally wear a full face mask. Cutting tools spin at very high rpms, and they throw a lot of particulate matter everywhere very quickly. I can pretty much guarantee that you’ll get debris in your eyes if you don’t protect them.