My catalytic converter took a dump UPDATE: it wasn't the catalytic converter

[meow2u3]

Last edited Wed Jul 12, 2017, 03:32 PM - Edit history (1)

The power on my car has been weak for about a year and I thought a tune-up would restore both the power and gas mileage. Friday, I started to smell rotten eggs from the exhaust; that's when I knew the problem was the catalytic converter. The repairs would have cost me about $600.
https://www.gofundme.com/catalytic-converter-replacement

Any help would be appreciated. No, this is not a scam; I'll scan and post receipts as proof.


UPDATE: I took my car to Midas today for an exhaust check. The loss of power turned out to be caused by a clogged fuel system, not a clogged exhaust system as I previously believed. And the strong smell came from a bad battery, not my catalytic converter.

[physioex]

1. Hmm...I had the same issue with my car.

But I was fortunate, I happened just before the warranty ran out, and It turned out I had to pay nothing for the repairs. Emission equipment has different warranty than powertrain and is mandated by the government.

[Dr Hobbitstein]

2. What year is the vehicle?

If it's old enough (pre-computer controls), and you don't have emissions testing, just removed the cat and put a straight pipe in it's place. I did this on my old Nova when the cat crapped out.

[Purveyor]

3. I punched through the one on my '94/Yukon. They call it "broomhandling" but it was

far from easy getting all that shit out.

Benefit of doing this is it still appears as though your converter is still intact.

Michigan has no inspections but Texas checks for it.

[meow2u3]

10. Pennsylvania checks for emissions, with one exception

If you've racked up fewer than 5000 miles in the year prior to the inspection, your car is exempt. That might be the reason I passed inspection when I should have failed.

[mahatmakanejeeves]

12. I wish they did that in Virginia.

Last edited Mon Jul 10, 2017, 09:08 AM - Edit history (1)

It's good for owners of old cars or for people who don't drive much.

Are you sure this is worth the effort?

Why bother?

[meow2u3]

8. Isn't that illegal?

My car is a 2003 Pontiac Grand Am. It's too new to put a straight pipe in place of a cat (which belongs under the car) because it's illegal.

IDK if a catalytic converter fail triggers a check engine light on a 2003, but I do know that when my car is warmed up, it smells as if it cut a massive fart.

[Best_man23]

4. If you're in a state that performs emissions inspections

You're going to have to replace it at some point.

If not, then go with the straight pipe option. Bear in mind some shops may not take the job as they don't want the potential liability.

[IcyPeas]

5. I thought this was a cat thread..... /nt

[MineralMan]

6. Check aftermarket replacements, but only if you're not in a state

that does emissions testing. You'll save big time, and the car will run better. The trick is that there's not much "catalytic" in them, but they have the O2 sensor fittings, etc. If you're at all handy, you could probably do the replacement yourself.

Google catalytic converter aftermarket replacement {year} {brand} {model}. Make sure you see the words bolt-up fit or something similar. Don't go generic. Get one that is designed for your vehicle if you're going to replace it yourself.

[mahatmakanejeeves]

7. Year? Make? Model? Engine? Odometer reading? Emissions inspections where you are?

Near an AutoZone or equivalent?

I'm trying to think why the smell of rotten eggs is a diagnosis of bad catalytic converter.

Full disclosure: I've replaced one. Years ago, in a car that has really basic emissions control hardware.

Thanks.

[meow2u3]

9. 2003 Pontiac Grand Am, 2.2L engine, 96K miles

I just had my car inspected 2 months ago, but was exempt from emissions testing because I racked up fewer than 5K miles in the past year. That's how emissions inspections work in PA.

I live about a mile from an Auto Zone. I just went there to have an OBD2 diagnostic check. No problem was found--yet.

[mahatmakanejeeves]

11. Don't be afraid to get a second opinion.

Say, from an Advance Auto or a second AutoZone. Those scanners don't always agree with each other.

Make note of what scanner was used when you get an OBDII test.

Rotten eggs -- still thinking about what that means.

Don't spend the money yet.

Also, you can get an app for a tablet that works with a connecting cable and readout device that will let read codes and display operating information without a scan tool. Scan tools aren't that expensive regardless.

Do you have a vacuum gauge? You might find it productive to run an intake manifold vacuum test. Vacuum leaks are not uncommon in cars with extensive emissions control components.

Best wishes.

[Best_man23]

13. I would get a second opinion.

If the cat was dead, I'm surprised the PCM (powertrain computer that manages the engine) did not store one or more codes. There is a code that sets if the O2 sensor behind the converter reads insufficient oxygen.

Caveat, long distance diagnostics are sketchy at best

[jmowreader]

14. If you don't mind getting dirty, you can do it for half that

You need a Walker 54692 catalytic converter. (Until I saw what engine you've got, I was sitting here hoping it was a V-6. No such luck.)

Amazon sells this converter for $251.41. Order one and the two gaskets it needs - Walker 61643 for the front, Walker 31311 for the back, plus a downstream O2 sensor. (This is VERY VERY important: there are two O2 sensors on your car, the upstream one (in the exhaust manifold a few inches from the engine) and the downstream one (behind the cat). They're different, and almost all of them on Amazon are the upstream one.) Go to the nearest auto parts store and buy a set of muffler nuts (which are like muffler bearings, but those are purple) and washers, a tube of O2 sensor antiseize compound, and a can of PB Blaster. Find a set of jack stands and a floor jack.

Once the muffler arrives, jack up the front of your car and support it on stands.
Crawl under with the PB Blaster. Find the converter. (It looks just like that huge thing you got from Amazon.)
Lay newspaper out on the ground. Spray PB Blaster on the nuts holding it in until the fluid streams off.
Get out and go away for twenty minutes.
Go back under with the can and a hammer.
Give each nut a good whack and spray it again. (This lets the fluid get down into the threads.)
Go away for 20 more minutes. During this period, set the converter, gaskets and nuts where you can reach them from under the car. Put antiseize on the O2 sensor threads and screw it in. Then take a 7/8" wrench and tighten the living shit out of it.
Go under with a box-end wrench the same size as the nuts you bought and g-e-n-t-l-y!!! loosen the nuts so you don't round them off.
Unplug the O2 sensor.
Slip the old converter off the studs and shove it out from under the car. Remove the old gaskets from the studs and put the new ones where they were. The front one has three bolt holes and the back has two so you can't mix them up. (The old back one might look like a metal ring set in the exhaust pipe. If that's what you've got, just remove it.)

Now for the fun part. Put a little antiseize compound on all five studs. Grab the converter and orient it so the holes in the front flange are arranged the same as the front studs. Slip the back flange on its studs and loosely install new nuts and washers on the studs so the converter doesn't fall off. Then raise the converter up, push it toward the back of the car, and slip it on the front studs. Install nuts and tighten the shit out of them. Hook up the O2 sensor. Crawl out from under and start the car. If you don't hear any exhaust leaks, you're almost done. Put the car back on the ground.

The final step is to find a company that buys used converters and sell them the old one.

[meow2u3]

15. I can no longer fix my own car

I don't have the tools in which to do so.

[mahatmakanejeeves]

17. $600 buys a lot of tools. I don't know if working on cars is now a physical challenge for you.

In which case, no amount of money can do anything about that.

[mahatmakanejeeves]

16. "Put antiseize on the O2 sensor threads and screw it in. Then take a 7/8" wrench and..."

Wait. That won't always work. I'll bet it almost never works.

I had to replace an O2 sensor on a 2000 Saturn in March 2016. That car has a V6, so it had four O2 sensors. The one I replaced turned out to be the most easily accessible. Even so, there was no room to turn a 7/8" wrench, or whatever size mine called for.

I got my sensor from AutoZone. There's one within walking distance, I like the people there, and the price was competitive with buying online. What really iced the deal for me is that AutoZone lends tools when you buy parts from them. Removing and installing that O2 sensor will surely require the use of a special socket. AutoZone lent me the socket set. Only socket in that set worked on the sensor. Yes, I can buy that socket. In fact, I have an O2 sensor socket, but it didn't fit the sensor that fits the Saturn.

I have no experience working on the car in question in this thread, but I'll bet there's no room for a 7/8" wrench. Also, there is a correct torque value for that sensor, and when you use the special sensor socket, you can tighten the sensor with a torque wrench.

By the way, is there not a correct torque value for those studs?

I concur on using antiseize, but: remember to back off on the torque just a little, as the antiseize will not let the torque wrench sense the drag on the threads. Maybe 20 percent. The sensor's not coming out.

[jmowreader]

19. The spec is 33 lb-ft...finger tight plus three-quarters of a turn.

Here's the beauty about this O2 sensor: it's screwed into the side of the exhaust pipe behind the converter. (This lets the OBD2 system know the converter is still working right.) A 7/8" open-end wrench or flare wrench will work great here. The one screwed into the exhaust manifold where you can't get to it with a regular wrench? Eight bucks at Harbor Freight will be a wise investment.

The "official-ish" torque spec on an exhaust nut is 15 lb-ft...what I normally do is get a regular-length combination wrench, run the nuts down finger tight, then tighten them until they're "good & tight." Then I start the car and listen for exhaust leaks; if I find any I tighten it a little more until the leak stops.

[meow2u3]

18. I had the cat checked and am about to take it for a 2nd opinion

At my local mechanic, they didn't duplicate the power problems which I think it the cat. The problem worsens when I run the air conditioning. What they did find is a rotting gasket between the cat and the resonator.

I'm going to take the car for a second opinion. The guys I took the car to are not specialists.

[jmowreader]

20. Rotting gasket? Might be worthwhile to have that changed first

A decent mechanic can do it in five to ten minutes, and the gasket is less than $10.

[meow2u3]

22. Actually, it's a rotting flange

I saw it myself. Rust up the wazoo right between the cat and resonator.

I'm going to seek a second opinion; it might not be the cat after all. It could be the muffler and/or exhaust pipe from the looks of it.

[jmowreader]

23. Bad news...

On your car, the cat comes as a unit...the cat front flange, cat entry pipe, cat, cat exit pipe and cat rear flange come as a single welded piece. It's more reliable and easier to change, but also more expensive.

[Rhiannon12866]

21. You have a Pontiac!

So do I, my Grand Am is 2001. It's been a great car, I'm bummed out they stopped making them. Hoping you're able to get it fixed soon.