2004 Mercury Grand Marquis catalytic converter - got quote - need feedback, please


#1

It has roughly 169k miles. We took it in to investigate a rattle. Mech says it’s a piece of ceramic that’s come loose in one of the car’s 4(!) catalytic converters, and one needs replacing. A brand-name part is $950, but the after-market one is $450. Labor is $190. We’re located in Houston, TX. I’m thinking of going with the $450 because I’m not sure I see $500 worth of extra value in the brand-name. Agree or disagree?

Next question. Mech says that while he’s in there, I may as well go ahead and replace BOTH O2 sensors on that cat converter. He says it’ll eventually need to happen anyway, and if I do it now, there won’t be any additional labor (since he’s already opened it all up). Each of these O2 sensors is around $80. Should I do it now?

Last question: the inspection isn’t due until November. The car is currently running fine. If I put this off until November, will the problem somehow get worse and end up costing me more?

Thanks so much you guys.


#2

$450, O2 sensors yes, Postpone, yes…

In November, if your check engine light is not on, the car will probably pass the test regardless…I would wait until it failed the test before I spent the money if you can tolerate the rattle…


#3

I agree with @Caddyman‌

There are no rules that say a car with a noisy cat must fail

Main things . . .
No check engine light on
Check engine light isn’t being commanded on . . . not exactly the same thing as the first, actually
Emissions equipment is present, and hasn’t been tampered with, or disabled
Emissions equipment is actually operating . . . just because EGR is present doesn’t mean it’s working, for example
Requisite number of monitors are complete
Pass the tailpipe test

There are a few others, but those were the most important ones


#4

With no safety or drivability issues, I’d wait until just before the test to address this. If I was doing this work myself on my own car I wouldn’t replace the O2 sensors, but the labor rate when I do it is at most a cold beer. In your case it probably makes sense to replace the O2 sensors. Tell your mechanic you want to keep the old ones though, they are probably still good and may come in handy at some point.

Re; the cat. Cats are made with expensive materials, and there would be a profit reason for a manufacturer to skimp on the amount of that stuff they use in their products. But I’ve never seen a functional test of the various brands of cats, so I don’t know if the price of the cat is related to that or not. You’d need to have that data to know for sure, but I doubt it is available. You might try Googling for it though, comparing the two possibilities. One thing, make sure your local/state laws allow you to use the particular cat you choose in the end. In Calif only certain cats are legal to install.


#5

I’d go for the $450 converter as long as it’s a “direct fit” unit and stainless (which I think they all are now). Since you haven’t mentioned a CEL light, I’d skip the O2 sensors for now. Although I have to admit that he’s right about the labor, the sensors simply screw into threaded bung holes in the pipes. The labor to replace the sensors should that ne needed isn’t that great.

One caveat: if he breaks a sensor during the replacement, don’t hesitate to accept replacing it as part of the job. They sometimes have a tendency to bond themselves to their installation holes for all eternity. It’s all that heat, you know.


#6

My f150 has a rattley exhaust, both a bad muffler and cat, but theres no check engine light on and it runs fine so I live with the extra “music”.

I had a mustang where one went bad and it sounded like marbles in a coke can. Too annoying to live with. That one I replaced.

The first cheapest option is to take it to a muffler shop, have them hack out the bad cat and weld a universal one in. Thatll probably be in the neighborhood of 150-200 id say. Thats including labor and parts.

Next you can replace the whole midpipe for 450 plus labor. Leave the sensors until they go bad, and individually replace the specific one that goes bad if and when it does.

I see this scenario all the time on this forum where a cat goes bad and the shop tells them they need to replace the whole midpipe, with all new cats for a grand. Sure, thats ideal, but you’re not driving around a car with 150k plus miles because you have money. By the way, they make money selling your bad, used mid pipe. I know because I did it myself when I swapped a high performance one on my mustang. I think a guy gave me 60 bucks for it or something. The whole old mid pipe. The metals are worth $$$. When one of those cats went bad I replaced just the cat, not the whole pipe. Same with my sisters old land rover. You can imagine what they wanted for a whole new mid pipe. We had it hacked out and had a universal one put in, and no problem for years after that (not with the exhaust anyway!)

The argument against doing that is that if one cat has gone, others cant be far from failing too, but i say roll the dice. If and when another goes, replace that individual one too. Could be 6 months could be 2 years.


#7

Ya know what? Having just looked at your exhaust on Rock Auto its not a connected H or X Pipe. Its one pipe with 2 cats on one side and one on the other. Rock auto has them for 160ish for the whole pipe with 2 cats. They also sell them up to 450 but those are for California cars. Dont pay 450 regardless, unless you live in CA.