Newly Installed Used Engine Eating Up Cats

[rcox58]

You may have seen me make mention of this in a post about an aftermarket exhaust. Don't mean to be repetitive but I'm looking for more specifics on this problem.

My original cat failed and led me to detecting a bunch of engine problems that turned out to be fatal. I had a new cat installed literally weeks before my stock engine failed. I had a used engine installed and the cat promptly failed. It was a universal fit that I bought due to cash flow issues. Of course it was under warranty so when the Napa shop was making good on the replacement I upgraded to the suggested direct fit but now the car ate that one up. It's a Walker so it's also covered under their warranty. I just had the car in the shop that installed the used engine and was advised that the car isn't throwing any codes or tripping any sensors (Is that the right phrase?) that would indicate a running problem that would cause it to eat up these cats. I haven't taken the cat off yet to see if it's just broken up inside or if it's melted so I know that might tell the story to a certain degree. I just wanted to check in here for the expert opinions because I'm always wary that a shop will convince me it's not their fault just because I don't know better.

A little about the used engine. The car seems to be running great with the exception of a slow oil leak/burn at a rate of about 1 qt every 1,000 miles. The shop said the supplier of the used engine can't and didn't warranty it against burning oil and a quart of oil every so often is a small price to pay for a used engine that is otherwise running good.

Any thoughts? I know Walker is one of if not the bets cat manufacturers so I don't know the likelihood that I just happened to get a couple three bad ones? Is there anything I need to know before I go back to Napa, the Meineke that installed the cats or the shop that installed the engine? I certainly can't afford to keep paying labor to install cats even if the part itself continues to be replaced under warranty.

I appreciate any help.

[repinS]

Moved to 2000-2005.

[rcox58]

Sorry...that's where I meant to put it

[myfirstbonnie]

What are your indications of a bad cat?

To check the current cat, get the car on ramps or stands and either kick the cat or bang on it with a rubber or soft mallet. If it rattles, it is definitely bad.

The motor burning a quart of oil every 1ooo is not good either. Burning oil will foul the plugs and cause other issues. Go have the codes read and see if there are any in the history? Does the CEL light come on when you start the car (making sure it actually works)?

Excess fuel in the exhaust will cause the cat to burn it off and it will get hot and burn itself to death. You want the fuel to burn in the cylinders not in the cat.

[yourgrandma]

I wish my engine ate cats. Meow.

[MattStrike]

If it's throwing the code for the rear O2 sensor, how I'm guessing you know the converter is bad, then it's likely the wiring or the sensor itself has failed.

If it glows cherry red then unburnt fuel is getting to it.

[BonneMe]

1 qt over 3,000 miles is tolerable on most street engines, 1 qt every 1,000 miles is downright excessive. If you're burning it that's probably what's clogging up the cat, is there any visible smoke from your tailpipe?

[rcox58]

The cat is definitely bad. It rattles while the car is idling and, of course, while driving. The shop that installed the used engine confirmed that it's bad on two separate occasions but hasn't pulled it off to see if it's just broken up inside or if there's any sign of burning. After my post, that shop did say there's a "small" oil leak that is where the qt per thousand miles is going so it seems it's not really just burning it. There is no smoke coming from the exhaust that I can see but I am getting the spoiled egg smell.

I'm beginning to distrust the shop that put in the used engine so I don't want to ask them for much else. (I have terrible luck finding a shop that doesn't rip me off.) It was a Meineke that installed this and previous cats. Maybe I need to take it back to them to diagnose?

In another post, I wrote about looking for an aftermarket exhaust that makes the car sound good. I'm thinking of replacing the cat with a straight pipe and a FlowMaster or something anyway but I don't want to ignore what's causing the cats to go bad.

[myfirstbonnie]

Can you trust this shop enough to know they installed a new cat? Maybe they charged you for it, but never installed one.

[RogueSSEi]

If it was me I'd say fuhck meinke, order a magnaflow high flow cat for like $60 of eBay from ZZP, take it to a muffler shop have them install it and keep your cat and sale it at a recycler.
Burning 1 quart oil and no smoke, sheeut sounds like their barebackin' you. At least ask them for dinner.