Bad cat in a 97 Olds w/only 55k miles. Causes?

[aquariuscsm]

My gf`s dad is thinking about buying a 97 Olds 88 that has only 55k original miles. The car is from the Baytown,Texas area. He did a Carfax on it and nothing came back weird. It has a bad cat. What would cause a cat to go bad on a car with on 55k miles? Is this a red flag and should he walk away from this one?

 

[Chris142]

There is a reason that the converter died so soon. Might be simple like a bad 02 sensor or a problem such as oil or coolant getting into the cat.

Is the milage documented? Could the miles have been rolled back somehow?

 

[bretfraz]

Cats don't commit suicide. They're murdered. Gotta find out what killed the cat. Chris is on track with the bad sensor idea, among other things.

 

[daves87rs]

[censored]/old gas maybe? Sounds like it was not used much. Bet you it did a bunch of very short trips.


I would say replace the cat-any sensor that needs to be replaced after that-and enjoy.....

 

[eljefino]

If you get this beware aftermarket cats have way less "stuff" in 'em and you may have to replace every other year right before inspection time. Or source out a good used cat.

I would bring a code reader with you to check it out, and make sure all the I/M monitors are done and ready except for the obvious cat one and other dependent ones. (Get a flow chart) A shady seller could clear codes before offering for sale.

 

[mechtech2]

If the car ran rich because of a bad sensor or injector, it can puke the cat.

 

[JTK]

Yep, excess fuel loading from a misfire is the most common, coolant getting into the combustion chamber, or silicone (spray) poisoning. Maybe long term use with a bad O2 sensor could cause it, but I've never seen an O2 sensor make that drastic of a fuel trim change.

Joel

 

[Eddie]

Is not Texas one of the states where certain stations were geting leaded fuel by accident?

 

[bdcardinal]

Originally Posted By: Eddie
Is not Texas one of the states where certain stations were geting leaded fuel by accident?


i wish i had that problem. my Volvo hates 91. the one time i filled it with VP 100 it ran so much better.

 

[andyd]

excess fuel is the usual cat killer. Replacing the cat wont help much if you dont fix the root cause. A buddy of mine claims to have rejuvenated a cat by running the engine for a short period of time with the vacuum to the fuel pressure regulator off. This induced a rich mixture. Then he fixed the leak and drove the car for an hour or two at speed to get the cat hot enough to cook off the gas n the cat. The trick, I'm guessing is to get the cat hot enough to burn off the carbon , but not to melt the porceline core.

 

[sciphi]

Coolant combusted? 97 Olds 88? 3800 V6? Bad intake manifold gaskets, perhaps?

 

[mechtech2]

andyd - Why induce crud in the cat, only to try and clean it out????

 

[eljefino]

I've heard of ECM programming that deliberately loads the cat with a measured amount of fuel.

1) a misfire on warming up, to warm it up faster
2) AFR of 9:1 at WOT, more than is needed for power enrichment/knock retard

May be something to it.

 

[ted s]

in NY salvage yards cant sell used convertors.