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Old 11-25-2018, 08:49 PM   #1
shultzee13
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Tearing up cat converters

98 5.7L 2wd suburban. O2 sensors brand new. Fuel test: pressure holds long after key turns off. Sub runs fine no misfire codes. I’ve replaced the cats twice and now this will be the third time. Muffler shop says there is no exhaust leaks. I’m at a loss. Plugs are not wet.
Is there a test to determine what is going on?
Thanks guys
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Old 11-25-2018, 09:31 PM   #2
82C10step
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Re: Tearing up cat converters

Mileage on them?
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Old 11-25-2018, 09:39 PM   #3
shultzee13
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Quote:
Originally Posted by 82C10step View Post
Mileage on them?
Which time? This is my third time replacing them. My suburban has 350,000 on it right now
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Old 11-26-2018, 09:13 AM   #4
95 S_Trucker
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Re: Tearing up cat converters

What is the reason for replacing them? Are they clogged? Or are you getting codes(P0420/P0430)

If they are clogged, you have another issue that is causing that.

150K is the average lifespan of an OEM converter. Aftermarket converters are typically shorter.
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Old 11-26-2018, 08:10 PM   #5
82C10step
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Re: Tearing up cat converters

Some of the cheaper ones only have a 25000 mile life span. Most all aftermarket ones will not live anywhere near what the OEM ones do.
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Old 11-26-2018, 08:32 PM   #6
shultzee13
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Re: Tearing up cat converters

Yes persistent code PO430/PO420. My mechanic just told me I don't have any misfires and not leaking any coolant. He's saying if head gasket busted then I would have misfire codes.

He's telling me ONLY OEM cats will work long term on my suburban. I have heard this before.
What say you guys?

I don't want to make a bad decision. Just looking for input.
I appreciate your time.
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Old 11-26-2018, 09:40 PM   #7
95 S_Trucker
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Re: Tearing up cat converters

I’ve had good luck with the walker direct fit converters for these trucks. They are salty.

https://www.amazon.com/Walker-50410-...59891590&psc=1
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Old 11-27-2018, 07:30 PM   #8
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Re: Tearing up cat converters

Sounds fishy to me. Even aftermarket cats should last 100k or more, they are all made from the same stuff. How much stuff is in them and resulting amount of actual conversion that is going on inside them is the big difference.
My oem cats are almost to 200,000 miles.
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Old 11-29-2018, 09:41 AM   #9
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You could be chasing your tail

Cat efficiency codes could be from many things. Not just the cats.

If you're replacing cats that many times just for a code, you should get rid of the monitoring function (along with the CEL and code) for the cat efficiency and be done with the problem.

I had used O2 sims for years to do just that but they would intermittently give a code. I eventually had PCM Forless program out the function.

Not knowing how your inspection is done there, this may not work. Here in SEVA, they do not do a tail pipe sniffer test. The cat shells are there but they been gutted.
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