Catalyic Converter

dadejak · January 6, 2004

I have a 95 GMC Z71. How long do catalyic converters last?

With 96K miles on mine, should I go ahead and replace it with a high flow when I have the dual exhaust installed?

Thanks!

Jack

Ben · January 6, 2004

SMOG components have two min life spans dictated by EPA.

Small stuff is 2yr/24K miles.

Major stuff is 80K miles.

CATs are major component and is warranted 80K miles by the manufacturer.

CATs that cost less than OEM usually last in the 10K-20K range. Some go 30K. According to my muffler guy. Known him over 20 years, so trust him.

JayMan · January 9, 2004

Three things will quickly ruin a catalytic converter:

1. Rich mixture, usually caused by ageing or clogged O2 sensors. Neglect the O2 sensors and you'll ruin an expensive cat, as the cat will run so hot it'll melt down.

2. Wrong fuel. Obviously, leaded fuel will contaminate the metals inside the cat. Using a fuel heavy in sulfur or phosphorous will also lead to early catalyst failure.

3. Oil consumption. Oil burning motors will plug the catalyst.

If you keep the motor in good condition, such as proper tune ups, and change the O2 sensors every 60-80,000 miles, the cat should last +150,000 miles.

Another good reason to properly break-in the motor and to use a good synthetic motor oil is to reduce oil consumption. After 40-60 quarts of oil have gone through the cat, it's finished.

Those folks with the Vortec 8.1 that use a quart every 1,000 miles won't get too far on their cats. Their O2 sensors will also die early.

If the dealer can prove neglect and/or lack of maintenance caused the cat to fail, you're SOL. EPA regulates all cat converters sold aftermarket, so they have to meet the same standards as OEM.

FWIW: I average 1 quart per 4,400 miles running Mobil 1 0W-30 in winter, 1 quart per 6,400 miles running Mobil 1 10W-30 in summer.

Bluesman123 · January 10, 2004

Jayman's right. There's no reaosn your cat won't last at least 100K miles unless you abuse it. O2 sensors are cheaper than cats ... no...they are MUCH cheaper tha cats especially for our trucks. 97 and later dual cat 4 O2 sensor systems come as a unit with both cats for about $500.

Bluesman

MyBigToy · January 10, 2004

I agree with Jayman.

I've got a 1992 Grand Caravan with the 3.3 L that I purchased new, it's got 185K and the converter still works fine. It passes the smog test with flying colors, with less than half of the allowed particulates on any of the tests.

I do my own maintenance on the van. Plugs - every 50K, wires - at 90K & 175K, oil/filter changes - every 3-4K, O2 at 90K, transmission fluid/filter changes (I let the shop do this messy job!) - 30K.

I'm still on the original tranny and they were prone to problems. I'm a believer in the fluid/filter changes for the tranny now. I'm able to get this done for less than $40 if I watch the newspaper coupons. I'm probably going to go to the full system flush on my Avalanche, you only change about 1/3 of the fluid with pan-drops.

MBT

JayMan · January 10, 2004

I guy I know bought a '93 Caravan and was so cheap he squeaked: oil changes every year or two using the no-name cheapest oil he could find, never opened the hood, etc.

At 75,000 hard miles, the tranny started to slip, The thing also left a smoke trail behind from the ruined motor. Believe it or not, this cheap b****** had the thing towed to the local Dodge dealer and made them do the tranny FOR FREE as part of that recall campaign.

They agreed too. See, this dude is a lawyer. Ever notice that lawyers, doctors, accountants, and dentists as a group have a genetic defect that prevents them from caring for their cars??

Of course, they can pass the "savings" on to us.

When you figure the cost of a new or rebuilt 4L60E, it's WAY cheaper to do a flush/fill or even just a pan drop every year using a synthetic ATF. It will take over 20 years to get close to the cost of the tranny.

I agree that O2 sensors are maintenance items. I would never buy from a stealer, as the aftermarket stuff has to meet EPA standards. I've had good luck with Neihoff from NAPA, and they're a fraction of the cost of the stealer. Only a few companies make O2 sensors, and I've noticed the Neihoff I've used in the past are genuine Bosch Made In Germany.

So I guess us "normal" folks have to look after our equipment and stretch every penny.

LS1Steve · January 11, 2004

i'm in california and technically can't change mine until they go bad or have been on for some long period of time, so i took a sledge to them and made it seem like they were "damaged" while offroading so i could replace them, just in case anyone gave me grief

JayMan · January 12, 2004

Ya gotta do what ya gotta do!

AZ-Z71 · January 12, 2004

Yeah, 98,000 and one of mine is bad. Unfortunately I can't just get one and you have to buy the two as one large "Y" pipe. Cost is about right at $500. Waiting to get mine converted over to true duals. I got a lot going on this month so it looks like beginin of next month until I get this all done. Grand total when I'm done will be around $900 with the new exhaust system. A lot of money for the cats at $500. Treat them right!