YACT: How long do catalytic converters generally last?

[justint]

Mine seems to have gone out at 100,000 miles on a 98 Honda and they are $$$$ to replace.

 

[CraigRT]

$$? they are not that expensive.. and yeah, that sounds about average.. friend just got his replaced on a 97 Dakota 318cid at about 170,000 kms.. bought an aftermarket one. think it was only a buck 25 or something.

 

[justint]

The OEM ones are around $525 from hparts.com. I am kind of leary of putting aftermarket parts on my car.

 

[Zenmervolt]

They should last the life of the car. 217,000 miles on my old Accord and the cat was still good. A cat never just dies, it's always killed somehow. Either by leaded fuel, an overly-rich mixture, excessive heat, shutting the engine off at higher than idle speed, or other problems affecting exaust composition.

ZV

 

[NutBucket]

An aftermarket cat is not an issue. Just get something decent.

 

[Jzero]

Too bad the federally mandated warranty period is only 8 years/80k miles

 

[justint]

Originally posted by: NutBucket
An aftermarket cat is not an issue. Just get something decent.

Any suggestions for good sources/brands of atermarket cats for a Honda?

 

[squirrel dog]

I was going to say too rich a fuel mixture,but Zenmer covered that rather well.A cat can be killed in two or three weeks if your car is way out of tune,too rich fuel,ect.

 

[justint]

Originally posted by: squirrel dog
I was going to say too rich a fuel mixture,but Zenmer covered that rather well.A cat can be killed in two or three weeks if your car is way out of tune,too rich fuel,ect.

Well it wasn't leaded gas. Isn't the fuel mixture controller by the computer via measurements from the oxygen sensors? Wouldn't the sensors have been flagged as bad before anything happened to the cat?

 

[psteng19]

OEM replacements are about $100-200.
I got mine for $180 searching for online vendors on google.
Mine seemed to be more expensive than others for some reason ('95 Sentra), seeing that there were some in the low $100's.

 

[Zenmervolt]

Originally posted by: justint

Originally posted by: squirrel dog
I was going to say too rich a fuel mixture,but Zenmer covered that rather well.A cat can be killed in two or three weeks if your car is way out of tune,too rich fuel,ect.

Well it wasn't leaded gas. Isn't the fuel mixture controller by the computer via measurements from the oxygen sensors? Wouldn't the sensors have been flagged as bad before anything happened to the cat?

Sometimes an error code doesn't trigger the Check Engine MIL, and sometimes there's no sensor for what's wrong (burnt valves as an extreme example, bad plug(s) as a more common one). If there's un-burned fuel getting to the cat it can get clogged very quickly. Also, something could have caused an overheat condition in the exhaust without triggering a warning light, or you could have gotten bad gas at a station somewhere (not common, but definitely not unheard-of). I'd have then engine checked out just as a precaution. The cat might have just been marginal from the beginning (assembly line products tend to be that way, you might have gotten an outlier on the statistical distribution), but it's safest to make sure that nothing else is wrong because this could be a symptom of something worse.

ZV

 

[KokomoGST]

Originally posted by: justint

Originally posted by: squirrel dog
I was going to say too rich a fuel mixture,but Zenmer covered that rather well.A cat can be killed in two or three weeks if your car is way out of tune,too rich fuel,ect.

Well it wasn't leaded gas. Isn't the fuel mixture controller by the computer via measurements from the oxygen sensors? Wouldn't the sensors have been flagged as bad before anything happened to the cat?

Not if you're running something piggyback, have gigantic injectors, or throwing out counted air through the MAS/MAF...

There are a lot of people that vent their BOV on their DSMs that run pig rich because all that air the BOV vents was counted and supposed to remain in the closed loop of your car. iow, not to go back out to the atmosphere.

Your stock computer sometimes can't cope with too much fuel... like it's been said, tuning issue. Random makes high-flow cats for reasonable prices... they pass tailpipe tests fine. Be careful of those "test pipe"/non-baffled aftermarket cats... they prolly won't pass.

 

[rh71]

QUESTION: How do you know a catalytic converter is starting to go bad? We have a 90 Accord and the thing runs loud even when coasting. It's definitely coming from the underbody since I can almost feel the rumble. It only happens when going > 30mph. I doubt it's been a cold-weather thing since it was 40F degrees the other day and it still made the noise. The car is going on 110k miles and an oil change is also due.

 

[justint]

Originally posted by: rh71
QUESTION: How do you know a catalytic converter is starting to go bad? We have a 90 Accord and the thing runs loud even when coasting. It's definitely coming from the underbody since I can almost feel the rumble. It only happens when going > 30mph. I doubt it's been a cold-weather thing since it was 40F degrees the other day and it still made the noise. The car is going on 110k miles and an oil change is also due.

Check for a hole in the exhaust. You could also have a bad exhaust gasket. You should also check and see if the heat shield on the catalytic convertor is loose. That would cause a loud rattle not a rumble.

 

[NutBucket]

Rumble is most likely a hole in the exhaust. Dunno tho, you have a stainless steel exhaust. Maybe a stud broke or something. If anything, a broken cat will rattle. The inside of the cat is solid and if it breaks it will rattle. However, the cat will still work.

 

[justint]

Originally posted by: NutBucket
Rumble is most likely a hole in the exhaust. Dunno tho, you have a stainless steel exhaust. Maybe a stud broke or something. If anything, a broken cat will rattle. The inside of the cat is solid and if it breaks it will rattle. However, the cat will still work.

A good stainless steel exhaust should last forever right? His 90 Accord probably has a galvanized exhaust. At this point it is probably one massive corroded mess.

 

[rh71]

Originally posted by: justint

Originally posted by: NutBucket
Rumble is most likely a hole in the exhaust. Dunno tho, you have a stainless steel exhaust. Maybe a stud broke or something. If anything, a broken cat will rattle. The inside of the cat is solid and if it breaks it will rattle. However, the cat will still work.

A good stainless steel exhaust should last forever right? His 90 Accord probably has a galvanized exhaust. At this point it is probably one massive corroded mess.

Funny thing is we let my brother's gf's brother (who owns his own gas station) take a look at it. He saw nothing wrong nor heard anything wrong but the sound definitely wasn't THAT loud in recent years/winters. All he did after looking at it was tighten some screw on the exhaust... but the constant rumble (not rattle) is still there when coasting and accelerating. Don't you think he should've at least seen a hole if it's the exhaust/pipe ? Just curious... before I bring it in for an oil change and ask them to look at this problem too...

 

[NutBucket]

Originally posted by: justint

Originally posted by: NutBucket
Rumble is most likely a hole in the exhaust. Dunno tho, you have a stainless steel exhaust. Maybe a stud broke or something. If anything, a broken cat will rattle. The inside of the cat is solid and if it breaks it will rattle. However, the cat will still work.

A good stainless steel exhaust should last forever right? His 90 Accord probably has a galvanized exhaust. At this point it is probably one massive corroded mess.

That's just it, it is a stainless exhaust.

 

[amdskip]

They last until the car won't go anymore. We had a ford escort station wagon that we drove until it wouldn't move and just killed because the cat was bad.

 

[Analog]

so it fails, big deal. Unless your area requires emissions testing.