Hypothetical question here… 
say the cat was “springing” exhaust leaks from rusted connections and bolts in the bottom area of the cat…and assuming you were in a state without emissions requirements…would removing the converter and just putting a straight pipe in cause any engine (or other) problems? Other than the emissions bit of course…
Thanks in advance…
Jad
See Jad? When you start doing this kind of stuff, you turn into a HACK! A hack is person who takes something that they know nothing about, and try to make it last longer by taking short-cuts at everybody’s elses expense.
Soooo, you get nothin’ from me!
Tester
Ohhh come on Tester…I know you want to tell me…transform me from a hack into a shadetree… apprentice, or something like that…
P.S. It’s (hypothetically) a 1985 Oldsmobile Cutlass Supreme.
Pssst… Don’t tell ayone, but running with a straight pipe instead of the cat will not hurt the engine. Just the air we breathe. Keep it down, because it is also a Federal crime. Shhhh. Hush. Someone will hear.
If you have a 1976 Impala, you will cause no damage. If the car has a computer, you will change something like gas mileage or performance. Your pollution will go up to seven times more. At least. Fix the exhaust and your CO might not choke you to death.
Well, if it’s just the air we breathe then this might not be so hypothetical in the end!! Haha…federal crime eh? Uh oh…
It won’t hurt the engine at all. I don’t know that a missing converter is any worse than someone driving around in a late model car for 3 years with the CEL on due to an inoperative EGR system and perfectly good converters!
Just funnin’ (Okie slang) here a bit.
If your '85 Olds is like every other '85 Olds I’ve ever seen, all of the other emissions equipment has long since died or been removed, and the carb is wildly out of tune, so cutting or gutting the cats isn’t going to hurt much.
As ok4450 said, you’re certainly not the worst offender, and it’s hard to single out a guy when there are people who live with the, “Well, gee, that light’s been on for 6 months, but it seems to run fine” creed. If you’re looking for any more justification, just think about the resources that have to go in to building a brand new car; surely driving the same car for 23 years is at least somewhat more responsible than buying 2 or 3 new ones in that time.
It’s a nice car why butcher it? When I replaced one part of an exhaust on an older car, a few weeks later another part went bad, sometimes it’s cheaper (laborwise) and easier to replace the entire exhaust system in one shot.
Ed B.
Thanks everyone for your replies, especially the humorous ones…
On a side note, I’ve noticed a strong smell from the car when it sits overnight or longer…I’m leaning towards a fuel smell, but it’s not a straight “I’m at a gas station” smell…maybe it’s mixed in with other stuff in the engine compartment, not sure. No leaks on the floor. The smell is getting into the house so my wife has forced me to park it outside in this cold! Would like to find out the source, but not sure how. It runs the same as before and I don’t notice a difference in fuel consumption. Any ideas? Could it be a clogged vapor canistor?
Thanks Ed, I might run new pipe all the way down and see how the muffler looks if/when I do this.
An hypothetical automobile with a feedback carburator which is still functioning safely and reliably will operate without a catalytic converter.
The feedback system will usually fail in such a manner, however, to cause the engine to run with the MC solenoid open, i.e., full rich. Fuel mileage will be near or below 10 mpg, power will be severely limited, and plugs will foul in a few hundred miles. Retrofitting such a car to pre-1980 specs will make it driveable but is it worth the expense, hypothetically, of course?
It’s time for your trusted 22 year old to move on.
Yeah, it could be a saturated charcoal bed. It’s a possibility. It’s also a possibility that you have a cracked and leaking fuel line fitting. Or a rusted and leaking gas tank. Or a leakiing injector body.
So, you’re blowing exhaust through the holes in the canister that was once your catalytic converter, you’re ventilating gas into the air…is there more we should know?
I would love a 2007 Dodge Charger but unfortunately don’t have the funds for one yet…gotta make this 'ol girl last a bit longer.
Would a good mechanic be able to track down such leaks or diagnose a saturated charcoal bed?
The cat will be fixed or just bypassed…the geniuses behind our emissions testing here have decided that 20+ year old vehicles are exempt from emissions testing…I don’t really get that reasoning (can someone explain that to me?) but if it’s clean enough for them, it’s clean enough for me.
I don’t see how removing the converter will cause the feedback system to fail…?
Yup, a good mechanic can do this.
It really makes no sense to be testing cars over 20 years old IMHO. You can’t make a vehicle designed 20 years ago comply with modern standards, and there aren’t enough of them out there to have any significant impact. In NH it even becomes an official antique at 25. Actually, in NH emissions testing has been replaced with OBDII downloading, and anything earlier than 1996 didn;t even have to have an OBDII system.
I guess I see your points, but it just seems to me that these older cars would be the ones making the worst “contribution”, emissions-wise…not that I’m complaining!
Yup, the average american changes cars about every ten minutes and junks them at the first major repair. There just aren’t enough old cars out there to be a significant contribution, so it’s not cost effective to worry about testing them. If the car was a few years older, it wouldn’t have a catalytic converter anyway.
JC Whiteny lists one for this car for $55.99. I’d put the CAT back on and not try to bypass anything. The pollution you cause is one problem . . . the federal law you break is another . . . and finally the car was designed to run with a CAT and something will screw up on you (MPG, performance, whatever) causing you to come back here and asking “Why did my MPG drop?” or “Why is the car sluggish?” or “Why is the idle so rough?” and all because you tried to save a few dollars. I believe that everyone here who has turned a wrench has tried a shortcut or two, and lived to curse the day that they took that shortcut. I have, and shortcuts end up being the long way. Rocketman
These old feedback cars need the backpressure from the catalytic convertor. You can run one just fine without a muffler, but without that huge old convertor you’ll get very bad backfiring and possibly poor low-end performance. Now, if you really wanted to you could put a small-diameter muffler in the place of the convertor and it’d work fine, but if you’d have to buy a new muffler, you might as well spend the extra couple a’ bucks to buy that convertor Rocketman was talking about so you don’t choke us all and you don’t have to worry about those jackboots from the EPA busting down your door.