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  • Catalytic Converter Upgrade - 240

My 1992 240 has close to 430,000km on it so I'm wondering if it's likely that the catalytic converter has seen better days.
However, the car makes reasonable power and has good fuel economy.

Is it likely that I would see a difference by replacing the cat?

Is it worthwhile only replacing the cat, or does the while exhaust need to be replaced to make any difference?
240;7885 wroteMy 1992 240 has close to 430,000km

Is it likely that I would see a difference by replacing the cat?
At that mileage, the short answer is 'Yes', but that's more of a 'probably' than a 'definitely & unequivocally'.

Cat converters don't last forever and can & do plug up/melt/break apart internally and start rattling/etc...

If you're able to actually drop the exhaust and visually inspect it you'll be able to easily tell if it's stuffed or not.

How is the rest of the engine though? Ignition components/injectors/sensors/compression... If the cat is close to the last thing on a list of Old Worn-Out Stuff To Replace, probably not too bad an idea to get it changed.
240;7885 wrotethe car makes reasonable power
No it doesn't.
I've been wondering about the cat on mine too. (Newest car I've owned was built 1981. So I've never owned a car with a catalytic converter.) Mainly due to having no idea of the expense.

i.e. Early 240s don't have one. So is there any reason we can't just omit it when the time comes - and replace it with straight pipe? Apart from the added pollution I mean. Because I figure if I were still driving my '78 244, it wouldn't have one.
Around $200 from an exhaust shop. Nothing fancy is needed. Cheaper ones that barely convert anything are less, but more for performance applications.

It's illegal to remove your cat on a car fitted with one. No exhaust shop with a licence will do it. A catalytic converter combines oxygen with carbon monoxide (CO) and unburned hydrocarbons (HC) to produce carbon dioxide (CO2) and water (H2O) and reduce oxides of nitrogen (NOx).

So you are harming the environment on a dead stock car that has no gain by removing the unit. Though țhey do collapse and you may not have any honeycomb left in there right now.
Yes Vee Que is right, it is illegal to remove it, and if by some chance you were pulled over by a police officer who wanted to look over a Volvo, your car would probably get defected.
Also - LH2.4 uses an oxygen sensor as part of the engine management system, which would be missing if you removed the cat, I think.

So I've had "they do collapse" and "if it ain't broke don't fix it"... I'm still not sure which way to go.
Is it easy to replace yourself or best done by an exhaust shop?

And while I'm thinking about exhaust - is it worth putting decent extractors on an NA 240 or just pouring money away?
Disco_Inferno;125070 wroteNo it doesn't.
Good point... I should say that for a 240, it makes good power.
You need to weld them in for non genuine.
The original cat on my 940 broke up and started rattling in 2004 and about 260K km. Just for a laugh I asked a Volvo dealer for a price on a new one. $1500 + GST!
I went to an exhaust shop and they welded in a new one for around $200.
Vee_Que said the honeycomb collapses over time (which hints that we can't tell when it does) , and '240' said the O2 sensor would be affected if the cat was removed. So wouldn't both situations cause the O2 sensor to supply an incorrect reference voltage (affecting computer output and fueling), or neither would?
The o2 is before the cat, it means there will be less heat in that area because the cat is no longer restricting flow.
Hm, ok - thanks. I like to understand how things work.

So I'm guessing the reason cat converters are thicker than the exhaust pipe, is because they restrict exhaust flow to change the exhaust gas into safer components - thus they're larger to increase/balance that flow rate back up again (and if they were the same diameter exhaust back pressure would increase). So removing a cat might, what... increase exhaust flow and mpg slightly but not enough to bother about any gain - but what would the result be on the O2 sensor of that lower temp? No, wait - you said it would be cooler - so the sensor can't be at a lower temp if the flow is the same with or without the catcon - so what I've said above is wrong. Ah, nvm, LOL.
The purpose of a single upstream O2 sensor is to provide feedback to the engine computer so the correct fuel mixture is fed into the engine, to optimise performance and emissions. Removing the cat will not change this nor will it change the effectiveness of the O2 sensor. As stated, best bet if you are concerned is to drop the exhaust where the cat pipe connects and inspect the cat for blockage and damage. If none, then bolt back up again and good to go. I had excessive carbon buildup on the cat in my 240 with B21FT due to a leaky turbo seal, and it caused a lot of backpressure (enemy to a turbo!) When I bypassed the cat for testing purposes :) the performance gain was impressive. I have tried this on cars where there was no apparent damage to the cat and it had little to no perceived performance improvement - and I wouldn't recommend it due to the legal and ethical implications. :)
It's not worth doing on a stock non turbo car. Turbo car, fit a high flow cat yes.
Get a "CAT scan" done, then you will know for sure.
familyman;125398 wrote[Groan...]
Is that a muffled...or an exhausted "groan" ?
Ethical and environmental considerations are always in the back of our minds..... But a Volvo driven say 1-2000klms per year with the CAT deleted is really no environmental disaster? Yes, a Toyota with no CAT should be crushed because it's about as good as a faulty microwave.

As mentioned earlier earlier cars didn't have them so if your 80's or 90s Volvo's has a busted cat and you do next to no KLMS, just delete it.
I agree that the environmental impact of a single infrequently-driven car with busted cat is minimal, but you should still replace the cat if you can. I don't think it's okay to say don't worry about it, you'd probably still be unhappy with someone tossing a plastic wrapper on the ground, even though a single wrapper isn't an environmental disaster.

Besides, CO is way worse for you than CO2, and as the driver you'll inevitably breathe in some of it.
I appreciate the argument and in principle agree..... But as an example my old 122 and 142 clogs my lungs with all sorts of stuff (imperfect carby tuning, crankcase ventilation to the atmosphere and a firewall that doesn't seal the engine bay from the cabin like a modern car - ingesting the said crankcase ventilation etc etc), not to mention the environment (who remembers the cloud of Pooh over the city every day in the 80s?). By the same rationale we should all be retrofitting our pre 86 cars with CATs if they are used often?

Since the 122 and 142 only do a couple of thousand per year (combined) I accept she's poisoning me and the environment at "tolerable levels".... If my cat on a 240 failed I'd fix if it was a daily and delete if mostly a garage Queen / once a month car.

Perhaps the law would make more sense if all fully registered cars needed some form of CAT regardless of age and all limited use cars exempt?
That would make sense but the amount of non-cat cars on the road is dwindling and perhaps the government assumes that eventually they would cease to exist.
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