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Discussion Starter · #1 ·
I originally posted this on the 700 section.<p>Has anyone used the lower priced Volvo replacement cat conv (8551976-7) on a car ( mine is a 91 745)? I replaced mine and the core melted and was replaced on warranty after less than a year. Now the second one has clogged up! <br>I believe the problem is with the quality of the reduced price replacement and wanted to find out if anyone used them with or with out problems. <br> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0">
 

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Re: Cat. Life (VolvoBob)

Bob,<p>It's most likely that you have a problem with how the cat was installed or an engine management problem -- not a problem with the converter itself. The more expensive catalytic converter is constructed using higher quality stainless steel and greater quantities of catalytic metal (platinum, rhodium, palladium). The ceramic substrate is essentially the same.<p>A melted substrate suggests that the converter operated well in excess of its design limit. This occurs when the exhaust contains more pollutants than would normally be the case -- typically, higher hydrocarbons. Chances are that the more expensive cat would have melted just as quickly, as the dropping point of ceramic is far greater than any of the catalytic metals that were listed.<p>Did you buy/fit a new OEM (i.e. Bosch of OE Volvo) heated O2 sensor. Did you use new gaskets? How about the flange -- the available Volvo cats have a slightly different flange that sometimes makes it difficult to get a good seal -- a proper stainless steel flange frequently needs to be welded on. Otherwise, there's an air leak that the O2 sensor interprets as a lean charge -- increasing the injector flow rate to compensate. The result -- rich operating condition and overheated cat.<p>Alternatively, the cause of the original cat's failure was probably related to an engine management fault -- either a bad MAF, heated O2 sensor, bad wiring, or a bad ECU. Why did you replace the original cat? Was your repair prompted by a failed emissions test? If so, that should have been the mechanic's first hint of an underlying engine management fault (not to mention a variety of fault codes stored in the ECU's memory).<p>Any mechanic worth his/her salt should have investigated the cause of the original cat melt-down. This isn't rocket science.
 

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Re: Cat. Life (RearWheelPaul)

Paul:<p>The car recently passed the state polution test with no problems!<br>I'm not asking for a diagnosis of any problem here, just asking if anyone used one of these cats (or even a similar one on another year/model) and if they had any problems or not.
 

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Re: Cat. Life (VolvoBob)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>VolvoBob</b> »</i></TD></TR><TR><TD CLASS="quote">just asking if anyone used one of these cats (or even a similar one on another year/model) and if they had any problems or not.</TD></TR></TABLE><p>Yes. No problem.
 

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Re: Cat. Life (RearWheelPaul)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>RearWheelPaul</b> »</i></TD></TR><TR><TD CLASS="quote"><p>Yes. No problem.</TD></TR></TABLE><p>I am with you Paul. He either has one of two problems. His car is not running right weather it passed NY state test or not is beside the point. Or the cat is wrong one for the car. Hint here NYC guy FLOW rates are NOT all the same. A melted cat is just that, and cause from that. Something is wrong weather he likes it or not. A rusted out cat or cracked case is one thing if he was going for the CHEAP is crap idea or suggestion. But melted ceramic internals is just plain not the case. Unless he has the first and only rare correct size/flow and melted one, more or less not a cause form CHEAP. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/sly.gif" BORDER="0">
 

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Re: Cat. Life (VolvoBob)

~$300 for a catalytic converter is cheap. An OEM quality cat for a Volvo (or from Volvo) costs ~$800.<p>Regardless, even the $300 cat won't melt provided that the engine is running within normal parameters.
 

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Discussion Starter · #8 ·
Re: Cat. Life (RearWheelPaul)

Paul:<p>Now your getting to my whole point in this thread. If the CAT I bought from VOLVO is not good enough for my car why are they selling it <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0">
 

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Re: Cat. Life (VolvoBob)

Bob,<p> I'd suggest re-reading Paul's first post. The catalytic converter is a 'passive' component; it can react to events, but it cannot change them. My 1970 has a great big opening for the service station to deliver fuel to my tank; yours is itty-bitty by comparison.<p> This isn't coincidence.<p> Back in the days (late 1970's & early 1980's) when most cars used gasoline -- with tetraethyl lead added -- as fuel, and some cars used that newfangled 'un-leaded', it was VITAL that there could be no way a clueless pump jockey could put the wrong gas in your car.<p> Why? Easy. Lead wrecks your cat. Too much blow-by (say, sloppy rings)? Bye-bye cat.<p> If you look at the owners' manuals for late 1970's cars equipped with cats, they'll usually caution you about prolonged idling or excessive pumping of the gas pedal with the engine off (we're assuning a carbureted car, here). Why? Loads up the cat with unburned gas... once more, bye-bye cat, and, in this last example, the rest of the car with it.<p> If everything upstream of the cat isn't working right, having the best cat in the universe won't help. By the same token, if everything else is OK, using the cheapest certified cat you can find is also OK, since all legitimate makers have to pass a government certification.<p> Hoping you find this useful,<p> -Chris.
 

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Re: Cat. Life (VolvoBob)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>VolvoBob</b> »</i></TD></TR><TR><TD CLASS="quote">Paul:<p>Now your getting to my whole point in this thread. If the CAT I bought from VOLVO is not good enough for my car why are they selling it <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0"> </TD></TR></TABLE><p>Your point was taken and saw. But you are not getting and understanding what is being said BACK to you by MANY of us. Your car has a running problem. NO cat can correct that and that is it. The fact that a SECOND cheap cat has failed is past the point of this whole thing and has NOTHING to do with or little at all with your above statement. A cheaper cat MIGHT fail faster on a screwed up car thou. You got one and need to see that. AS a EXPENSIVE cat will fail as well in time and then you will see the fact and have spent too much of your and our time on coulda shoulda woulda of a bad running car. Reread my first post and that will answer why VOLVO sells a $300 cat and a $800 cat thou. Again you have a far differnt problem then you wish to realize/accept. And will keep taking the easy (answer) way out (cheap cat is junk ideal) over and over till you realize this. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/rolleyes.gif" BORDER="0"> <BR><BR>
<i>Modified by Nato740 at 5:24 PM 6-30-2006</i>
 

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Re: Cat. Life (VolvoBob)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>VolvoBob</b> »</i></TD></TR><TR><TD CLASS="quote">Paul:<p>Now your getting to my whole point in this thread. If the CAT I bought from VOLVO is not good enough for my car why are they selling it <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0"> </TD></TR></TABLE><p>You were given the choice of purchasing the OE quality converter for $800 or the cheaper unit for ~$300. The choice was yours.<p>Converter quality is a function of two things: The metal used for the outer case and the quantity of the precious metals used to coat the ceramic substrate. The ceramic substrate is essentially the same. <p>Look up the price of platinum and palladium on the metals exchange and you'll understand what my explanation of the price differential, as these metals trade at over $300/ounce. <p>Regardless, your catalyst temps must be right through the roof if the substrate is melted. Ceramic decomposes at temperatures above 2000C, whereas palladium and platinum melt at 1555 and 1773C respectively.<p>You have an engine management problem -- not a cat problem, Bob. <p> <p>
 

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Re: Cat. Life (RearWheelPaul)

Thanks Paul for that post. I was going to go there as well, but thought he would STILL not get it so I did not. Glad you took the time and posted that. Thou I still think it will go on Deaf ears. But then again.... <IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0">
 

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Re: Cat. Life (Nato740)

Having gone over the fundametals for Bob (sigh)... I'm curious; all my cars from my first (a beloved '66 Olds) to my current (a pretty d-d cool '70 144s) used to run on regular, so what I know about cats comes from life before unleaded, being a former shop helper, and mostly observing my best friend's tribulations (he's an ASE-certified mechanic).<p> The object of my curiosity: in what case might a cat fail that *didn't* involve something upstream of it? Other than something preventing ambient cooling of the cat, I can't imagine anything that could. Ideas?
 

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Re: Cat. Life (Alaric)

From the Bosch Automotive Handbook:<p>"As the maximum operating temperature [of a catalytic converter] is reached just slightly above 1000 C, the units are generally installed at a less critical location under the floor of the vehicle. Engine malfuntions, such as ignition miss, can cause the temperature in the catalytic converter to increase to the point where the substrate melts, resulting in the destruction of the unit."<p>- 3rd Edition, page 481.<br>
 

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Re: Cat. Life (Alaric)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Alaric</b> »</i></TD></TR><TR><TD CLASS="quote"> Having gone over the fundametals for Bob (sigh)... I'm curious; all my cars from my first (a beloved '66 Olds) to my current (a pretty d-d cool '70 144s) used to run on regular, so what I know about cats comes from life before unleaded, being a former shop helper, and mostly observing my best friend's tribulations (he's an ASE-certified mechanic).<p> The object of my curiosity: in what case might a cat fail that *didn't* involve something upstream of it? Other than something preventing ambient cooling of the cat, I can't imagine anything that could. Ideas?</TD></TR></TABLE><p>Good question, easy answer too. If a car has a cat failure (and this tends to need a explaination as to JUST what you term failure) it comes from one of three things. <p>1) it melts hense a badley running car with as we all have told him engine related cause.<p>2) rusted out caseing/flange welds. That is self explaination. Just cheap sheet metal not stainless or coated anti rust type case or pipes.<p>3) Over heat (melted) from downstream blockage. This is a badley bent/crushed (from an accident) pipe that is not flowing right or a blocked muffler. Hense exhaust backup and furnace like temps. This has not been told nor owned up to as the case to us by the poster. So we excluded them. But again lack of power would be a sure sign to him in the first place not a melted cat in the second place. <p>Air comes in mixes with gas and goes BOOM and has to get out. Basic Law of Physics. Not advanced rocket science <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/rolleyes.gif" BORDER="0">
 

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Re: Cat. Life (Nato740)

Thanks for satisfyting my curiosity, Rich.<p> As an additional note to Bob, I discovered the following link (<A HREF="http://www.epa.gov/OTAQ/cert/factshts/catcvrts.pdf" TARGET="_blank">http://www.epa.gov/OTAQ/cert/factshts/catcvrts.pdf</A>) through eBay, of all places.<p> This links to a document issued by the EPA's Office of Air and Radiation, and is entitled "What You Should Know about Using, Installing, or Buying Aftermarket Catalytic Converters". Among other things, it spells out warranties and remedies.<p> For a government document, it's actually pretty readable, and has a fair bit of useful information, both legal and techical.<p> Regards,<p> -Chris.
 
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