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Date:         Sat, 15 Jan 2011 21:42:44 -0500
Reply-To:     Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject:      Re: Expected Life of a Cat Converter??
Comments: To: mcneely4@COX.NET
In-Reply-To:  <20110115184300.CKU3B.63446.imail@eastrmwml38>
Content-Type: text/plain; charset="utf-8"

What you say is true. In a perfect world the catalyst should last a real good long time. However there are many things that happen to reduce the life or otherwise reduce its efficiency. A Cat can fail to work without breaking up or becoming plugged. That is the main reason that the IM 240 dyno test was developed for emissions inspection. This load (dyno) test tests the cat and EGR systems for HC, CO, and Nox reduction. The NOX is only created when the engine is working. That is why the load test is needed.

Besides the obvious ignition or fuel management failures that can quickly kill a cat, there are a number of other factors that can reduce it life.

Incorrect ignition timing. This practice to increase power (ha) or response and smoothness, increases the production of NOx by increasing the peak flame temperatures. The higher exhaust temperatures can also have an impact.

Oil carryover is another problem. Excess oil level, wrong viscosity, worn valve guides/rings excessive high revs and engine braking all lead to some oil passing through to the exhaust. Anything that causes excessive blow by. This why oils have been reformulated with reduces ash and zinc compounds as those are bad for the Cat and O2 sensors.

What is really bad is that once a replacement Cat is needed most of go for aftermarket replacements. With few exceptions these units have less active material. Usually smaller elements. Either smaller diameter or reduce length. All these leads to reduce efficiency, life and also engine performance.

Cats that plug or break up are sure signs that abuse or malfunction is the cause. Normal failure goes unnoticed except for the failed emissions inspections.

Dennis

-----Original Message----- From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Dave Mcneely Sent: Saturday, January 15, 2011 6:43 PM To: vanagon@GERRY.VANAGON.COM Subject: Re: Expected Life of a Cat Converter??

I have never seen a factory recommendation for replacing the catalytic converter on any vehicle at some particular mileage. My understanding is that on a well maintained vehicle, they are supposed to last the life of the vehicle. Certainly the price would make it seem so. Of course, most of our vans have gone beyond the originally expected life of the vehicle. I have been told by supposed experts that catalytic converters only fail if there are other problems with the vehicle causing it to run poorly for an extended period of time (mainly running rich), or if contaminated fuel is used (such as leaded fuel in Latin America).

DMc

---- Tom Hargrave <thargrav@HIWAAY.NET> wrote: > They go until they fail and they fail in one of two ways, they plug up or > the catalyst gets contaminated. > > > Tom > www.towercooler.com > www.stir-plate.com > > > -----Original Message----- > From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of > John Rodgers > Sent: Saturday, January 15, 2011 3:55 PM > To: vanagon@GERRY.VANAGON.COM > Subject: Expected Life of a Cat Converter?? > > Anyone know the answer? > > Is the cat converter one of those things like an O2 sensor - to stay on > the game, it needs replacing every 60K, good or bad. Or - Do you just > run it until it gives trouble. > > I definitely believe in preventive maintenance, and I have 12 years on > my current cat since new- can't really say mileage. Over 130K, though. > The cats are pricey. > > What say "The List?" > > -- > John Rodgers > Clayartist and Moldmaker > 88'GL VW Bus Driver > Chelsea, AL > Http://www.moldhaus.com

-- David McNeely


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