A catalytic converter that is working right gets pretty darn hot, and the ceramic substrate will hold the heat for a while. In my experience with a plugged catalytic converter, the engine would start and idle more or less normally, but the engine absolutely would not rev up to any RPMs and was way down on power. The car would not attain highway speeds and the engine got hot when I tried to go fast at all. When I decided it was a plugged converter, I unbolted the converter from the exhaust system and then tried to run water through it. The flow through the converter was almost nothing when I filled the intake end with my garden hose, and I wondered how the car had run at all. I "improved" the flow through the converter with a large screwdriver that I poked through the ceramic inside, and almost all the ceramic ended up falling out. Then I bolted the empty case back into place in the exhaust system and drove the car another 2 years. It picked up several miles per gallon gas mileage and would rev freely.
However I live in an area where so far we do not have to have our vehicles tested for emissions. I would not have dared to remove the guts from my catalytic converter if I thought it would have to be examined, since the case became nothing more than a large tube. We were really bucks down in those days, too.
Your 91 GMC probably has throttle body fuel injection. After all those miles, the injectors may be worn out. Or you may have a vacuum leak somewhere that is leaning out a cylinder or two. Do you get any trouble codes? It might pay to have the problem analyzed professionally. I sure would not advise removing the converter and/or destroying it unless a plugged converter is what the experts come up with.
By the way, 240K miles is kind of amazing. You must be doing something right...most folks get lots less before they have to put an engine in almost any gas pickup. Good luck!
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]
Today's Featured Article - Talk of the Town: How to Remove a Broken Bolt - by Staff. Another neat discussion from the Tractor Talk Discussion Forum. The discussion started out with the following post: "I have an aluminum steering gear housing with a bolt broken off in it. The bolt is about a 3/8" x 1 1/2" bolt. I've already drilled the center of the bolt out with about 7/64" drill bit the entire length of the bolt. Only one end of the bolt is visible. I tried to use an easy out but it wasn't budging and I didn't want t
... [Read Article]
Latest Ad:
2022 John Deere 5045E, 4wd, front end loader and 3rd function with grapple. 120 hrs, 55k new, must sell
[More Ads]
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy
TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
