Several converters would work on Blazer

Hey there, time traveller!
This article was published 02/10/2009 (5942 days ago), so information in it may no longer be current.

QUESTION: I have a 2003 Chevrolet Blazer. I have been told that the irritating rattling noise that I hear from under the Blazer just means I need a new catalytic converter. It doesn’t hurt the operation of the vehicle, only the emission side of things.

My question is, does the replacement catalytic converter have to come from another Chev Blazer? The reason I ask is because I’m told that muffler shops/garages usually cut the muffler pipe on each end of the converter and just weld on the new one. This would leave me to believe I can use a converter from other vehicles. I look forward to your reply.

ANSWER: Catalytic converters may be bolted in on some vehicles, welded in on others. Some use a combination — bolted at one end and welded at the other. Regardless of the installation method, there are a few things to watch for when replacing a catalytic converter.

First, you would be looking for a three-way converter rather than a two-way converter. The three- and two-way refers to the gases that are converted. A three-way unit converts hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx). The two-way units only convert HC and CO. The emissions label under the hood states what type of converter is on that vehicle.

Next, you need a converter that has similar oxygen storage capacity as your original unit. This means the size and type of material inside the converter must be similar. On vehicles built after 1996, efficiency of catalytic converters is monitored by oxygen sensors mounted before and after the converter. If you have a unit with different capacity, then the fuel-injection computer may set codes occasionally indicating a bad catalytic converter.

Now that you know what to watch out for, there are probably several converters from different vehicles that would work on your Blazer. Look for one from a GM vehicle, as different manufacturers vary in their composition slightly. Also, select one for a vehicle with the same size engine and type of fuel-injection system. For example, one from a van or pickup would likely work fine if the engine was the same.

If selecting a used converter, make sure it doesn’t rattle, and look in the ends to see if the fine passages are plugged with carbon or oil. A plugged converter will lower performance and increase fuel use.

 

QUESTION: I have a 2003 Nissan Altima V-6 with 220,000 km. It has been a great car with very few problems (actually for a period of time we had two Nissan Altimas) until approximately one year ago when the engine started burning oil. I contacted the local garage (not a dealer) and they advised that a number of clients with Nissan Altimas were having the same problem.

Since a small local garage has been having Nissan customers complain, I am sure that this would be the same situation across Canada. Have you heard of this situation with the Nissan Altima and is Nissan standing behind the problem? Any feedback would be greatly appreciated.

ANSWER: There have been several complaints about oil consumption with the 2002/2003 Altima on the Internet, but there is not a lot of documented information on the problem. Many of the complaints have been from owners of high-mileage vehicles, which would lead me to believe that the oil consumption may be caused by piston-ring wear.

Back in the 1970s, it was common for Nissan vehicles and many other imports to start using oil about 80,000 km. Nissan used a hard engine-block material and soft piston rings. The rings simply became worn at that mileage and needed replacement. Install new rings and the problem was fixed.

Today, vehicles continue to run with little maintenance and the thought of having major engine work done is unfathomable. Before condemning the rings however, have the PCV (positive crankcase ventilation) system checked, as a bad PCV valve can suck oil into the intake manifold.

By removing the sparkplugs and shining a light into the engine cylinders, you can see the piston tops. If the edges of the pistons are clean of carbon, this indicates oil coming past the rings and they need replacing. The rings may be worn, or if driven with the engine pinging could be broken. In either situation you need some engine work.

Jim Kerr is an experienced mechanic, instructor and member of the Automobile Journalists’ Association of Canada. kerr.jim@sasktel.net