Replacing the Cat

[mxzeatr]

I have a 99 Silverado Ext Cab Z71. The check engine light is on, saying that the catalyst effiecency is below threshold on bank 2. So my question is, can I have one cat cut out, and another welded in, say an aftermarket one for like 80 bucks? Or should I replace the entire assembly (no welding needed) at about 300. I have been driving the truck for a while like this and its fine! But the SES light is bugging me....Thanks for any input!!!

[Bish]

I have a 99 Silverado Ext Cab Z71. The check engine light is on, saying that the catalyst effiecency is below threshold on bank 2. So my question is, can I have one cat cut out, and another welded in, say an aftermarket one for like 80 bucks? Or should I replace the entire assembly (no welding needed) at about 300. I have been driving the truck for a while like this and its fine! But the SES light is bugging me....Thanks for any input!!!

 

I see no reason you couldn't cut out the old and weld in a new. I went ahead and replaced the complete Y-pipe when one of mine went. I figured if one was going, the other wouldn't be too far behind. I also did o2 sensors (upstream only) at the same time as mine had over 100K on them. I think the Y pipe was around $250 IIRC.

[mxzeatr]

Thanks...How long did you wait to replace? Did you do it right when the light is on? I would rather replace the whole y-pipe, but I really don't have the money right now, if I can limp til April then for sure I will do it, I am planning on doing a diff. muffler set up as well....All of my O2 sensors are new...The truck has right around 140k on it....Thanks!

[Bish]

Thanks...How long did you wait to replace? Did you do it right when the light is on? I would rather replace the whole y-pipe, but I really don't have the money right now, if I can limp til April then for sure I will do it, I am planning on doing a diff. muffler set up as well....All of my O2 sensors are new...The truck has right around 140k on it....Thanks!

 

I replaced the Y-pipe because one of the cats had rusted to the point of buzzing constantly. It was still working as I did not have any SES light. Other than more pollutants out the tailpipe, I wouldn't worry about driving it. The front (pre cat) sensors handle air/fuel mix so it should run fine.

[mxzeatr]

Thanks for the info!

[Rolandd]

You may want to figure out why one cat failed if the other one is still substantially good. On ODBC-1 cars I remember people using a thermometer on the exhaust to measure how well the cat was working. You may want to have the other cat checked before springing for a new Y-pipe just to make sure you don't roach a new cat because of some other problem. If the truck has over 125,k the cat is probably tired and I would just change the Y-pipe because the other is likely not far behind.

[mxzeatr]

Ok, yea the truck has almost 140k on it, I figure it is just wore out. I am thinking about just waiting another little bit so I can start working and replace the entire Y, unless I start having troubles, then i will prolly just cut the cat out for about a month at max....Thanks for the info!