Anyway to confirm its the precat other than going to a shop and having them take it out? I used one of those laser thermometers, a long time ago, and found that the temp after the bank 1 precat was hotter than before the precat. Based on some videos, that indicates a bad precat because it should be the other way around. Is that accurate? Thanks !!

 

 

Thanks, ill look more into this.

 

Im thinking of trying to change the rear precat myself, only hand tools. Do I remove the y pipe then the 2 bolts on the precat? if so, any tips on removing and reinstalling ypipe and new precat? Thanks!

 

Just now reading your post. You have to take the intake manifold off, also the wiper cowl (x2). I'm still in the process on doing this its a pain in the ***. I suggest soaking the nuts and bolts with penetrating oil for a few days. The ypipe can actually stay on, the heat shield bolts are 10mm, the precat and ypipe bolts are 14mm, make sure you have a decent size extension and breaker bar. Also you may wanna think about getter a MAPP gas torch to heat of nuts and bolts.

 

correct me if im wrong, please. instead of removing the ypipe, you unbolted the precat from the ypipe, leaving the ypipe as is. Then you took off the intake manifold. Does the manifold with the precat slide out? or did you have to remove. I would greatly appreciate the steps you took. This would be my first time working on this. Would like to see if its possible doing myself over paying $480 parts & labor. Thanks again!

 

Take the intake manifold off first, then the two cowls that are under you wipers. The ypipe can stay. I would start with disconnecting the upstream o2 from the harness (one on top), spray penetrating oil on the heat shield bolts, ones you have the heat shield bolts off, spray more penetrating oil on the two top 14mm nuts, break the two top nuts loose, don't remove them all the way just yet. Now soak the ypipe to lower precat bolts with penetrating oil along with the two lower precat bolts (You have to look up at the exhaust manifold to see them). Remove the lower precat bolts (I drilled the head off...), remove, disconnect downstream o2 from harness, remove lower precat bolts. Now you can remove the top nuts.

 

thank you for this detailed writeup. I might give this a try. Still debating whether to buy a CARB compliant precat ($230+ on rockauto) or paying a shop. Best quote ive gotten is $480 w/ 50k warranty.

 

Due to lack of power tools and such, I ended up having a shop do this shortly after. I soon have to change the front pre cat. Do you have any experience in changing that one? I would like to assume it "shouldn't" be as difficult. I'm curious if it can be done without removing other parts such as the radiator fans/shroud. But if I have to remove them to make room, I can attempt to do both by replacing my radiator at the same time. I have a leak or two at the very top part of the radiator. Thanks!