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Any tips on removing the front cats? I'm trying to replace my driver side cat and, while I was able to get all of the nuts off, I was not actually able to get the pipe free. I removed the shield over the mid-pipes, even removed what looked like screws holding the mid-pipe to the heat shielding (which I think was attached to the body above the mid-pipes) to try and get the mid-pipe to move enough, but I just couldn't get enough clearance to get the cat pipe off where it cups over the front of the mid-pipe. I was doing this with just the front of the car up on race ramps so getting to the rear exhaust was difficult. Since I was running out of daylight so I put everything back together for now. At least the bolts are loosened.
Any pro tips on this? I think I probably just needed around 1/4 of an inch more clearance to get the cat out. There's not a lot of room to move it around on the header side, so I'm guessing that loosening up the mid-pipes is the way to go, though I did read about loosening or dropping the header, but that seemed like a giant pain in the pipes...
It's been a few years since I've had that connection apart but my guess is the passenger side manifold/cat is preventing your X pipe from moving rearward enough to get driver's side cat out. Probably just have to loosen the pass side cat to x connection and it will give the wiggle you need. Be careful not to mash the donut gaskets.
I dont plan to removing my xpipe but definitely plan on removing the under pan and letting it hang down as far as it will go while protecting the bumper at the tips.
I will be working on replacing mine in a few weeks.
You need to disconnect the pass side from the x pipe, also makes it easier if you remove the X pipe hanger (two bolts towards the rear) to let the x pipe hang down. The driver side is the easier of the two to get out, but you will need to remove a couple of the studs (unless you plan on unbolting the engine mount and raising the engine). They are a pain to remove but doable. A 7mm socket fits them.
Thanks all. I thought I removed the x pipe hangar, but I removed 3 screws on each side. Maybe that was only removing the x pipe from the heat shield and missed the hangar. With the car on the ramps I couldn't get far enough under to really see what was going on that far back.
I didn't try removing the passenger side cat bolts... that would have been smart
Thanks for the tips! I will try again this weekend.
I got my old cat off (pulling the studs was the key for me) but I cannot get the new one to fit properly. When it is flush to the manifold, it's about 1/2 inch away from meeting the xpipe and aobut 1/2 inch higher than the xpipe. I loosened the passenger-side cat so the xpipe movement wasn't so restricted, but I did not undo the xpipe hangar because the problem was that the xpipe was lower than the cat. I jacked up the xpipe and managed to get the cat and xpipe connected, but it's just not a good seal and it's leaking quite badly right now.
I'm not sure what to do at this point. It seems the new cat has a slightly different shape than the old one. I'm not sure if this is an actual problem with my cat, or if this is within expected tolerances for exhaust systems.
Any pointers? After a good 8 hours spent messing with this across two days, I'm tempted to just say screw it and take it somewhere to get a performance exhaust put in while getting this fixed, but it seems I don't have much of an option right now except to put my old cat back in. This has been way more of a pain than replacing my fuel injectors was.
if you still have the other factory cat on the car it may be pushing the xpipe back. Remove the other cat and put both aftermarket pipes on. Then loosen the clamps that connect the rear axle back to the xpipe as well as the two bolt from the xpipe hanger. That will give you some play with the xpipe front to rear. Tighten up the xpipe to the down pipes, tighten the clamps on the axle back, reinstall the xpipe hanger.
Originally Posted by Nelno
I got my old cat off (pulling the studs was the key for me) but I cannot get the new one to fit properly. When it is flush to the manifold, it's about 1/2 inch away from meeting the xpipe and aobut 1/2 inch higher than the xpipe. I loosened the passenger-side cat so the xpipe movement wasn't so restricted, but I did not undo the xpipe hangar because the problem was that the xpipe was lower than the cat. I jacked up the xpipe and managed to get the cat and xpipe connected, but it's just not a good seal and it's leaking quite badly right now.
I'm not sure what to do at this point. It seems the new cat has a slightly different shape than the old one. I'm not sure if this is an actual problem with my cat, or if this is within expected tolerances for exhaust systems.
Any pointers? After a good 8 hours spent messing with this across two days, I'm tempted to just say screw it and take it somewhere to get a performance exhaust put in while getting this fixed, but it seems I don't have much of an option right now except to put my old cat back in. This has been way more of a pain than replacing my fuel injectors was.
Thanks. I did loosen the other factory cat, but not the xpipe-to-axel back connections, because I was trying to do this using just my race ramps without putting the whole thing on 4 jack stands. It seems clear that was a mistake because I couldn't get to the axel back that way.
What I have now is a factory cat on the passenger side, an OEM (GM) cat on the driver side. These seem significantly different in length and curvature.
I'm about to do a leak test on the whole thing with it on 4 jack stands. I am sure it's leaking at the driver-side cat-to-xpipe connector, but it was so difficult to get the cat + gasket + studs back on the manifold that I'm not confident that is entirely flush, either.
Sounds like I really just need to loosen everything up and and get it all connected before tightening everything down by rotating through all the bolts a bit at a time. I'm still worried that this difference in the length of the new cat, despite being an OEM part, is just too much for everything get back together again without any leaks.
Turn's out it wasn't leaking where the new (driver-side) cat and xpipe joined, but where the old (passenger-side) cat and xpipe joined because I hadn't fully tightened down the flange. When I was working on it last time it was getting dark and I needed to move the vehicle so I was in a hurry to get it back together, assuming I would have to put it up again to redo the new cat, anyway. I'm glad I did the test or I'd have taken everything apart again. Seems to be good now. Thanks for the tips!
Removing the drivers side cat on my c7 z51. Did you remove the o2 sensors first from the cat or did you just disconnect them from the plug in area in the trans tunnel? It’s super tight up in there!
I'm doing my driver side now. How did you get the nut loose thats right above the rear lower swing arm mount. The angle is horrible and I cannot seem to get a mix of sockets or wrenches in there. This is the only thing holding me up at the moment.
Thanks,
Nic
I know I am late to the game , but the way I did it was to loosen the motor mount bolts on each side and jack the engine up enough to get the pipe out. Also I remove the mid pipe to the axle-back. It worked well for me.
Front Cat Removal
