CaddieWampus

2006 CAYENNE 955 4.5 V8 DRIVER SIDE PRIMARY CAT REPLACEMENT Full size pictures can be found HERE Writing this down hoping it can help out another pepper owner. SKip to the bottom if you want the short version. Had to replace the drivers side (LHD) primary catalytic converter as the flex pipe had completely corroded away and was flopping loose in the wind. I got lucky and found an aftermarket one on eBay for significantly less than what the dealer would charge me. You’ll need an assortment of tools for the job: Jack Jack stands Ramps for rear 10mm sockets 12mm sockets 13mm sockets Numerous extensions Wrenches in above sizes and flex head ratcheting are awesome 22mm O2 sensor wrench or crowfoot Straight ⅜” and ¼” ratchets and breaker bars for extra leverage as needed. Flex head ⅜” ratchet Long flathead screwdriver to open up the clip holding the O2 sensor wire T25 screwdriver or bit for your screwgun for trim pieces #2 screwdriver or bit for your screwgun for trim pieces Total actual work time was about 8 hours. I could have done it in about 5 or even less if I was truly ambitious, but was taking my time and making sure I didn’t break anything in the tight space. The time also included jacking up the car, removing the underneath skid panels, engine compartment plastics, drivers tire and wheel well liner as well as reinstalling them. See Pelican Parts for the skinny on accomplishing all of those tasks. I’ll skip those tasks here. https://www.pelicanparts.com/techarticles/Porsche_Cayenne_Tech.htm Also crack open the rear hatch and block it from locking as you’ll want to disconnect the battery ground. Here is a video that shows how. Super easy and never knew myself. No need to flip the seat. How to disconnect battery ground in Porsche Cayenne (955) I will preface my replacement with the added bonus of the car having the secondary CAT delete already done. So no fighting with those. So under the car, first things first was loosening up the connection between the tailpipe section and the straight pipe, which was connected to the primary CAT. As the existing bolts on the CAT were rusted and frozen, I just snapped them off knowing they would be replaced anyways. Don’t waste your time on PB Blaster or heat. Just break them off and be done with it. So with the easy work complete now it’s time to dive into the fun part. Move up under the car so you’re looking straight up where the CAT meets the exhaust manifold. You’ve got 3 bolts above you that you’re wondering how you’ll ever get to them without taking out the front O2 sensor and even then how. Give them a spray of PB Blaster or your choice of penetrant. Now move to the front of the car in front of the sway bar, there is an opening where you can see the 3 nuts on the exhaust manifold. With a combination of extensions you can reach the nuts with a 12mm socket. You can let them soak for a little while as you have another cup of coffee or beverage of choice. At this point you may be wondering why I haven’t mentioned the O2 sensor on the top of the CAT pipe. Well, because I drove myself crazy trying to figure out how to get it out. I went after it 8 ways to Sunday. From the top with swivels and extensions and the same from underneath. I could barely get a finger over it and did manage to get the socket on it but then couldn’t get it broken free as the leverage just wasn’t there, or the socket/crowfoot slipped off. Needless to say, I wasted about an hour or so on this and questioned my seemingly foolish decision to approach this project. In the process of doing all of this, I figured out I needed to remove the middle skid plate support bracket for more room to reach up in the small area. Working by myself created new opportunities to be resourceful, or stupid depending on point of view. Since I was already committed to this endeavour by already removing, AKA breaking, the lower sections of exhaust piping, **** the torpedoes and full steam ahead. I ended up just unbolting the CAT from the exhaust manifold, dropping it down and slightly rotating it. At that point I had a good view of the O2 sensor and slipped the O2 sensor socket right over it with a breaker bar attachment. With the room to get leverage and a straight shot at it, it came loose with a marginal amount of effort. Unscrewed the sensor by hand and pushed it behind the steering column. Now for the next problem. The CAT was just big enough to not slide out with the heat shield of the steering column shaft in place. So, prop the CAT in place and remove the heat shield (2-10mm bolts), giving that extra ¾ of an inch. And so with a small amount of finagling, out she came. Could I have worked a little more on it and fought it out? Maybe. But for two 10mm bolts, easy choice. At this point in time, I called it for the day as I was now about 5 hours into the whole job. Sunday morning - here we go for part 2. Now knowing how it came out, it should make it easy to go back in. And yes, it was. Reverse the process of the removal. Slide the new slimmer CAT up into the general position it needs to be, let it rest on the other parts while the O2 sensor is installed. I did unclip the connector up in the engine bay and hang it from the hood so it would spin freely while installing it. A tip I saw elsewhere, thank you. Now push the CAT up into position and viola!. NO! WAIT! The mounting bracket is farther forward than on a stock CAT by about a ½ inch and slightly rotated off the axis of alignment from the engine bracket. The CAT won’t go all the way forward to mate with the exhaust manifold. So… Now it’s pushing, rotating and mild cursing to get it around the engine bracket. In the end, I got it together. Final decision on the bracket, it’s staying unbolted. Not the preferred method, but that’s how we’re rolling since I don't have a welder anymore to move the bracket on the CAT. At this point I was able to get my hand up to get the nuts on the ends of the bolts and finger tight them. Slide around to the front with the long extension and reach in to tighten them up. Now, if you’re lucky, you may have an air ratchet or a battery operated ratchet, which I did, to tighten them up. Do so at this point. Back to the middle of the car to reinstall the short pipe piece to the flex end of the CAT and to the tailpipe. Reinstall the middle skid plate support bracket and you’re just about complete. I hope for all of you who lasted this far have good luck getting around the secondaries if you still have them or figure an alternate plan for that. Time to start the car before I put everything back on and drop it to the ground. Hook up the battery (sparky, sparky), key in the ignition, hand pushing the brake AND… nothing. PANIC!!! I know there’s power. The interior lights come on, chime is going ding-ding. Again.. Nothing. Hold on, let’s breathe a second. Oh lord, the wife will kill me if I killed her car. 3rd time, small prayer to Stuttgart and… SHE LIVES AND BREATHES!!! And much quieter too. Do a couple of start-stop operations to double check it’s all working and then off to reinstall all the plastics and drop her to the ground. I will say, fighting to get the wheel liner on, is an extraordinary test of patience and will power. I think I fought that alone for over 30 minutes. If anyone has tips for that process, I’d be eternally grateful. Couple of side comments on this. The CAT I purchased was an aftermarket unit I got off of eBay and have no idea who manufactured it. There were no studs in the flanges, just 3 bolts and nuts per flange. I was worried they were going to fall out during the install, but the new gaskets held them in place as the holes were the right size to screw the bolts through them by hand. I know this helped during the reinstall and not having to bend or cut off the bracket on the CAT. For the heat shield, some places had said to unbolt the steering shaft and move out of the way entirely. I did not want that headache to do a realignment of the shaft/steering wheel. So I just did the minimum I thought would work. Now that you’ve gotten to the end of my story, I hope it will give someone else the courage to take on the project. Take your time, step back, breathe from time to time and don’t rush it. It will happen. Please make sure to tip your waitress. SHORT VERSION Put car on jackstands or at least front end Put rear of car on ramps if only jackstands in front Disconnect battery Remove front left tire Remove wheel well liner Remove underbody skidplates/plastics up to bumper Remove heat shield from steering shaft Remove middle skidplate support bracket Unbolt/snap off bolts from primary CAT flex pipe to tailpipe/secondary CAT Remove short tailpipe section if secondary delete performed From front of car, reach in and unbolt the 3 nuts holding primary CAT to exhaust manifold Drop CAT down and rest it on car Using O2 sensor socket, reach up into area and remove sensor Pull CAT out of car Push new CAT up into the void and rest on car Install O2 sensor Push CAT up to exhaust manifold and bolt together Install engine support bracket (if applicable) Install tailpipe section to flex pipe end of CAT Install skidplate support bracket Install skidplates Install wheel well liner Install tire Lower car to ground Install engine compartment plastics Reconnect battery Start car CELEBRATE Now if someone can share an easy way to do the passenger side......