How To: Remove the Exhaust Precats
Disclaimer
I am in no way responsible for what you do on your own time with your own hands to your own car. The following information is provided for informational purposes only. Assume the worst, that the following modification COULD cause damage to your vehicle. If you choose to modify your car it is your own business and I'm not part of the equation.
This tutorial shows how to gut the precats on a Contour SVT, Mercury Cougar and Mercury Mystique. Everything in here was done on a lift, but it can be done on jack stands (like I did just a little less room and more dirty.) In this tutorial the precats were not removed from the car---if you do this on jackstands, you will prolly have to remove the precats (just more bolts to unhook from the exhaust manifold), but you can reach them all from under the car. It is best to remove them to ensure that all the dust and material is removed. Left over material could cause some long term engine damage.
These are all the tools we used. You may not need all of these, but its everything that we used. Here is the break down.
1 A drill
2 Hammer
3 A tap thread for a bolt
4 thick malleable wire (bucket handle or welding rods)
5 U joints for a ratchet
6 7/8" wrench
7 Rod
8 long ass screwdriver
9 15mm extended socket
10 air ratchet
The arrow is pointing to the front precat. In this car there are two. The circle shows the bolts you must remove. The 15mm socket is used for all the bolts. The 7/8" wrench is used to remove the o2 sensors. There is a sensor before and after each precat. You want to remove the sensor AFTER each precat, so you will have two to remove. Be very careful with the o2 sensors and be sure not to get them mixed up. After you've removed those bolts, go to the other end of the y pipe.
The circle shows more bolts to remove. After removing all those bolts (and there is also one more not show, it holds the pipe up) you can remove the Y pipe. Also dont forget the o2 sensor. The arrow shows the 2nd precat.
This is a shot of the rear cat. it is the easiest to do. What you see inside is the honeycomb material covered in platinum, this all has to come out. On this precat, its easy. Just take a big ass screwdriver or crow bar and jam the shit out of it until everything falls out. There will be a felt peice when you are almost done. Make sure you get it all. Be very careful not to hit or damage the upper o2 sensor. You may also want to remove the upper o2 sensor so you dont mash it accidently. Inspect the insides with a flashlight and make sure its smooth and all the metal is gone.
This is what it should look like after you are done. Looks like youll get a a bit more airflow eh??
This is all the shit that will fall out. Alot of it will simply shatter into dust, but you will get some big chunks and some felt peices. Wear a respirator if you have it, and safety goggles, its not good to breathe this and its not good in your eyes either, it will get everywhere.
This is the bottom of the front precat. Due to the bend, you cannot simply stick a screwdriver in it like you did the other one. You can either Remove it or Drill a small hole (1/4") on the bottom. Take the metal stick (bucket handle / welding rod whatever) and attach it to the drill. bend a 90 angle at the end and slide it into the hole. Turn the drill on and with a hammering motion work at that shit till it falls down. This part will take a while. You can then use a screwdriver and push out all the shit that fell down through the side using the o2 sensor hole. This precat will take 10x longer than the first, because you have no big openning, but you can get it all out this way and not have to remove the bolts from the exhaust manifold.
This is a shot of the drill in the precat hole. Just work this way for an hour or so and itll all falls out. When you see all the felt come down from up top, its almost done. Once again becareful not to damage the upper o2 sensor. Then double check the walls and make sure its all smooth and clean. Bang the edges with a hammer and make sure it all falls out. You dont want any loose peices in there because when you finally hook it back up it may clog you main cat.
Use the tap to thread a hole for a 1/4" bolt.
Apply threading sealant to the bolt and seal the hole. Now, with the y pipe still off, start the car and rev the gas a few times. You want to blow out anything that is in the pipes and have it blow onto the ground, instead of through your exhaust. Your car will sound so loud and awesome, you will contemplate leaving the y pipe out and running open headers.
Use an air compressor or vacum and clean out the y pipe before puting it back on. Then bolt everything back in place.
Reattach the o2 sensors (remember not to get them mixed up). Zip tie them so no wires will touch any metal/hot parts (there are factory clips you can zip tie to). Reset the main computer by taking off the positive terminal going to the battery and shorting it to the negative then let it sit a few mins. Reattach and start your car. Be sure to check for leaks.
This all can take any where from about 2 1/2 hours to about 6 hours depending on how smooth things go.
Friends Cars
My 2000 Contour SVT
Lay's 1998 Contour SVT
Ben's 2001 Mustang GT
Julian's 2003 Mustang GT
Daniel's 2000 Camaro
