H/X pipe install 79+ Mustangs:
NOTE: Proceed at your own risk, as the author of this article will take no responsibility for any damaging effects caused by following (or not following) the instructions herein. *DON'T FORGET WHICH BOLTS GO WHERE* This article written by Ashentep, please do not copy without proper credit.
**PICTURES COMING SOON**
Tools/Supplies needed:
15mm & 18mm Metric sockets in 1/2" and/or
3/8" drives
butterfly impact is a huge help
assorted extensions (short, medium, long, very long, very very long, and
ridiculously long)
7/8" combo wrench (for O2 sensors)
WD-40 and/or PB Blaster
at least 2 jack stands and jack 4 stands and/or 2 stands and 2 ramps would be
better (or preferably a lift)
basic mechanical understanding
1-2 hours free time
1. Raise vehicle on ramps or jackstands. The choice is yours, but the more room you
can get, the better. The best choice seems to be raising the rear on ramps, and the front
on jackstands, since you'll be working in the front, and jackstands can hold the vehicle
higher. MAKE SURE VEHICLE IS SECURE BEFORE WORKING UNDER CAR!!!!
2. Climb under car (duh!), and unplug O2 sensors (the front O2 sensors on 3.8 cars are in the headers, and do not need to be unplugged or removed). Using a 7/8" O2 socket, or for most of us, a 7/8" wrench, loosen, and remove the O2 sensors for a bit more working room (again, 3.8 cars do not need the front sensors removed). Remember that on '96+ cars, there are 4 O2 sensors! If your car has the factory air fitting for the 5.0 cars, loosen the clamp and remove the air pipe from the factory H pipe. PB Blaster helps free the pipe. If the air pipe has never been removed, it may be necessary to cut the tube. A high heat silcone hose can be used to patch it upon reassembly.
3. Loosen 4 rear bolts holding X-pipe in place (14mm on my '95GT and '01 Cobra but CHECK yours to make sure you use the CORRECT sized socket). Now move to the front and use an 18mm deep well socket ('95 GT and '01 Cobra, but again check yours) on long extensions to reach the nuts. Its a straight shot for each on every car I've done this on, but again, yours may differ.
4. Once all nuts are loose, remove rear nuts first, and unseat the rear of the stock H from the catback. This takes a bit of muscle sometimes. once the rear is free, move to the front and remove the nuts.
5. Now all that holds the H pipe in place on some models are two rubber hangers. If your replacement H/X has provisions for the hangers, spray some WD-40 or similar on them, and work them off the H-pipe. If your H/X does NOT have the provision, cut the rubber hangers to make life easy for yourself. The H pipe will now fall right out, but be careful, as its not very light! Drag the H clear of the car.
6. I like to put the O2 sensors on the new H/X pipe after it is installed, but if you wish to install them now, go right ahead. I leave them off as they it leaves more room for reinstalling the front hardware. Drag the H/X pipe under the car, and place the front of the pipe into place on the headers. (*If you are installing this on a 4.6 car, and not using a new passenger side header/H/X pipe seal, then spread some copper RTV on the old seal. This will help prevent leaks*). If the pipe came in two (or more) pieces, now is the time to install the small section on the driver's side (or both side sections of a 3+ piece H/X pipe) and loosly install the hardware. Loosly install the mounting nuts.
7. Raise the rear of the H/X pipe and loosly install the mounting nuts. If the H/X came with hanger provisions, go ahead and place these in the stock rubber hangers.
8. If the H/X didn't come with hangers, place a floor jack under the H/X, and raise it to an appropriate height. If you skip this step (especially the 2 piece pipes), the H/X will hang down extremly low and scrape a lot (ask me how I know!). Once the H/X is to an appropriate height, go back and tighten the front and rear hardware (as well as the hardware that attaches the piece if its a 2+ piece pipe). Lower the jack, and check the height of the H/X. If it hangs too low for your taste, go back and loosen the hardware, raise the pipe with the jack and retighten again.
9. Place the O2 sensors on the new H/X pipe and plug the front two sensors in. If you have MIL eliminators as well, plug them inline with the two rear sensors. If you do not, simply plug the rear O2s back in, but be aware that you will have a check engine light due to the fact that the rear O2 sensors will be reading as if the cats are not working (duh! They're not there!).
10. Crank car before lowering to listen for exhaust leaks. If you hear any, tighten the bolts! You may need to use a breaker bar, or some sort of pipe to get leverage on the bolts. After all leaks are cleared, lower car and test drive.
Note: After installation on 5.0s with the factory air pump, unless the new H/X pipe comes with a provision to install the air tube, it will be necessary to either short belt the air pump, or install a air pump delete kit. Also note that if this is not done, you will have a loud whine from under the car from the air tube. It is also good to remove the smog pump as well as the air tubes, and plug the heads where the tubes meet them with the correct sized bolt (5/8" coarse thread). This will prevent any problems.