How to Replace the Catalytic Converter in a 2005 Ford F-150

The 2005 Ford F-150 was just a year removed from the complete redesign that dropped the rounded body in favor of a more truck-like appearance. The 2005 F-150 came standard with a 202-horsepower, 4.2-liter V-6 engine and used a dual catalytic converter system to stay compliant with federal emission regulations. Upon first glance, this dual catalytic converter system appears to be one piece, but once you remove it, you can separate the sides and replace one catalytic converter. Replacing the base level 2005 F-150s catalytic converter is a detailed task that requires a precise alignment process afterward.

Instructions

Removal

1

Park the F-150 on a level surface and allow it to sit until the engine is cool to the touch. Wait an additional hour to allow the catalytic converters to cool. Position wheel chocks under the rear of the rear wheels. Raise the front of the vehicle with a floor jack and slide jack stands under the frame rails. Lower the vehicle onto the jack stands.

2

Unbolt the skid plate from under the exhaust system, using a ratchet and socket, if your F-150 has a skid plate. Lower the skid plate and remove it from under the truck.

3

Find the catalyst monitors screwed into the exhaust pipe just behind each catalytic convertor. Unplug the wiring harness from each monitor.

4

Loosen the coupling securing the catalytic converter Y-pipe assembly to the intermediate pipe the pipe leading to the rear of the truck using a ratchet and socket. Slide this coupling onto the intermediate pipe.

5

Trace the right side catalytic converter Y-pipe assembly until you find the crossover pipe, the pipe connecting the right and left side of the Y-pipe assembly connect. Loosen the clamp securing the crossover pipe to the left side of the Y-pipe, using a ratchet and socket.

6

Remove the nuts securing the left side of the catalytic converter Y-pipe assembly to the exhaust manifold, then the right side, using a ratchet and socket.

7

Remove the bolts securing the catalytic converter heat shield to the transmission crossmember, using a ratchet and socket, then lower the heat shield.

8

Apply a generous coat of penetrating oil to the base of the catalyst monitors and allow the oil to set to the time specified by its instructions. Remove the catalyst monitors, using a ratchet and oxygen sensor socket.

9

Instruct an assistant to lay under the truck with you and hold the catalytic converter Y-pipe assembly to prevent it from falling. Remove the two bolts securing the Y-pipe assemblys mount to the rear transmission crossmember, using a ratchet and socket.

10

Separate the left half of the Y-pipe assembly from the right and you and your assistant each lower one half of the assembly from the truck.

11

Discard the failed catalytic converter, as you do not need to replace the entire assembly if only one catalytic converter fails. Remove the Y-pipe assembly mount from the left side of the Y-pipe assembly, if that is the side you are replacing, by prying its rubber hanger from the arm.

12

Pull the old flange gaskets from the Y-pipe assembly and discard them.

Installation

13

Press the Y-pipe assembly mounts rubber hanger onto the left side of the Y-pipe assembly, if you are replacing the left side of the assembly.

14

Pull the old Y-pipe-to-intermediate pipe coupler from the intermediate pipe and replace it with a new one, but do not tighten it.

15

Set new flange gaskets on the manifold end of right side of the Y-pipe assembly. Lift the right side of the Y-pipe assembly into place under the truck, with your assistants help. Align the Y-pipe mount bolt holes with those in the transmission crossmember and hand-thread the bolts. Hand-thread the catalytic converter-to-exhaust manifold nuts. Slide a new exhaust clamp onto the right side crossover pipe.

16

Apply a thin coat of an anti-seize compound to the right hand catalyst monitors threads and hand-thread it into the right side catalytic converter pipe. Torque the catalyst monitor to 30 foot-pounds, using a torque wrench and oxygen sensor socket.

17

Lift the left side of the Y-pipe assembly into place and hand-tighten the catalytic converter-to-exhaust manifold nuts. Slide the left side of the Y-pipe assembly into the right sides pipe

18

Apply a coat of an anti-seize compound to the left side catalyst monitors threads and hand-tighten the catalyst monitor behind the left side catalytic converter. Tighten the monitor to 30 foot-pounds.

19

Clean any rust from the coupler mounting point on the intermediate pipe and Y-pipe assembly with an abrasive pad.

20

Tighten the lowermost left side catalytic converter-to-exhaust manifold nut to 15 foot-pounds, using a torque wrench and socket. Tighten the upper left side catalytic converter-to-exhaust manifold nut to 30 foot-pounds, then tighten the lowermost nut to 30 foot-pounds. Repeat this step on the right side catalytic converter-to-exhaust manifold bolts.

21

Lift the heat shield into place and tighten its bolts to the transmission crossmember to 11 foot-pounds.

22

Connect the catalyst monitors wiring harnesses to the F-150s wiring. If your F-150 has a skid plate lift it into place and tighten its retaining bolts with a ratchet and socket.

23

Press the right side of the Y-pipe assembly toward the left side, so the protrusion on the left side pipe slides into the notch on the right side pipe. Have your assistant hold the pipes in this position while you slide the exhaust clamp over this connection and tighten the clamp to 35 foot-pounds.

24

Press upward or downward on the crossover pipe until it is parallel with the transmission crossmember, then tighten the Y-pipe assembly mount bolts to 22 foot-pounds.

25

Measure the gap between the Y-pipe assembly and the intermediate pipe, using a ruler. At this point it should be a 1/5-inch gap at the most. If it is any wider than this, loosen the crossover pipe clamp and Y-pipe assembly mount and restart the process from Step 11.

26

Slide the coupler into place between the Y-pipe assembly and the intermediate pipe. Tighten the couplers front nut to 35 foot-pounds, ten tighten the rear nut to 35 foot-pounds. Re-tighten the front nut to 35 foot-pounds.

27

Lift the truck off the jack stands and remove the stands. Lower the vehicle to the ground and start its engine. Verify that there are no exhaust leaks.