Exhaust Pipe - Rear Section

This procedure covers the removal and replacement of the rear exhaust pipe section on a 1972 Ford F-100 with 302ci V8 engine, from the intermediate pipe connection to the tailpipe outlet.

Warnings

Tools required

Parts

• Rear exhaust pipe section × 1 — Use OEM specification or equivalent aftermarket
• Exhaust flange gasket × 1 — 2-bolt flange gasket 2.25 inch
• Exhaust flange bolts and nuts × 2 — 3/8-16 x 1.25 inch grade 8
• Exhaust hanger insulators × 2 — Replace if cracked or deteriorated

Preparation

1. Park vehicle on level ground and engage parking brake
2. Place wheel chocks in front of and behind front wheels
3. Allow exhaust system to cool completely if vehicle was recently operated
4. Raise rear of vehicle using floor jack at rear axle housing or frame rails
5. Support vehicle securely on jack stands placed at frame rails behind cab
6. Inspect exhaust hangers and routing to confirm rear section attachment points
7. Apply penetrating oil liberally to all exhaust flange bolts and allow to soak for 15-20 minutes

Procedure

1. 1

   Locate and mark exhaust connection points
   Identify the forward flange connection where the rear exhaust section bolts to the intermediate pipe, typically located just ahead of or above the rear axle. Identify the 2 rubber exhaust hangers that support the rear section, typically one near the rear axle and one near the rear bumper. Take note of pipe routing for reinstallation.
2. 2

   Support the rear exhaust section
   Position a floor jack or suitable support under the rear muffler or tailpipe to prevent the section from falling when disconnected. Adjust height to take weight off the exhaust hangers without stressing the pipe.
3. 3

   Remove exhaust hanger insulators
   Starting at the rearmost hanger, use a pry bar or exhaust hanger removal tool to separate the exhaust pipe hook from the rubber insulator. Work the hook out of the rubber grommet by prying and twisting. Repeat for the forward hanger on the rear section. The pipe should now be supported only by the forward flange connection and your jack.
4. 4

   Remove forward flange connection bolts
   Using a 9/16 inch wrench and socket, remove the 2 bolts securing the rear exhaust section flange to the intermediate pipe flange. Hold the nut on the backside with the wrench while turning the bolt from the front with the socket. If bolts are severely corroded and will not turn, apply additional penetrating oil and heat with a propane torch, or cut the bolts with a reciprocating saw. Verified detail (A 1972 Ford F-100 uses SAE fasteners, not metric. The 3/8-16 bolts specified in the parts list would require 9/16 inch wrenches and sockets, not 15mm.): Using a 9/16 inch wrench and socket, remove the 2 bolts securing the rear exhaust section flange to the intermediate pipe flange.
5. 5

   Separate the flange connection
   Once bolts are removed, separate the flanges by pulling the rear section rearward. The flanges may be stuck together due to corrosion and exhaust residue. Use a pry bar between the flanges if necessary, taking care not to damage the intermediate pipe flange surface. Rock the pipe side to side while pulling to break it free.
6. 6

   Lower and remove rear exhaust section
   With the flange separated, carefully lower the floor jack supporting the rear section. Guide the tailpipe out from under the vehicle, maneuvering around the rear axle and frame components. Remove the old flange gasket from the intermediate pipe and discard.
7. 7

   Clean flange mating surfaces
   Using a wire brush and scraper, thoroughly clean the flange face on the intermediate pipe. Remove all old gasket material, carbon buildup, and corrosion to ensure a proper seal with the new gasket. Clean the bolt holes with a wire brush or thread chaser if necessary.
8. 8

   Inspect and replace rubber hangers if needed
   Inspect the 2 rubber exhaust hanger insulators for cracks, tears, or deterioration. If the rubber is hardened, cracked, or the mounting holes are elongated, remove the old insulators from the frame-mounted brackets and install new ones. The insulators should fit snugly on the bracket pins.
9. 9

   Position new rear exhaust section
   Maneuver the new rear exhaust section into position under the vehicle, routing the tailpipe past the rear axle and frame components. Support the section with a floor jack positioned under the muffler. Align the forward flange with the intermediate pipe flange.
10. 10

    Install new flange gasket and bolts
    Place the new exhaust flange gasket between the intermediate pipe flange and the rear section flange, ensuring bolt holes are aligned. Insert the 2 new flange bolts from the front side and start the nuts on the back side by hand. Do not fully tighten yet.
11. 11

    Install exhaust hangers
    With the flange connection loose, adjust the rear exhaust section position to align the pipe hooks with the rubber hanger insulators. Work each hook into its corresponding rubber grommet, starting with the forward hanger. You may need to raise or lower the floor jack slightly to facilitate installation. Use a pry bar or lubricant (soapy water) to help slip the hooks into the insulators if needed.
12. 12

    Align and tighten flange connection
    With all hangers installed, verify the rear exhaust section is properly aligned with adequate clearance from the frame, body, rear axle, and any underbody fuel tank if so equipped. The tailpipe should exit cleanly without binding. Tighten the 2 flange bolts evenly using a 9/16 inch socket and wrench, alternating between bolts. Tighten securely but avoid overtightening, which can distort the flanges or crack the pipe. Typical specification is approximately 20-25 ft-lbs, though no factory specification is documented for this application. Verified detail (A 1972 Ford F-100 uses SAE fasteners, not metric. The 3/8-16 bolts specified in the parts list would require 9/16 inch wrenches and sockets, not 15mm.): Tighten the 2 flange bolts evenly using a 9/16 inch socket and wrench, alternating between bolts.
13. 13

    Remove jack support and verify clearances
    Remove the floor jack from under the rear exhaust section. Visually inspect the entire rear section to verify it hangs properly with adequate clearance from all surrounding components. Check that rubber hangers are not overstretched and that the tailpipe exits straight. Push up and down on the tailpipe to verify the system has proper flexibility and returns to center.

Reassembly

1. Lower vehicle from jack stands when all clearances are verified
2. Remove wheel chocks and release parking brake

Verification

• Start engine and allow to idle while inspecting the flange connection for exhaust leaks
• Listen for hissing or popping sounds at the flange joint that would indicate a leak
• Rev engine to 2000 RPM and verify no unusual exhaust noises or rattles
• Check that no exhaust components contact the frame, body, or driveline during engine vibration
• Test drive vehicle and verify exhaust tone is normal with no leaks, rattles, or vibrations
• After test drive, re-inspect flange connection and verify bolts remain tight

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