Intermediate Pipe

Remove and replace the intermediate exhaust pipe connecting the exhaust manifolds to the muffler on a 1972 Ford F-100 with 302ci V8.

Warnings

Tools required

Parts

• Intermediate exhaust pipe × 1 — Use OEM specification or aftermarket equivalent
• Exhaust flange gaskets × 2 — 2.5" 2-bolt or 3-bolt style depending on manifold
• Exhaust flange bolts/nuts × 6 — 3/8" x 1" Grade 8 bolts with lock washers and nuts
• Exhaust pipe hanger rubbers × 2 — OEM style or universal fit

Preparation

1. Ensure engine and exhaust system are completely cold
2. Park vehicle on level ground and set parking brake
3. Place wheel chocks behind rear wheels
4. Raise front of vehicle with floor jack and support securely on jack stands at frame rails
5. Spray all exhaust flange bolts/nuts with penetrating oil and allow to soak for 15-30 minutes
6. Inspect intermediate pipe routing and note location of exhaust hangers

Procedure

1. 1

   Access intermediate pipe from underneath
   Position yourself under the vehicle with adequate lighting. Locate the intermediate pipe which runs from the dual exhaust manifold flanges at the front, along the driver side frame rail, and connects to the muffler inlet at the rear. Identify all connection points: front flange connections at exhaust manifolds (driver and passenger side), rear connection to muffler, and exhaust hangers supporting the pipe.
2. 2

   Disconnect rear connection to muffler
   Locate the slip-fit or flange connection where the intermediate pipe connects to the muffler inlet. If slip-fit style, loosen the U-bolt clamp nuts using a 9/16" socket and remove the clamp. If flange style, remove the 2 bolts connecting the intermediate pipe flange to the muffler flange using appropriate socket. Work the connection apart gently using a twisting motion. If seized, apply additional penetrating oil and use a pry bar or exhaust pipe spreader to separate.
3. 3

   Remove exhaust hanger supports
   Locate the 2 rubber exhaust hangers supporting the intermediate pipe along its length. Using a pry bar or by hand, unhook the pipe support rods from the rubber hangers mounted to the frame/crossmember. Note the orientation and position of hangers for reinstallation.
4. 4

   Disconnect driver side manifold flange
   Locate the flange connection where the intermediate pipe Y-section connects to the driver side exhaust manifold. Remove the 3 flange bolts/nuts using a 9/16" socket. The connection uses either studs with nuts or bolts through the flange. If fasteners are severely corroded and will not turn, apply heat with a propane torch or cut the bolts with a hacksaw if they cannot be saved. Remove and discard old gasket. Verified detail (1972 Ford exhaust manifold-to-pipe flange connections on the 302 are typically a 2-bolt flange, not 3-bolt. Also, a 1972 vehicle uses SAE fasteners (9/16"), not metric 15mm, which is anachronistic for this era Ford.): Remove the 2 flange bolts/nuts using a 9/16" socket.
5. 5

   Disconnect passenger side manifold flange
   Locate the flange connection where the intermediate pipe Y-section connects to the passenger side exhaust manifold. This connection may be more difficult to access. Remove the 3 flange bolts/nuts using a 9/16" socket. Work carefully to avoid rounding fasteners in the confined space. Remove and discard old gasket. Verified detail (Passenger side flange on the 302 is typically a 2-bolt pattern, not 3-bolt. The 15mm metric spec is anachronistic for a 1972 Ford, which uses SAE fasteners.): Remove the 2 flange bolts/nuts using a 9/16" socket.
6. 6

   Remove intermediate pipe assembly
   With all connections freed, carefully maneuver the intermediate pipe assembly down and out from under the vehicle. The Y-pipe configuration may require angling and rotating to clear the crossmember and frame components. If the pipe is stuck due to corrosion buildup at slip joints, use a rubber mallet to tap gently while pulling. Set aside the old pipe.
7. 7

   Clean exhaust manifold flanges
   Using a wire brush, thoroughly clean both exhaust manifold flange surfaces, removing all old gasket material, carbon deposits, and rust. The mating surface must be flat and clean to ensure proper seal with new gaskets. Inspect manifold flange studs or bolt holes for damage or stripped threads.
8. 8

   Prepare new intermediate pipe
   Inspect new intermediate pipe to confirm proper fit and configuration. Install new exhaust flange gaskets onto the Y-pipe flanges, ensuring they are positioned correctly with bolt holes aligned. Apply a light coating of anti-seize compound to the slip-fit connection end that will mate to the muffler to prevent future seizing.
9. 9

   Position new intermediate pipe
   Carefully maneuver the new intermediate pipe assembly into position under the vehicle. Align the Y-pipe flanges with both exhaust manifold flanges. The pipe should route along the driver side frame rail with support rod hangers positioned near their respective rubber mounts. You may need an assistant or temporary support to hold the pipe in position during installation.
10. 10

    Install passenger side flange connection
    Align the passenger side flange with new gasket to the exhaust manifold flange. Start all 3 bolts or nuts by hand to ensure proper thread engagement. Tighten in a star pattern to draw the flanges together evenly. Snug the fasteners but do not fully torque yet, allowing for adjustment.
11. 11

    Install driver side flange connection
    Align the driver side flange with new gasket to the exhaust manifold flange. Start all 3 bolts or nuts by hand. Tighten in a star pattern to draw the flanges together evenly. Snug the fasteners but do not fully torque yet.
12. 12

    Connect rear muffler connection
    Slide the intermediate pipe rear connection into the muffler inlet slip joint, ensuring approximately 2 inches of overlap. Align properly so pipe is not twisted or strained. If using U-bolt clamp, position clamp over the joint and install nuts finger-tight. If flange connection, align flanges with gasket and install bolts finger-tight.
13. 13

    Install exhaust hanger supports
    Hook the pipe support rods into the 2 rubber exhaust hangers mounted to the frame. Ensure hangers are fully seated and pipe is properly supported without excessive strain or misalignment. The pipe should hang with approximately 1 inch clearance from frame and body components.
14. 14

    Final tightening and alignment check
    Verify entire exhaust system alignment from manifolds to muffler. Check for proper clearance at all points with no contact to frame, crossmembers, or body. Working from front to rear, tighten all connections: driver side manifold flange bolts/nuts to snug (25-30 ft-lbs by feel), passenger side manifold flange bolts/nuts to snug (25-30 ft-lbs by feel), and rear muffler clamp or flange connection to snug. Recheck alignment after tightening each connection and adjust as needed.

Reassembly

1. Double-check all fasteners are properly tightened
2. Verify exhaust system has proper clearance at all points with no contact to frame or body
3. Ensure exhaust hangers are properly seated and supporting the system

Verification

• Lower vehicle from jack stands
• Start engine and listen for exhaust leaks at all flange connections - a ticking or hissing sound indicates leak
• With engine running, carefully inspect all connections for visible exhaust gas escaping
• Rev engine to 2000-2500 RPM and verify no abnormal sounds or leaks develop under load
• Allow engine to reach operating temperature and recheck for leaks as thermal expansion occurs
• Test drive vehicle and listen for rattles, buzzing, or contact between exhaust and chassis components
• After first 50-100 miles, recheck all flange bolts/nuts for proper tightness as exhaust systems often require retorquing after heat cycling

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