MBE 900 – Section 1.19 Rocker Arm

Section 1.19
Rocker Arm

‪

Section 1.19.1
Rocker Arm Assembly Removal

Remove the rocker arm assembly as follows:‪

1. Remove the cylinder head cover. Refer to "1.1.1 Cylinder Head Cover Removal" .
2. Remove each rocker arm mounting bolt and the clamping piece under it. Remove the rocker arm assembly. See Figure "Rocker Arm Assembly" .

   Note: The 6-cylinder engine is shown; the 4-cylinder engine is similar.

   

   1. Cylinder Head Cover‪	5. Valve Bridge‪
   2. Rocker Arm Mounting Bolt‪	6. Pushrod‪
   3. Clamping Piece‪	7. Cap‪
   4. Rocker Arm Assembly‪

   Figure 1. Rocker Arm Assembly

3. Remove a cap from the end of the valve stem on each exhaust valve.
4. Remove the valve bridge from each set of intake valves.

Section 1.19.1.1
Rocker Arm Inspection

Inspect the rocker arm as follows:‪

1. Inspect the rocker arm assembly for wear. If necessary, disassemble the rocker arm assembly and replace any worn parts.
2. Inspect the valve bridges for wear. If necessary, replace any worn valve bridge(s).

Section 1.19.2
Rocker Arm Disassembly

Disassemble the rocker arm as follows:‪

1. Remove the rocker arm assembly from the cylinder head. Refer to "1.19.1 Rocker Arm Assembly Removal" .
2. Remove the spring clips from each end of the rocker arm shaft. See Figure "Rocker Arm Components" .

   Note: The 6-cylinder engine is shown; the 4-cylinder engine is similar. Dimensions are the same on both engines.

   

   1. Spring Clip (front)‪	6. Exhaust Rocker Arm‪
   2. Front Bracket‪	7. Spring‪
   3. Inside Bracket‪	8. Shaft‪
   4. Rear Bracket‪	9. Washer(s)‪
   5. Intake Rocker Arm‪

   Figure 2. Rocker Arm Components

3. Remove the rocker arm brackets, rocker arms, washers, and springs from the rocker arm shaft. Keep all parts in order, as removed, for ease of assembly.
   1. Starting from one end of the shaft, remove the front (or rear) bracket and washer.
   2. Remove the first intake (exhaust) rocker arm.
   3. Remove the spring between the intake and the exhaust rocker arm.
   4. Remove the first exhaust (intake) rocker arm.
   5. Remove the first inside bracket and washers.
   6. Continue removing rocker arms, springs, brackets, and washers until done.
4. Inspect the parts of the rocker arm assembly for wear, and replace if necessary.

Section 1.19.2.1
Rocker Arm Bushing and Shaft Inspection

Inspect the disassembled rocker arm as follows:‪

1. Inspect the inside diameter of the rocker arm bushing. Replace the rocker arm bushing if the inside diameter is smaller than 22.000 mm (0.8661 in.) or larger than 22.021 mm (0.8670 in.).
2. Inspect the diameter of the rocker arm shaft. Replace the rocker arm shaft if the diameter is smaller than 21.967 mm (0.8648 in.) or larger than 21.980 mm (0.8654 in.).

Section 1.19.3
Rocker Arm Assembly

Assemble the rocker arm as follows:‪

1. Install a spring clip on one end of the rocker arm shaft.
2. Install the rocker arm brackets, rocker arms, washers, and springs on the rocker arm shaft, starting from the closed end (with spring clip installed) and working towards the open end. Install all assembly components in order, as removed.
3. When installing the front and rear rocker arm brackets, pay close attention to the distance between the outer brackets and the inner brackets, as measured from hole to hole. See Figure "Rocker Arm Components" .
   

   1. Spring Clip (front)‪	6. Exhaust Rocker Arm‪
   2. Front Bracket‪	7. Spring‪
   3. Inside Bracket‪	8. Shaft‪
   4. Rear Bracket‪	9. Washer(s)‪
   5. Intake Rocker Arm‪

   Figure 3. Rocker Arm Components

   Description‪	Specifications‪
   Bushing Inside Diameter (when installed)‪	22.00-22.021 mm (0.8661-0.8670 in.)‪
   Shaft Diameter‪	21.967-21.980 mm (0.8648-0.8654 in.)‪
   Rocker Arm Mounting Bolt Torque‪	30 N·m (22 lb·ft)‪
   Distance from Front Bracket to First Inside Bracket (see Figure , A)‪	122 mm (4.80 in.)‪
   Distance from Last Inside Bracket to Rear Bracket (see Figure , B) ‪	110 mm (4.33 in.)‪

   Table 4. Rocker Arm Specifications
   1. The distance between the front bracket and the first inside bracket (Dimension "A") must equal 122 mm (4.80 in.).
   2. The distance between the last inside bracket and the rear bracket (Dimension "B") must equal 110 mm (4.33 in.).
4. When the assembly is complete, secure the assembly by installing a spring clip on the other end of the rocker arm shaft.
5. Install the rocker arm assembly on the cylinder head.

Section 1.19.4
Rocker Arm Assembly Installation

Install the rocker arm assembly as follows:‪

1. Install a valve bridge on each set of intake valves.
2. Install a cap on the end of each exhaust valve stem.
3. Inspect each pushrod to be sure it is correctly installed in its tappet.
4. Install the rocker arm assembly. See Figure "Rocker Arm Mounting" .
   

   1. Mounting Bolts‪

   2. Clamping Piece‪

   Figure 4. Rocker Arm Mounting

   1. Position the rocker arm assembly on the cylinder head so that the mounting bolts can be inserted into the holes in the cylinder head.
   2. Install a clamping piece on each rocker arm and run a mounting bolt through it.
   3. Tighten each mounting bolt 30 N·m (22 lb·ft).
5. Adjust the valve lash. Refer to "1.17.3 Adjusting Valve Lash" .
6. Install the cylinder head cover. Refer to "1.1.2 Cylinder Head Cover Installation" .