Valve Guide Seal: Service and Repair
VALVE STEM SEALREMOVAL AND INSTALLATION
CAUTION:
*Remove and assemble the marked parts in each cylinder unit.
Pre-removal & Post-installation Operation:
Removal Steps 1-19:
Required Special Tools:
^ MD998772: Valve Spring Compressor
^ MB992089: Retainer Holder C
^ MB992090: Retainer Holder Attachment
^ MB992085: Valve Stem Seal Pliers
^ MD998737: Valve Stem Seal Installer
REMOVAL SERVICE POINTS
[A] FRONT CAMSHAFT BEARING CAP ASSEMBLY REMOVAL
CAUTION:
Be careful not to drop the camshaft bearing.
Loosen the mounting bolts of front camshaft bearing cap in the order of number shown in the figure, and remove the front camshaft bearing cap assembly.
[B] OIL FEEDING CAMSHAFT BEARING CAP/CAMSHAFT BEARING CAP/THRUST CAMSHAFT BEARING CAP REMOVAL
CAUTION:
When the camshaft bearing cap mounting bolts are loosened at once, the mounting bolts jump out by the spring force and the threads are damaged. Always loosen the mounting bolts in four or five steps.
Loosen the mounting bolts of the camshaft bearing caps in the order of number shown in the figure in four or five steps, and remove the camshaft bearing caps.
[C] VALVE TAPPET REMOVAL
CAUTION:
^ Do not use pliers or other tools to remove the valve tappets. Always remove them by hand.
^ When reusing the removed valve tappet, it has to be installed in the same position as before. Be sure to put a tab that shows the original installation position on the valve tappet when storing it.
Remove all of the valve tappets by hand.
[D] VALVE SPRING RETAINER LOCK REMOVAL
1. Screw in special tool MB992090 to special tool MD998772 and assemble special tool MB992089.
CAUTION:
When removing the valve spring retainer lock, leave the piston of the cylinder in the TDC (Top Dead Center) position. The valve may fall into the cylinder if the piston is not properly in the TDC position.
2. Install special tool MD998772 (with special tools MB992090 and MB992089 attached) to the cylinder head and compress the valve spring. Then, remove the valve spring retainer lock.
[E] VALVE STEM SEAL REMOVAL
Use special tool MB992085 to grip the base of the stem seal (where the outside diameter is larger) securely, and remove it by twisting it to the left and right.
INSTALLATION SERVICE POINTS
[A] VALVE STEM SEAL INSTALLATION
CAUTION:
^ Valve stem seals cannot be reused.
^ Do not damage the wall of the tappet hole when installing the valve stem seal.
^ Special tool MD998737 must be used to install the valve stem seal. Improper installation of the valve stem seal could result in oil leaking past the valve guide.
1. Apply a small amount of engine oil to the press-fit part and lip part of the new valve stem seal.
2. Use special tool MD998737 to press-fit a new valve stem seal in the valve guide using the valve stem area as a guide.
[B] VALVE SPRING INSTALLATION
Install the valve spring so that the painted side faces toward the camshaft.
[C] VALVE SPRING RETAINER LOCK INSTALLATION
In the same manner as removal, use special tool MD998772 with special tool MB992090 and special tool MB992089 attached to compress the valve spring, and install the valve spring retainer lock.
[D] VALVE TAPPET INSTALLATION
1. Apply a small amount of engine oil to the valve tappets.
CAUTION:
Be sure to install the valve tappets in the same position as before.
2. Install the valve tappet to the cylinder head.
[E] THRUST CAMSHAFT BEARING CAP/CAMSHAFT BEARING CAP/OIL FEEDING CAMSHAFT BEARING CAP INSTALLATION
1. Install the camshaft bearing caps to the cylinder heads.
NOTE: Because the thrust camshaft bearing cap and camshaft bearing cap are the same in shape, check the cap number and additionally its symbol to identify the intake and exhaust sides for correct installation.
2. Tighten each camshaft bearing cap to the specified torque in the order of number shown in the figure in two or three steps.
Tightening torque: 12 ± 1 Nm (107 ± 8 in-lb)
[F] CAMSHAFT BEARING/CAMSHAFT AND CAMSHAFT SPROCKET ASSEMBLY (EXHAUST SIDE) INSTALLATION
CAUTION:
^ Be careful not to drop the camshaft bearing.
^ When installing the camshaft and camshaft sprocket assembly (exhaust side), be careful not to let the camshaft bearing which is installed to the front cam bearing deviate from its position.
When replacing the camshaft bearing, according to the identification mark of front camshaft bearing cap in the table below, select a camshaft bearing with the corresponding size. Note that the identification mark of camshaft bearing is stamped on the place shown in the figure.
[G] FRONT CAMSHAFT BEARING CAP ASSEMBLY INSTALLATION
CAUTION:
When the mounting bolts are tightened with the front camshaft bearing cap tilted, the front camshaft bearing cap is damaged. Install the front camshaft bearing cap properly to the cylinder head and camshaft.
1. Install the front camshaft bearing cap to the cylinder head, and temporarily tighten the front camshaft bearing cap to the specified torque in the order of the figure (1).
Tightening torque: 17 ± 3 Nm (13 ± 2 ft-lb)
2. Tighten the front camshaft bearing cap again to the specified torque in the order of the figure (2).
Tightening torque: 30 ± 2 Nm (23 ± 1 ft-lb)