Valve Spring: Service and Repair

REMOVAL - CYLINDER HEAD OFF





1. With cylinder head removed, compress valve springs using the valve spring compressors shown in (Fig. 50).
2. Remove valve retaining locks, valve spring retainers and valve springs.
3. Remove valve stem seal assembly.

REMOVAL - CYLINDER HEAD ON
1. Perform fuel system pressure release procedure before attempting any repairs.
2. Disconnect negative cable from battery.
3. Remove air cleaner housing and hose assembly.
4. Remove upper intake manifold.
5. Remove cylinder head covers.
6. Remove rocker arm and shaft assembly.
7. Remove spark plugs.
8. Rotate the crankshaft clockwise, until the number 1 piston is at Top Dead Center (TDC) on the compression stroke.
9. With air hose attached to spark plug adapter installed in number 1 spark plug hole, apply 620.5 to 689 kPa (90 to 100 psi) air pressure. This is to hold valves into place while servicing components.
10. Using Tool MD 998772A with adapter 6527 or equivalent, compress valve spring and remove valve locks, retainer, and valve spring.
11. Remove valve stem seal, if required.
12. Follow the same procedure on the remaining 5 cylinders using the firing sequence 1 - 2 - 3 - 4 - 5 - 6. Make sure piston is at TDC in each cylinder of the valve spring that is being removed.
13. Remove spark plug adapter tool.

INSPECTION





When valves have been removed for inspection, reconditioning or replacement, valve springs should be tested (Fig. 51). As an example; the compression length of the spring to be tested is 38.00 mm (1.496 inch). Turn table of Tool C-647 until surface is in line with the 38.00 mm (1.496 inches) mark on the threaded stud and the zero mark on the front. Place spring over stud on the table and lift compressing lever to set tone device. Pull on torque wrench until ping is heard. Take reading on torque wrench at this instant. Multiply this reading by two. This will give the spring load at test length. Fractional measurements are indicated on the table for finer adjustments. Refer to Engine Specifications to obtain specified height and allowable tensions. Replace springs that do not meet specifications.

INSTALLATION - CYLINDER HEAD OFF
1. Install valves if removed.





2. Install valve stem seal/spring seat assembly over valve guides on all valve stems (Fig. 53). Ensure that the garter spring is intact around the top of the rubber seal.
3. Place valve springs (color-coded end facing up) and valve retainers into position.





4. Compress valve springs with a valve spring compressor. Install locks and release tool. If valves and/or seats are reground, measure the installed height of springs (B) (Fig. 52), make sure measurements are taken from top of spring seat to the bottom surface of spring retainer. If height is greater than 38.75 mm (1.5256 inch), install a 0.762 mm (0.030 inch) spacer in head counterbore under the valve spring seat to bring spring height back within specification.

INSTALLATION - CYLINDER HEAD ON
1. Compress valve spring using Special Tool MD 998772A with Adapter 6527 only enough to install retainer and locks.
2. After installing locks, release tension on valve spring and verify proper installation.
3. Remove Special Tool MD 998772A.
4. Install rocker arm and shaft assembly.
5. Install cylinder head covers.
6. Install spark plugs.
7. Install upper intake manifold.
8. Connect negative cable.