Valve Spring: Service and Repair
REMOVALIN VEHICLE
1. Perform fuel system pressure release procedure before attempting any repairs.
2. Disconnect negative cable from remote jumper terminal.
3. Remove air cleaner housing and inlet hose.
4. Remove upper intake manifold.
5. Remove cylinder head covers.
6. Remove crankshaft vibration damper, timing chain cover, and timing chain.
7. Remove camshafts and rocker arms.
8. With air hose attached to spark plug adapter installed in the cylinder being serviced, apply 620.5 - 689 kPa (90 - 100 psi) air pressure. This is to hold valves in place while servicing components.
9. Using Special Tool MD 998772A with adapter 6779, compress valve spring and remove valve locks, retainer, and valve spring.
10. Remove valve stem seal.
OFF VEHICLE
1. With cylinder head removed, compress valve springs using a Special Tool C-3422-B, Valve Spring Compressor.
2. Remove valve retaining locks, valve spring retainers, valve springs and valve spring seat/stem seal assembly (Fig. 39).
INSPECTION
Whenever valves have been removed for inspection, reconditioning or replacement, valve springs should be tested (Fig. 40). As an example; the compression length of a spring to be tested is 38.00 mm (1.496 inch). Turn the table of Tool C-647 until surface is in line with the 38.00 mm (1.496 inch) 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 Specifications to obtain specified height and allowable tensions. Replace any springs that do not meet specifications.
INSTALLATION
IN VEHICLE
1. The valve stem seal/valve spring seat should be pushed firmly and squarely over the valve guide using the valve stem as guide. Do Not Force seal against top of guide. When installing the valve retainer locks, compress the spring only enough to install locks.
2. Follow the same procedure on the remaining cylinders using the firing sequence 1-2-3-4-5-6. Make sure piston is at TDC on the cylinder that the valve spring is to be removed.
3. Remove spark plug adapter tool and Special Tool MD 998772A.
4. Install rocker arm(s).
5. Install camshafts, timing chain, and timing chain cover.
6. Install cylinder head covers.
7. Install upper intake manifold.
8. Install air cleaner housing and inlet hose.
9. Connect negative cable.
OFF VEHICLE
1. If removed, install valve(s).
2. If valves or seats have been reground, check valve tip height (A) (Fig. 41). If valve tip height for intake valve is greater than 47.59 mm (1.8737 inch) or 49.14 mm (1.9347 inch) for exhaust valve, grind valve tip until within specifications. Make sure measurement is taken from cylinder head surface to the top of valve stem.
3. Install valve seat/spring seat assembly over valve guides on all valve stems (Fig. 42). Ensure that the garter spring is intact around the top of the rubber seal. Install valve springs, valve retainers.
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. 41), 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.