Please refer to Engine Electrical for valve adjustment procedures.
REMOVAL & INSTALLATION
See Figure 1
On all engines, the cylinder head(s) must be removed to service the valves.
See Figures 2, 3 and 4
Remove the valve springs by first compressing them with a standard valve spring compressor and removing the valve keys. (A small magnet can be very helpful for this.) Release the compressor slowly and remove the spring washer and valve.
Check that the parts are in good condition and clean them. Test the spring pressures and compare them with the specifications given in the valve specification chart in this section. Place the valve in position, fit the valve guide seal, valve spring, upper washer and the valve collets.
Valves must be installed in the same combustion chamber from which they were removed.
See Figures 5, 6 and 7
The camshaft must be removed to gain access to the valve spring. Please refer to Camshaft Removal and Installation for detailed instructions.
Remove the valve depressors and the rubber rings. Depress the valve springs with a C-clamp type depressor and remove the valve collets, the upper valve seat, the spring, the lower valve seat and the valve. Remove the valve stem seals from the intake valve guides. On B234 engines, remove the lower spring collars.
On B230 and B234 engines, remove the tappets (valve depressors) and keep them in order. During reassembly, they should be returned to the same location; they are not interchangeable.
To assemble, install new valve seals (intake valves only) and install the valve and spring assemblies in the reverse order of removal.B27, B28 and B280 Engines
To gain access to the valves, the camshaft(s) must be removed from the head(s). Please refer to Camshaft Removal and Installation for detailed instructions.
To remove the valves, depress the valve spring with a valve spring compressor and remove the collets with a small magnet or similar tool. Release the tension on the spring compressor and remove the valve spring, its parts and the valve. Remove the valve guide seals.
To assemble, install new valve guide seals, being careful not to rip them when installing. After lapping the valves, assemble the valve spring parts in the reverse order of removal.Diesel Engines
The camshaft must be removed. Please refer to Camshaft Removal and Installation for detailed instructions.
Remove the valve depressors and using a suitable spring compressor, compress the springs and remove the spring retainer collets. Release the compressor and remove the spring and valve assembly. Assemble in the reverse order. Be sure to fit new valve seals.
See Figures 8, 9 and 10
Minor pits or grooves may be removed from the valve face. However, discard any valves that are severely damaged. If the face runout cannot be corrected by refinishing or if the stem clearance exceeds specifications, the valve must be replaced. Discard any worn or damaged valve train parts.
REFACING THE VALVES
See Figure 11
Using a valve grinder, resurface the valves according to specifications given earlier in this section.
Valve face angle is not always identical to valve seat angle.
A minimum margin of 1 / 32 in (0.8mm). should remain after grinding the valve. The valve stem top should also be squared and resurfaced by placing the stem in the V-block of the grinder, and turning it while pressing lightly against the grinding wheel.
LAPPING THE VALVES
Before deciding to lap the valves, consult a reputable machine shop to determine if lapping is necessary. Some machine shops will perform this for you as part of the service, but the precision machining which is available today often makes lapping unnecessary. Additionally, the hardened valves/seats used in modern automobiles may make lapping difficult or impossible.
Invert the cylinder head, lightly lubricate the valve stems, and install the valves in the head as numbered. Coat valve seats with fine valve grinding compound, moisten the suction cup on the lapping tool and attach the cup to a valve head.
Rotate the tool, changing position and lifting the tool often to prevent grooving. Lap the valve until a smooth, polished seat is evident. Remove the valve and tool, and rinse away all traces of grinding compound.
CHECKING THE VALVE SPRINGS
See Figures 12 and 13
Check the valve spring for proper pressure at the specified spring lengths using a valve spring pressure tool. Weak valve springs cause poor performance; therefore, if the pressure of any spring is lower than the service limit replace the spring.
Springs should be within 5 lbs. of all other springs. Check each valve spring for squareness. Stand the spring on a flat surface next to a carpenter's square. Measure the height of the spring; rotate the spring slowly and observe the space between the top coil of the spring and the square. If the spring is out of square more than 5 / 64 in. (2mm) or the height varies (by comparison) by more than 1 / 16 in. (1.5mm), replace the spring.