Camshaft: Service and Repair
Removal and Installation of Camshafts1. Remove the valve cover.
Flywheel Timing Marks-Bellhousing Removed:
2. Set the engine to TDC by rotating the crankshaft in normal engine rotation until the "0" mark on the flywheel is aligned with the timing mark on the end plate.
Camshaft Timimg Mark Aligned With Mark On Camshaft Bearing Cap:
Note: Check also that the marks on the camshafts are aligned with their matching marks on the bearing caps. If the marks are not aligned, turn the engine over an additional 360° (1 revolution).
Caution: If the camshaft timing marks shown be are not exactly aligned, the timing chain or one of the sprockets may be severely worn or the timing chain may have jumped out of position. See Timing Chain for additional information.
3. Remove the ignition distributor.
Oil Supply Pipes For Hydraulic Cam Followers Being Removed On Mid 1988 And Earlier Cars:
4. Remove the external oil supply pipes from the cylinder head, if applicable.
Caution: Do not twist the pipes when removing them. This may damage the sealing surfaces between the pipes and the fittings.
Note: Beginning in mid-1988, a new cylinder head was used and the external oil supply pipes were discontinued.
Camshaft Timing Chain Tensioner Being Removed:
5. Working from the side of the cylinder head, remove the camshaft timing chain tensioner.
6. Carefully unbolt the camshaft bearing caps evenly until all valve spring pressure is relieved. Remove the camshaft by lifting the chain off the sprocket.
Caution: Do not rotate the engine if the camshaft timing chain is removed from either camshaft. The pistons can hit the valves and damage them.
Note: If removing both camshafts, insert a stiff wire through the chain to prevent it from falling into the timing chain cover area.
Installation is the reverse of removal. If removed, be sure to refit the hydraulic cam followers in their original positions. Make sure the flywheel is set at the TDC mark. Install the camshafts such that the timing marks are correctly aligned before tightening the camshaft bearing caps. When installing the camshaft bearing caps, make sure all numbers on the caps align with their numbers on the cylinder head, if applicable. Install the black camshaft bearing cap bolts on the spark plug side of the cap. Make sure the oil spray bar is correctly aligned with the bar's fittings.
Special Black Camshaft Bearing Cap Bolts Must Be Installed On Spark Plug Side Of Cap:
Caution: The black camshaft bearing cap bolts are drilled to provide oil passages to the hydraulic cam followers and must always be installed on the spark plug side of the cap.
Note: Bearing caps marked with numbers 1 through 5 are used on the intake camshaft and 6 through 10 are used on the exhaust camshaft.
Make sure all of the timing chain slack is on the tensioner side of the chain and install the chain tensioner. Turn the engine over several revolutions in the direction of normal rotation and bring back to TDC. Double check all timing marks. It necessary, remove the tensioner and reposition the chain on the sprockets. Install the valve cover using new gaskets and sealer. Install the distributor and ignition wires.
Caution: Correct camshaft timing is critical. If the timing chain is off by as little as two teeth on the sprocket, the pistons can contact the valves. Always check and recheck camshaft timing by turning the engine over by hand.
Tightening Torques:
Camshaft bearing caps to cylinder head 15 Nm (11 ft-lb)
Camshaft timing chain tensioner to timing case 63 Nm (46 ft-lb)
Valve cover to cylinder head 15 Nm (11 ft-lb)