99173 4 Mercury GASKET

preparatory steps: a) remove front timing gear coverb) remove valve covers1. Rotate the crankshaft clockwise (as viewed from front of engine) to top center compression stroke No. 1 piston. See LOCATING TOP CENTER COMPRESSION POSITION FOR NO. 1 PISTON in TESTING AND ADJUSTING.2. Install the timing pins in the left and right camshafts. Drain engine coolant. 3. Disconnect left aftercooler water elbow (1) from aftercooler housing. Disconnect water temperature sending unit (2). Remove oil line (3). Disconnect oil line (4).4. On Marine engines only, disconnect the turbocharger heat shield water return line from top of water temperature regulator housing. Remove right and left exhaust manifold front water outlet lines. 5. Disconnect right aftercooler water elbow (5) from housing. Remove bypass line (6). Disconnect lines (8) and (9) from lower housing.6. On Marine engines only, remove the right and left aftercooler housing sea water outlet lines.7. Attach hoist to regulator housing. Remove six lower housing-to-cylinder head bolts (7), and remove water temperature regulator housing assembly-weight 140 lbs. (64 kg).8. Remove cluster gear and thrust washer. Using tool setup (B), remove bearing from cluster gear. Remove cluster gear thrust washer from front timing gear cover.
To avoid piston and valve interference, do not rotate crankshaft with timing gears removed and camshafts installed.
9. Remove front timing gear plate retaining nuts, locks, and bolts (13). Remove front timing gear plate (14).10. Remove oil line (10). Remove the shaft retaining bolts (11). Remove the shaft and camshaft drive idler gear (12). 11. Using tool setup (A), remove the bearing from camshaft drive idler gear.Install Front Timing Gears And Plate
To avoid piston and valve interference, do not rotate crankshaft with timing gears removed and camshafts installed.
1. Using tool setup (A), install bearing in camshaft drive idler gear. Install the idler gear (1), shaft (2), retaining bolts and lock. Install the oil line.2. Install and trim the plate-to-cylinder block gasket flush with the bottom face of block. 3. Position the front timing gear plate (3) on the engine and install the bolts, nuts, and locks. 4. Using tool setup (B), install bearing in cluster gear. Install cluster gear thrust washers in the cylinder block and front timing gear cover. Install the cluster gear (4) on engine with "V" mark on gear aligned with the "V" mark on crankshaft gear (5).
Always be sure that the No. 1 piston is at top center compression stroke, and the timing pins are installed in timing slots in left and right camshafts before installing cluster gear. Damage to the engine can result if above procedure is not followed.
5. Attach a hoist to water temperature regulator housing assembly. Position regulator housing assembly (6) on engine and install six retaining bolts. Connect the two water lines to lower housing. Connect right aftercooler water elbow. Install the water bypass line.6. On Marine engines only, install the exhaust manifold front water outlet lines. Install the aftercooler housing sea water outlet lines.7. Connect left aftercooler water elbow. Connect water temperature sending unit. Install the top oil temperature oil line. Connect bottom oil line to sensing unit.8. On Marine engines only, connect the turbocharger heat shield water return line to the top of water temperature regulator housing.9. Remove all timing pins from their timing slots. Install timing pins in their respective storage positions. Install engine coolant.concluding steps: a) install valve coversb) install front timing gear cover