Withdrawal
Disconnect the ground wire from the battery.
Drain the coolant from the engine (see section «Coolant replacement»).
Remove fan.
Loosen the belt pulley bolts. While doing this, hold and press the V-belt so that the pulley does not turn.
Remove V-belt (see section «Removal and installation, alternator V-belt tension»).
Unscrew the 4 bolts securing the belt pulley and remove the belt pulley from the hub.
Six-cylinder engine: Unscrew engine lifting eye.
Pull up the toothed belt cover, having previously retracted the rubber seal.
Compress the tension spring of the toothed belt tensioner and clamp the tensioning pin with BMW tool 115010.
Loosen and push back the hose clamps. Disconnect water hoses from pump.
Loosen the fixing screws (arrows) and remove the water pump.
Four-cylinder engine: unscrew the 6 bolts securing the water pump.
Installation
Completely remove seal residues with a scraper.
Install the water pump with a new gasket and tighten the bolt evenly to 22 Nm. Tightening torque on models 316i from September 1988 and 318i from September 1987: 9 Nm. Replace O-ring.
Loosen the tensioning pin of the toothed belt tensioner, while ensuring that the water pump rotates freely.
Insert the toothed belt guard, then the rubber seal.
Screw on the engine lifting eye.
Connect water hoses and secure with clamps.
Install the belt pulley.
Install and tighten V-belt (see section «Removal and installation, alternator V-belt tension»).
Tighten the belt pulley mounting bolts to a tightening torque of 9 Nm while preventing the pulley from turning with the V-belt.
Install fan.
Attention: The fastening nut has a left-hand thread.
Pour coolant into the engine (see section «Coolant replacement»).
Connect ground wire to battery.
Warm up the engine and check the tightness of the hose connections, as well as the water pump.