Contents: Six-cylinder engine ↡ Eight-cylinder engine ↡
Six-cylinder engine
Drain the coolant (section 5.1.1).
Remove the radiator (section 5.2.2).
Remove the fan with the clutch.
Loosen the belt tension and loosen the pulley mounting bolts, holding the pulley from turning, as shown in Fig. 111.
Fig. 111. Removing the coolant pump pulley of a six-cylinder engine. The screwdriver is placed between the heads of the two mounting bolts.
Remove the damper by unscrewing the six Allen-head mounting bolts.
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Loosen the mounting bolts and remove the coolant pump. Clean the separating surface on the cylinder block.
When reusing the pump, thoroughly clean the split surface. Install a new gasket and a new O-ring. Install the pump in the reverse order. Tighten the alternator drive belts and coolant pump as described below.
Eight-cylinder engine
The pumps of both types of engines have changed over time, without changing their operating principle. Fig. 112 shows the coolant pump of an eight-cylinder engine.
Fig. 112. Coolant pump and thermostat for M 116/117 engines.
1 - housing cover,
2 - sealing ring,
3 - thermostat.
Drain the coolant. Loosen the coolant pump drive belts and the power steering pump.
Loosen the clamps and remove the coolant hose from the pump.
Remove the spring clips securing the fan shroud, lift the shroud and place it on the fan.
Remove the ignition distributor.
In early production engines, unscrew the ignition distributor mounting studs (using two nuts).
If the temperature gauge sensor is screwed into the intake manifold, disconnect the wire, also disconnect the wires from the fan electromagnetic clutch switch. Remove the front hose clamp, unscrew the mounting bolts and remove the intake manifold with the gasket and spacer.
Remove the damper.
In Fig. 113 the arrows show the mounting bolts, unscrew the bolts and remove the coolant pump. Thoroughly clean the separating surfaces of the pump and cylinder block and install the pump in the reverse order. Check the ignition timing and adjust if necessary. Tighten the mounting bolts of the viscous fan clutch to 25 Nm.
Fig. 113. The arrows show the bolts securing the coolant pump of an eight-cylinder engine.
If the pump is damaged, it must be replaced as a whole. To replace the pump seal, you will need a puller to remove the impeller of an eight-cylinder engine and a press to press out the impeller of a six-cylinder engine. It is better to contact a service station to perform this work.