20-215 Notes regarding coolant pump
General
The coolant pump located at the bottom right of the engine is attached to a light alloy housing bolted to the crankcase. The coolant thermostat (318) is likewise contained in this housing.
A flange (302) is pressed onto the coolant pump shaft (303) for attaching the belt pulley. The deformation space (E) is located between coolant pump bearing (304) and cassette seal (305). The fan is attached at the stub end (arrow).
301 Coolant pump housing
302 Flange
303 Coolant pump shaft
304 Coolant pump bearing
305 Cassette seal
306 Impeller
307 Gasket
308 Hexagon bolt
M 635
316 Fit pin
317 Light alloy housing
318 Coolant thermostat
319 Gasket
320 Inlet connection
B Inlet connection to radiator
C Pump chamber
D Inlet from crankcase
E Deformation space
P20-0090-35
Engine 601
Arrangement of magnetic fan coupling and coolant pump
301 Coolant pump housing
302 Flange
303 Coolant pump shaft
304 Coolant pump bearing
305 Cassette seal
306 Impeller
309 Tensioning disc
340 Collar bolt
341 Washer
343 Ball bearing
344 Fan
344a Armature
344b Leaf spring
345 Hexagon bolt M 612
346 Belt pulley
347 Magnet body
348 Magnet carrier
349 Hexagon nut
P20-0089-15
Engines 601 (only in model 124), 602 and 603
Arrangement of viscous fan coupling and coolant pump
5 Ball bearing
295 Fan
296 3 bolts M 614
297 Hexagon socket screw M 1040
298 Viscous fan coupling
301 Coolant pump housing
345 4 hexagon bolts M 612
346 Belt pulley
P20-0098-15
Engine 601 in model 202
On this engine the viscous fan coupling is bolted onto the coolant pump mount by a union nut with left-hand thread.
Engine 601 in model 202
Arrangement of viscous fan coupling
and coolant pump
1 Viscous fan coupling
2 Fan
3 Bolt+washer, 10 Nm
4 Ball bearing
5 Union nut, waf 36 mm
Left-hand thread, 45 Nm
6 Flange
7 Belt pulley, dia. 168 mm
8 Hexagon bolt+washer M610, 10 Nm
11 Coolant pump housing
12 Coolant pump ball bearing
P20-5267-17
Coolant pump with drainage pipe
Since 01/92 coolant pumps with a drainage pipe (1) have been installed. This channels off any coolant which may flow out occasionally from the vent hole in the coolant pump housing. This thus eliminates any residue smears in the directly visible area.
The coolant pump should only be replaced if coolant is found in the expansion tank as result of a leak in the coolant pump.
Coolant pumps for installation of drainage pipes are supplied through the parts sector. When installing, always install or replace the drainage pipe at the same time.
The drainage pipe can also be retrofitted. See Programmed Repairs for operation instructions.
P20-5371-15
The coolant pump of engines 602, 603 as of start of production, of 601 in model 124 as of 02/92, is strengthened at the coolant pump housing (301) and at the coolant pump bearing (304) because of the heavier viscous fan coupling.
The diameter of the impeller (306) on all the engines is identical.
The coolant pump shaft has a tapped hole
M1022 at the front for attaching the viscous fan coupling.
From 06/89 up to 11/88 a plastic impeller was fitted to engines 601.911/912.
301 Coolant pump housing
302 Flange
303 Coolant pump shaft
304 Coolant pump bearing
305 Cassette seal
306 Impeller
316 Fit sleeve
E Deformation space
P20-0096-13
Engine 603.971
Since 09/95 a coolant pump with a larger impeller has been installed in this engine. This increases the volume flow in the cooling system.
Previous impeller 68 mm
Present impeller 72 mm