Coolant pump - removal, overhaul and refitting

Cooling and heating systems / Coolant pump - removal, overhaul and refitting

Note: The design of the pump differs between the 903 cc and the other two engines, but the removal, overhaul and refitting operations are essentially similar.

1 To gain access to the coolant pump, open the bonnet and remove the air cleaner.

2 Slacken the alternator pivot and adjustment nuts, push the alternator in towards the engine and slip the drivebelt from the coolant pump pulley. Unplug and remove the alternator.

3 Drain the cooling system as previously described.

4 Disconnect the hoses from the coolant pump, also the metal coolant transfer pipe (photo).

9.4 Coolant distribution tube at rear of pump

5 Unscrew and remove the coolant pump securing bolts, and lift the pump from the engine. Peel away and discard the old gasket.

6 Clean away external dirt.

7 The pump is likely to need overhaul for worn or noisy bearings, or if the gland is leaking. There is a drain hole between the gland and the bearings to prevent contamination of the bearing grease by leaks, and possible damage to the bearings. Gland leaks are usually worse when the engine is not running. Once started, a leak is likely to get worse quickly, so should be dealt with soon.

Worn bearings are likely to be noted first due to noise. To check them, the pulley should be rocked firmly, when any free movement can be felt despite the belt. But if the bearings are noisy, yet there is not apparently any free play, then the belt should be removed so the pump can be rotated by hand to check the smoothness of the bearings.

8 Dismantling and assembly of the pump requires the use of a press, and it is preferable to fit a new pump.

9 For those having the necessary facilities, overhaul can be carried out as follows.

10 Remove the retaining nuts and separate the two halves of the pump.

11 The pump shaft is an interference fit in the impeller, bearings, and pulley boss. How the pump is dismantled depends on whether only the gland needs renewing or the bearings as well, and what puller or press is available to get everything apart.

12 Assuming complete dismantling is required, proceed as follows. Supporting it close in at the boss, press the shaft out of the pulley. Pull the impeller off the other end of the shaft.

13 Take out the bearing stop screw.

14 From the impeller end, press the shaft with the bearings out of the cover half of the housing.

15 Press the shaft out of the bearings, take off the spacer, the circlip, and the shouldered ring.

16 Do not immerse the bearings in cleaning fluid. They are “sealed”. Liquid will get in, but a thorough clean will be impracticable, and it will be impossible to get new grease in.

17 Check all the parts, get a new gland, two new grommets, (1116 cc and 1301 cc) and a new gasket. Scrape all deposits out of the housing and off the impeller.

18 To reassemble, start by inserting the new grommets (1116 cc and 1301 cc) in the grooves by each bearing. Fit the circlip to the shaft, then the shouldered ring, bearings and spacer. Fit the shaft and bearing assembly into the cover. Fit the stop screw. Press on the pulley.

19 Fit the new gland (seal), seating it in its location in the cover. Press the impeller onto the shaft. The impeller must be put on part way, and then the housing held in place to see how far the impeller must go down the shaft to give the correct clearance, which is 0.8 to 1.3 mm (0.03 to 0.05 in) as shown in Figs. 2.4 and 2.5.

20 The impeller clearance can be checked through the coolant passage in the side of the pump.

21 Refitting is a reversal of the removal process, but use a new flange gasket and tension the drivebelt as described in Section 8 (photo).

9.21 Fitting coolant pump (1116 cc engine)

22 Refill the cooling system.

Fig. 2.4 Sectional view of 903 cc engine coolant pump (Sec 9)

1 Pump body
2 Pump cover
3 Impeller
4 Connector for hose from outlet to pump 5 Seal
6 Gasket
7 Circlip
8 Bearing shoulder washer 9 Inner seal
10 Inner bearing
11 Bearing retainment screw and lock washer 12 Spacer
13 Outer seal
14 Outer bearing
15 Lock washer
16 Pulley
17 Pump shaft

Fig. 2.5 Sectional views of 1116 cc and 1301 cc engine coolant pump (Sec 9)

Fig. 2.6 Checking impeller clearance (Sec 9)