Alternator fitting and serpentine belt Mini One 1.4D - MINI Cooper Forum

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post #1 of 1 (permalink) Old Jan 6th, 2014, 04:06 PM Thread Starter
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United-Kingdom Alternator fitting and serpentine belt Mini One 1.4D


I had to remove the alternator on a 2005 Mini One 1.4D (UK Model) as it was not charging the battery. I couldn't find any info online as the engine is a Toyota variant and the mini manuals do not cover this so I decided to tackle it myself. I did not want to put the bumper and radiator into service mode to do it so this is how I went about it:

1. Disconnect the battery earth/ground terminal and ensure that it is kept well clear of the battery (-). Wrap it in polythene or other insulating material as a safeguard.

2. Slacken off the bottom alternator mounting bolt. Insert the square of a inch drive socket wrench into the square slot in the casting at the top of the alternator. Apply pressure towards the front of the car to take up the serpentine belt tension and remove the alternator top mounting bolt completely. Release the pressure on the socket wrench and the belt will slacken. Remove the 2 bolts holding the alternator cast aluminium top mounting bracket connecting the alternator to the cylinder head. This will give you better access to the tension roller.

3. Note down the position and layout of the serpentine belt and that this engine variant (1.4D) does not have a self tensioning roller to tension the belt. Note the position of the tension roller height in relation to the slot at its rear mark this if possible with a white paint pen or similar. Slacken off the nut in the centre of the belt tension roller a couple of turns and slide the tension roller upwards in its slotted guide to remove any further tension from the serpentine belt. The tension roller is easily recognisable as it is attached to a slotted curved iron casting that is fixed to the engine at the back of it by two bolts (see BMC Part No 11287790878). The bolt holding the tension roller on to the casting is held captive as its head is retained in the slot so it will not turn when slackening or tightening up. Access to the nut is limited so it is necessary to use a socket fitted to a long 3/8 inch drive socket extension bar and a 3/8 inch universal joint socket piece. The socket can be placed at 90 degrees to the bar and this will give adequate clearance to slacken the nut. This tool set up could also be used to slacken off the bottom alternator mounting bolt with ease.

4. Remove the electrical plug connector from the alternator by depressing the plastic lug on the cylinder head side of the plug with a very small screwdriver and then tease the plug away from the alternator with a small screwdriver (flat blade).

5. Slide the protector rubber off the live output terminal at the back of the alternator, remove the nut and disconnect the electrical connector. This is very tricky as access is very restrictive however it is not impossible and by some judicious hand manipulation and the use of both a cranked ring spanner and a small 13mm OE spanner it can be achieved. One tip is to face away from the car and reach into the gap with your left hand. At a push and particularly if you have large hands then you could remove the top coolant hose and mounting for better access but this means that you would have to refill and bleed the coolant system afterwards.

6. Lift the serpentine belt clear of the alternator only and tie it off to one side. Support the alternator and remove the lower alternator mounting bolt completely. Lift out the alternator. It can be a bit tight on the lower mounting and may have to be rocked side to side and forward and back or levered gently to release it.

7. Take off the alternator rear cover (3 bolts). Remove the brush holder (2 screws) and check out the brushes for damage replace if necessary. For refitting, the brushes can be held back against their spring pressure by a small pin fitted through the hole at the top of the brush holder. This pin is carefully removed to release the brushes when the holder is locked back in position. In my case the brushes were ok so I took the alternator to a local specialist who advised that some of the diodes had burned out. He replaced the plate holding the diodes for a moderate charge which was considerably less than the cost of a new alternator. He also tested the alternator for serviceability and electrical output after the repair.

8. Refitting is as follows: Clean the lower alternator mounting and the corresponding fixing lugs on the alternator with some emery cloth if the alternator was tight coming out to ensure that it slides back in to place effortlessly. Refit the alternator on to its lower mounting and insert the lower mounting bolt hand tight. Refit the serpentine belt on to the alternator pulley and route it below the tension roller. Lever the tension roller downwards so that it goes back to the position that was marked prior to slackening. Ensure that the serpentine belt is routed correctly and is correctly located on all of the pulleys. Tighten up the centre nut on the tension roller. Refit the alternator plug fully home. Refit the alternator live output electrical connector, tighten it up and replace the rubber protector cover. Refit the top alternator mounting bracket to the cylinder head. Insert the inch socket wrench into the square hole on the top of the alternator and apply pressure towards the front of the car such that it tensions the serpentine belt. Insert and tighten up the alternator top mounting bolt keeping the serpentine belt under the correct tension. Tighten up the alternator lower mounting bolt.

9. Once all is reassembled carry out a final check that all is ok and attach a 19mm spanner/socket to the crankshaft mounting bolt. Manually rotate the crankshaft a few turns to ensure that the serpentine belt is running true. (Access to the bolt can be made through the gap in the r/h plastic inner wheel shield with the r/h front wheel on full l/h lock. To do this jack up the car on the r/h side and support it on an axle stands).

10. Finally lower the car and connect up the earth/ground lead (-) to the battery and tighten up. Start the engine; check the charging light goes out; check that the serpentine belt and pulleys are running true and that there is no belt slipping and check the voltage at the battery to ensure that it is charging at the correct level.

11. A new serpentine belt could be fitted as part of this job, however for the access required to do it then the car would have to be jacked up on both sides and supported on axle stands with the bottom engine protective shield removed. A two pronged serpentine belt locating tool would also be essential to locate the belt correctly around the pulleys.

Jan 2014
captainflak is offline  
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