The first part tells you how to remove and fit a like for like 50amp 12V Valeo Alternator. The second part shows you what to do if you want to fit a 70Amp alternator into a car which previously had a 50Amp. The 70Amp was fitted to some of the BX16 range towards the end of production and sometimes a srap yard or parts shop may sell you one instead of a 50Amp - despite what they may tell you - they don't fit but are close and can be made to, see below. Please excuse the quality of some of the pictures, Mrs S had the camera so I had to resort to my rubbish phone.
Tools and parts needed:
50 Amp replacement
-replacement alternator
- set of open/ring metric spanners
- set of metric sockets
- a 21mm doglegged ring spanner or a large adjustable spanner
- a pot of vaseline
- a breaker bar or similar strong lever
- a new alternator belt (may as well change it)
- a can of spray on Belt Slip (optional)
- cable ties
replacing the 50 amp with the 70 amp
in addition to the above you will need:
-70amp alternator
- several sizes of ring connectors - including large ring connectors
- heat shrink or insulation tape
-a soldering iron and solder (optional)
- a set of electrical crimpers
- a Stanley knife for cutting wires
- a wire stripper (optional)
- a 10mm bolt and nut (for adapting the pulley shield mount
-
The alternator is easily accessible in the petrol BX's – it sits at the offside front of the engine above the HS pump, You can't miss it. It is held in place with a large pin nut at the side closest to the engine and by an adjustable nut/bolt arrangement on the front side where it is bolted to the mounting plate – a 'C' plate that also mounts the HS pump at the bottom.
First task is to remove the belt shield – this stops you catching your clothes in the pulley and having your bonce clouted off the engine block as a result – it is fastened with two captive bolts:
exposed
Next step is to loosen the mounting pin – is a pig to get to you'll need a spanner – 21mm so larger than most sets it is also in a very awkward position as the proximity of the engine mount frame means you can't get a socket on it and the position of the bolts means that there is only one angle of attack for getting a straight spanner in – the ideal tool is a doglegged round spanner. I don't have one of this size (every other flippin size – so I resorted to an adjustable spanner.)
The position of the mounting pin nut:
The angle of attack with the spanner:
Once loose enough to use your fingers undo it and withdraw the pin as far back as it will go – this will free up the mount at the back of the alternator. Note that you will not be able to remove the pin completely due to the engine mount.
The mounting pin in withdrawn position
Next, remove the front tension bolt from the 'C' Mounting plate, you will need 2 spanners for this. The alternator will now move on it's axis and the belt can be removed.
Position the alternator so that it is sitting as low as it can go and then unscrew the B+ nut and remove the spade connector in the back of the voltage regulator. Don't remove these earlier as the B+ is very tricky to get to due to the position of the ignition module and a coolant hose.
The alternator can now be removed from the car – it may stick at the mounting pin so rotate the whole unit up and towards the engine and then lift it up and out towards you.
Refitting the alternator is the reverse of the above except that you fit the mounting pin before the adjuster on the 'C' Plate – don't tighten the mounting pin yet, get some tension on it so the alternator will move stiffly – then get a breaker bar – slot it between the engine block and the bottom of the alternator at the ENGINE side of the alternator – This will enable you to lever the alternator into position and hold the tension on the bolt whilst locking it into position.
Refit the belt and then lifting the alternator with your right hand and pushing down on the lever with your left get a good tight tension in the alternator belt – the belt should not deflect more than a centimeter or so when prodded firmly with a finger halfway between the alternator pulley and the crankshaft pulley.
Fit and tighten the adjustable nut when you have the appropriate tension on the belt, then, using the 21mm spanner – tighten the mounting pin nut using the angle of attack you used to undo it as above.
It might help to get a helper to keep the tension on the lever whilst you tighten the adjustable bolt.
When it is tight and in position, tighten the mounting pin bolt until tight.
Reconnect the battery and start the engine – check the voltage across the battery terminals with a multimeter - it should read in excess of 13V – 14-14.5 is a healthy.
Refitting a 70Amp alternator.
The 70 AMP Valeo alternator is ever so slightly larger than the 50 AMP one.
I has an internal Voltage Regulator
an internal fan
a wider pulley – 6 'ribs'
larger connection pins.
You will need to remove the spade connector and the B+ O ring connector which is too small for the larger alternator. Replace these with appropriate sized O rings – make sure your crimping is sound, ideally solder and wrap in heat shrink or insulation tape. A poor connection here can cause your charging system to fail – usually in the pissing rain on a February night so it is worth doing properly.
These need to be replaced with appropriate O rings
Give the O rings a good coating of Vaseline as you won't be able to reach them when attached to the alternator.
Mount the alternator on the mounting pin and hand tighten the pin. -
Attach the two wires to the alternator – the smaller one needs a 8mm socket – the larger one a 14mm socket – nb be careful not to overtighten these nuts as you can easily strip the threads – it is important to attach the wires at this stage – you won't be able to access them when the alternator is in position because of the lack of space.
Position the belt – NB if you are using the 6 rib pulley rather than changing to a 4 rib then ensure the belt sits IN THE MIDDLE of the pulley – i.e. rib belt rib – the two extra ribs are either side – this will ensure your belt is running perpendicular and won't shed itself.
You will find that the alternator is too wide and the adjustable mount is not aligned to the bolt hole on the alternator plate...get a soft headed hammer and GENTLY tap the adjustable mount towards the front of the car – checking frequently the position of the bolt hole with the mount – when aligned insert the adjustable bolt.
Use the lever method above to tension the belt, tighten the adjustable bolt and then the mounting pin nut as tight as it will go. Check the tension of the belt.
Refit the pulley cover – note that if you have a wider pulley fitted you will have to attach the cover by using a longer bolt to hold it in position to the off side side of the adjustable plate -
This picture shows how the cover is attached to the adjustable plate normally – if using a wider pulley the cover needs to be bolted here but on the OTHER side of the plate this ensures the cover will not rub on the pulley
you will be unable to attach this end of the cover as the hole will no longer align due to the slightly larger size of the alternator.
Note it is a good idea to cable tie the water hose at the rear of the alternator so it doesn't rub against the rear of the alternator
reconnect the battery, start the car and measure the voltage across the battery terminals with a multimeter, it should read 14+ Volts
It is a good idea to carry your spanners and a spare belt in case you have to re tension the alternator in the first few days. I would also carry a spare belt especially if you have fitted the larger alternator as belt wear will be greater than usual – a frequent squirt of Belt Slip spray can help here.
