S

slinky

New Member
In the process of changing my alternator for a new one off ebay and I only noticed the pulley on the new unit is smaller than the one being replaced.

Can I use it with the smaller pulley or do I need to change it.
I think I will need to change it from what I've been reading but thought I should make sure.

Thanks
Aaron
 
unless the belt won't fit and tension, then it should improve charging at idle -faster turning over
 
slinky said:
In the process of changing my alternator for a new one off ebay and I only noticed the pulley on the new unit is smaller than the one being replaced.

Can I use it with the smaller pulley or do I need to change it.
I think I will need to change it from what I've been reading but thought I should make sure.

Thanks
Aaron
Click to expand...

I suppose that's a V8 then.....(coz the Td5's alternator goes together with the vacuum pump)

Read the caracteristics on the two alternators, V/rpm ...etc, if they are the same just swap the puleys........if they are different u have o try to fit it with the belt tensioner coz using a bigger pulley on the new one it might not generate enough voltage.
.
 
sierrafery said:
I suppose that's a V8 then.....(coz the Td5's alternator goes together with the vacuum pump)

Read the caracteristics on the two alternators, V/rpm ...etc, if they are the same just swap the puleys........if they are different u have o try to fit it with the belt tensioner coz using a bigger pulley on the new one it might not generate enough voltage.
.
Click to expand...

No its a 300tdi, I meant to put that in original post.

Just tried fitting it as is and the belt is no where near tight.

The advert for the alternator does say "Please note you may need to fit the pulley from the old alternator"

I guess I hoped it would have the right one.
 
slinky said:
No its a 300tdi, I meant to put that in original post.

Just tried fitting it as is and the belt is no where near tight.

The advert for the alternator does say "Please note you may need to fit the pulley from the old alternator"

I guess I hoped it would have the right one.
Click to expand...


be glad u didnt succeed to fit it then........ smaller pulley = bigger voltage.....could have f***ed up the whole charging system
 
It would also have fecked with the tachometer ...
 
around 1994/5 they changed the size of the pulley to give better charging when the car was being used at low revs, offroad for instance. Both alternators will have the same max output but there are different size belts to go with each pully size.
I did the opposite on my 300tdi, went from a small pully to a big pully, had to change the belt for the right size as well but it worked perfectly but It does put your tacho out by about 150-200rpm
 
sierrafery said:
be glad u didnt succeed to fit it then........ smaller pulley = bigger voltage.....could have f***ed up the whole charging system
Click to expand...


Not quite true, its an alternator (with regulator) and it copes with different engine speeds fine, so it would have coped with a slightly different size pulley no worries.
 
paul_c said:
Not quite true, its an alternator (with regulator) and it copes with different engine speeds fine, so it would have coped with a slightly different size pulley no worries.
Click to expand...

Which would have been fine had the belt not been slack.

Anyway its all fixed now, rev counter working and battery light has gone out :D
Must be the easiest motor to change an alternator on ever.
 
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