I don't know if this should be asked in "Electric" or "Engine" topic but I'll try here...

 

I have 2 engines (MH 1.3 55hp carb), one is from a mk2 (1991-03) and the other from a mk2f (1992-03). I'm a bit confused in matching the model of the alternator pulley (aka v-belt pulley) and alternator/generator (didn't notice the alternators references but I will). I have no clue if the previous owners used the right alternator model. How do I choose the pulley depending on the alternator I have or want to use ?

 

The mk2f v-belt pulley has a reference of VW 030 105 255E with an outer diameter of approx. 149mm. This reference is expected for the mk2f, so far so good.

The mk2f v-belt pulley has no visible reference and has an outer diameter of approx. 136mm. I don't know if that's the diameter expected on the mk2.

 

Obviously, I may simply use the pulley and alternator which were on the car. But what if the alternator was not meant for the pulley diameter (running too fast / too slow) ?

According to this topic here : 90A alternator onto mk2/2f

There's no mention about the pulley diameter. Does this means I can use these different pulley interchangeably ?

 

Below are the pulley I mentionned previously (left is mk2f, right is mk2):

Edited 22 November, 20214 yr by cedreex

I did not know aux pulley wheel was different size, just that tensioning method changed for alternator, and used a toothed cog bolt on a toothed bar.

 

You may need a 710 mm belt (mk2f) or 690mm belt (mk2) from memory.

 

On the alternator I think tiny 56mm alternator pulley was used until October 1983, then 71mm used.

 

It's all about the ratio pulley to pulley and belt contact area to transfer power.

Edited 22 November, 20214 yr by dvderlm

2 hours ago, dvderlm said:

I did not know aux pulley wheel was different size, just that tensioning method changed for alternator, and used a toothed cog bolt on a toothed bar.

 

You may need a 710 mm belt (mk2f) or 690mm belt (mk2) from memory.

 

On the alternator I think tiny 56mm alternator pulley was used until October 1983, then 71mm used.

 

It's all about the ratio pulley to pulley and belt contact area to transfer power.

 

According to partsouq parts catalog, I should use a 675x10 belt (F ..-E-000 001>>;;F >> 80-MW162 419). I think such belt makes sense because the pulley is smaller. I've use a 695mm (not sure I remember, could have been 675) on this car before stopping the car for about 2 years now.

My worry is if my alternator run too slow with such pulley I may encounter charging problem when idling (I really don't know). Though I haven't check my alternator model and its pulley yet (it's stored somewhere but I'll do it). Then I'll check for 71mm pulley since my polo is of March 1991

Edited 22 November, 20214 yr by cedreex

Alternator self activation is about 400rpm, usually.

The bearings inside are probably good for 12 to 15,000rpm _ depends on cooling design.

 

3 hours ago, dvderlm said:

Alternator self activation is about 400rpm, usually.

The bearings inside are probably good for 12 to 15,000rpm _ depends on cooling design.

 

 

Very useful information. Thanks