Do alternator fans differ in performance?

[Karlsenkystfiske]

Changing the alternator on a John Deere 4045 today. The new one should be indentical. Only more copper on windings, making it able to output 108A versus 65A on the stock one. Dealer fitted the new one with a Java Sea external regulator, to avoid the thing from burning up when I complete my LP battery bank which it will have to charge from time to time. Having put everything in place, I see(first I heard it) that there is a misalignment between the serpentine belt pulleys. Turns out thew alternator pulley is now recessed 2,5mm due to the old fan having a integrated shim that I failed to pay attention to when moving the pulley.

I now have the options to either put the old fan on the new alternator, or use new fan, and a washer. Does it matter what I do? How bad would it be to just leave it misaligned? The nearest pulley is 25cm away, edge to edge.

The two placed aside

Old fan. Dirty, but all intact.

The reason behind current misalignment




Distance between pulleys.

 

[Plum]

Changing the alternator on a John Deere 4045 today. The new one should be indentical. Only more copper on windings, making it able to output 108A versus 65A on the stock one. Dealer fitted the new one with a Java Sea external regulator, to avoid the thing from burning up when I complete my LP battery bank which it will have to charge from time to time. Having put everything in place, I see(first I heard it) that there is a misalignment between the serpentine belt pulleys. Turns out thew alternator pulley is now recessed 2,5mm due to the old fan having a integrated shim that I failed to pay attention to when moving the pulley.

I now have the options to either put the old fan on the new alternator, or use new fan, and a washer. Does it matter what I do? How bad would it be to just leave it misaligned? The nearest pulley is 25cm away, edge to edge.

The two placed aside

Old fan. Dirty, but all intact.

The reason behind current misalignment


Distance between pulleys.

If it were mine I not accept that misalignment, I would shim the pulley to get it as close to perfect as I could measure. I would also use the cooling fan provided with the new alternator.

Www.solocoastalsailing.co.uk

 

[Refueler]

If it were mine I not accept that misalignment, I would shim the pulley to get it as close to perfect as I could measure. I would also use the cooling fan provided with the new alternator.

Www.solocoastalsailing.co.uk

I just paid out a large wedge of money on my Range Rover because German Dealer who sold it had changed belt / pulleys and had 2mm misalignment on front belt on my 4.4l TDV8 ..... so I would get that aligned PDQ !! You really do not want to know how much it cost to put right .... it damaged not only the new belt - but also the alternator ...

2 bl***y mm !!

 

[Karlsenkystfiske]

After talking to the vendor of the new alternator we decided it would be no problem moving over the fan from the old unit. Seems to work like a charm. No noise, charges very well!
Think i will clean and change brushes on the old one, keep it as a spare perhaps. It has only done 5400 hours, mostly running on idle speeds so there should be plenty left within it.

New alt, old fan.

 

[Birdseye]

in generating 105A rather than 65A, the new alternator will produce proportionally more heat. It will require more cooling to prevent burning out, assuming the batteries ( which are almost always the factor limiting current output) allow the alternator to get to 105A.

 

[ean_p]

Changing the alternator on a John Deere 4045 today. The new one should be indentical. Only more copper on windings, making it able to output 108A versus 65A on the stock one. Dealer fitted the new one with a Java Sea external regulator, to avoid the thing from burning up when I complete my LP battery bank which it will have to charge from time to time. Having put everything in place, I see(first I heard it) that there is a misalignment between the serpentine belt pulleys. Turns out thew alternator pulley is now recessed 2,5mm due to the old fan having a integrated shim that I failed to pay attention to when moving the pulley.

I now have the options to either put the old fan on the new alternator, or use new fan, and a washer. Does it matter what I do? How bad would it be to just leave it misaligned? The nearest pulley is 25cm away, edge to edge.

The two placed aside
View attachment 158833
Old fan. Dirty, but all intact.
View attachment 158832
The reason behind current misalignment
View attachment 158835

View attachment 158834

Distance between pulleys.

Are you making the assumption that the absence of the washer means that the alternator pully is now misaligned by the thickness of the washer? If so this is not necessarily true. You need to measure the two pulleys referenced to themselves or perhaps more simply referenced to the mounting face of the alternator as that is a fixed point that was common to both alternators and also to the crank pulley. Of course referencing the new pulley to the alternator mounting face only ensures that the pulley is back in the position it was in prior to the change and not that it was aligned correctly in the first place.