Alternator nut?

[mole42]

Can anyone tell me the size of the nut securing the pulley & fan onto the alternator? And is it right-hand or left-hand thread? Mine has seized and I'll have to split it to get it off. The alternator fan has lost several blades and I need to change it - the vibration is awful!

[marshman]

Normal right hand thread.

They can be a pig to get off as they are usually done up FT to retain the pulley and put up with vibration/rotation. Use an impact gun, grip the pulley in a vice or hold with belt vee belt wrapped around the pulley. The mass of the armature usually allows the impact gun to free the nut. Not had one yet that wouldn't yield to an impact gun, but lots that would not shift with just a spanner.

I have an old spare in the garage that I can check the thread, but be aware if it is a more modern one it may be a metric thread.

[mole42]

Thanks! I'll try the impact gun. Unfortunately my big vice is in a different workshop two miles away from the garage and the Stag is my only car, so anything I do has to have an alternative plan in case the first doesn't work!

[Goldstar]

The one I just put a spanner on took a 7/8” spanner so should be 1/2” I think. Impact will sort it, you may need a screwdriver in the pulley to stop it rotating initially.

[richardthestag]

heat the nut first

[marshman]

Could be worth trying a bit of heat as RTS says, just in case someone has used threadlock on it in the past. The heat will soften it. You won't get enough heat into it to "crack" any rust or seizing - if you do you will likely damage the front bearing and even some of the internals of the alternator, use just enough to soften any potential threadlock use.

The nut on the old alternator I have (A127, might be a Magneto Marelli make) is an M18 x 1.5, 22mm spanner fits snugly. so its a metric one. A 7/8" A/F spanner is a loose fit so I would use that as a guide as to whether its metric or not.

Still think the nut will come off with an impact gun, nuts/threads of that size don't often seize on in my experience.

[mole42]

The windy did it! It only took a couple of seconds and the nut was loose. I replaced the fan and fastened it all up again - FT as before. No more vibration! Here’s a picture of the old fan:

IMG_3676.jpg

[Lingen]

Mole.
Mine lost several blades when the fan hit the screw part of the jubilee clip on the bottom hose. Make sure there is a good clearance there. I thought mine was sufficient until I demonstrated how fast a Stag can accelerate from standstill.

[mole42]

This one was damaged when the PAS pump suddenly dumped all the fluid (from the front oil seal) onto it at speed on the motorway. Not recommended to keep the blood pressure low!

[jbuckl]

The windy did it! It only took a couple of seconds and the nut was loose. I replaced the fan and fastened it all up again - FT as before. No more vibration! Here’s a picture of the old fan:

IMG_3676.jpg

Those blades tore at the tear here markings