Alternator pully resistance to turning

Technical Area Engine, Transmission, Exhaust etc
1
  1. My model of MX-5 is: __NBFL 1.6 UK car
  2. I’m looking for technical help or recommendations on: __ alternators

Hi all

I’m assuming without a belt fitted the alternator pulley on my NBFL should rotate very freely when turned by hand?

And as it doesn’t, that my alternator is either scrap or in need of a refurb / new bearings?

To explain, the alternator belt has snapped and trying to turn the alternator pulley by hand is impossible.

Thanks in advance for any comments.

2

New alternator needed, for sure.

Make sure you get one of exactly the same type, others might look like they’ll fit but won’t charge correctly and can fry the ECU.

Heed advice from club member Rhino666, he knows exactly what’s what with these. Rob Rhind at mx5bitz.co.uk

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Thanks Richard - reply appreciated:)

4

Hi

Just dropping in on this to advise.
I assume this is the original Hitachi LR180 alternator?
If it has been left unused for a while, may be recoverable.
The bearings very rarely are the problem, it is rust to the field coils and armature that seizes these up. Provided the alternator has not cracked its case where the four steel bolts react galvanically with the aluminium case halves, swell up, crack the case and eventually take it off centre.
I would remove the alternator and check it over for cracks. I spin these up with a nut runner and 24mm socket. Once the rust is tapped out it will hopefully spin freely again.

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5

Sounds like she as not been used for a good while, this is a trait of the MK 2.5 alternators and is just oxidation/surface rust. .
They are easy to free back up before you start forking out for a new one bud.
M-m

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Thanks for the reply rhino666 -much appreciated.

It is the original Hitachi LR180 alternator - the car’s been family owned almost 20 years and nothing has ever broken before. And as guessed the car has sat in the garage over the winter unused.

I will see if I can free it off as suggested, as it would be great to reuse the existing alternator.

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Thanks for the reply M-m- also much appreciated. I’ll try and free it back up as you have suggested before thinking about a replacement. To add - I can only add one ‘solution tick’ but both you and rhino (and Richard in his reply) collectively provided the answer - many thanks.

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Dealt with it many many times buddy, shout if i can further advise .
M-m

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