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Alternator fan

PostPosted: Sun Jul 31, 2016 7:51 am
by jimH
I recently purchased a replacement 4023-S alternator that will be mounted on a Yanmar 4JH3. It is mounted in reverse orientation to the normal Yanmar alternator and in an area with limited air circulation. I have seen reference in posts to a special cooling fan for alternators with this mounting. Does the standard alternator come with this or can I buy one?

Re: Alternator fan

PostPosted: Sun Jul 31, 2016 1:54 pm
by Coulomb
The alternator comes with a standard uni-directional fan, designed to rotate in the normal direction. The standard fan has blades that are slanted in one direction. It will not run long mounted as you plan, maybe 10 minutes before the smoke gets out.

You need the bi-directional fan with blades that are oriented axial to the shaft.

You can order that from Ruth.

Re: Alternator fan

PostPosted: Sun Jul 31, 2016 5:09 pm
by jimH
Can you see if this is a bi-directional fan? It is on the alternator I removed.

Re: Alternator fan

PostPosted: Sun Jul 31, 2016 7:58 pm
by Coulomb
Yes, that is a bi-directional fan.

Re: Alternator fan

PostPosted: Mon Aug 01, 2016 5:59 am
by jimH
Thanks
Is the nut holding the fan in place a normal thread or reverse pitch?
And a question. Why sell an alternator with a fan that only works in one direction when you have a fan that works in both directions?

Re: Alternator fan

PostPosted: Mon Aug 01, 2016 11:46 am
by Coulomb
The nut is normal RH thread.

A bidirectional fan is 10-15% less efficient and not required in most applications.

Re: Alternator fan

PostPosted: Mon Jul 31, 2017 11:14 am
by jimH
Has anyone had problems with the pulley nut spinning off a reverse mounted alternator?

Re: Alternator fan

PostPosted: Wed Aug 23, 2017 8:23 pm
by ggray
Jim, when you say reverse mounted, do you meant it is turned around and it is facing the opposite direction? That the pulley ends are facing each other?