Volvo Alternator - Nut Size for Tacho?

[Trident]

On the KAD and Penta etc Volvo engines they all use one standard alternator which has a tiny threaded terminal for the rev counter wire (W terminal)

I've lost the nut for this terminal and its a tiny thread - the internet tells me its M5 but the M5 nuts I have are too big - any ideas on size please?

 

[Alex_Blackwood]

On the KAD and Penta etc Volvo engines they all use one standard alternator which has a tiny threaded terminal for the rev counter wire (W terminal)

I've lost the nut for this terminal and its a tiny thread - the internet tells me its M5 but the M5 nuts I have are too big - any ideas on size please?

Possibly BA either 2 or 3?
BA Screw Fixings

 

[VicS]

On the KAD and Penta etc Volvo engines they all use one standard alternator which has a tiny threaded terminal for the rev counter wire (W terminal)

I've lost the nut for this terminal and its a tiny thread - the internet tells me its M5 but the M5 nuts I have are too big - any ideas on size please?

M4 I think you will find

From the parts list:

 

[Trident]

Thank you