What is this in the photo?

[Altonx]

What is this circled in the photo, AC2W engine?
I've seen alternators wired to this, is it for an ammeter?

[cobbadog]

To me it looks like an oil pressure switch or engine temp sender

[Altonx]

Not sure cobbadog, like I said I've seen alternators wired directly to this sensor which made me guess its for an ammeter but also tachometers (rev counters) are wired from the Alternator sometimes

[dkmc]

I'll wager 20 Attaboy's it's oil pressure sensor or safety switch.

[cobbadog]

I would unscrew it to see whats in there but I feel it is a pressure switch.

[Diesel Engineering]

It is basically an oil operated switch. Your engine appears to be an AC2W marine engine. This switch was used to energise the charge alternator whenever the engine was started.

[Altonx]

It is basically an oil operated switch. Your engine appears to be an AC2W marine engine. This switch was used to energise the charge alternator whenever the engine was started.

Top man, Thank you