Not too sure how an oil pressure sender works, but the fact that they have a large rear case means there must be something other than a variable resistor in them.

Question is, I have a small hole in mine (after being clamped into a vice)......is there any reason why it still wont work (the internals will not have been damaged, but wondering if the case holds vacuum or positive pressure)...

shoud be ok, try it with a compressor or footpump to be sure.

good idea.....I will give it a try.

A quick google shows there is a diaphragm with a small arm that moves across a resistor.

Can you not solder up the hole or buy a new one? Surely the price of a sender is very much less than an engine rebuild and much simpler to replace too?

My concern would be if the diapragm failed, surely the sender would will indicate pressure whilst at the same time oil is being lost?

The hole means there is no fixed volume of air to buffer the diaphragm so i reckon it will fail sooner than a sender which has no hole..