The new oil pressure sender arrived from eBay (a few days late), but it only cost $16.66 so I can’t really complain.
The issue was the nib from the sender unit had broken away and was stuck in the wiring as can be seen below.
Installing the new sender is a simple matter of unscrewing the old sender unit from the block, screwing in the new sender unit and attaching the wiring connector to the end of the sender.
The nib stuck in the wiring.
Here’s the nib after being removed.
The new sender beside the old one.
The oil pressure light is working again.
