1989 245 Auto trans (US)
What is this threaded hole for?
It's on the PS just below the coolant drain (brass fitting).
Have a link below to older thread, with pics, where a user asks about the sensor that is in his and no one had an answer about the hole or the sensor.
Should I plug this with something?
Found this 245 that had been sitting for years, but still running, to be a project for my oldest son to do with his oldest son(13) for a first car. His Dad built a '68 Mustang from the ground up with me for his first car. Trying to encourage the tradition of wrenching. His Dad used to have a 245 that he wished he had not sold years ago. Also, we brought that son of our home from the hospital in our 145 after his birth.
Things area currently apart to fix the freeze plug in the head that had a huge hole in it.
TIA

https://volvoforums.com/forum/volvo-...il-leak-91789/

 

There was a sensor installed when the engine was built - no wiring was ever connected to the thousands i've seen (over a 35 year period) - so nothing goes there. Someone told me once it had to do with verifying the timing at the factory - but note the timing is not adjustable.

 

See discussion in the Volvo Green Manuals.