I bought an oil pressure test kit that came with 10 different adapters. Metric adapters included M10 x 1, M12 x 1.5, M14 x 1.5, M16 x 1.5, M18 x 1.5.

Volvo is apparently the only manufacturer to use an oil pressure sensing switch with M13 X 1.5 threads.

I scoured the web trying to find an adapter. The closest I could find was a brake line adapter that is for flared fittings and had 13MM thread pitch, but was a 3/8 X 24 flare fitting female. I have no 3/8 X 24 adapter and a flare fitting would leak in this application anyway.

Any ideas of where to find a proper adapter or a different place on the engine to screw in the tester that uses a more common thread pitch?

Peter,
What kind of engine and what year?
--
Keeping it running is better than buying new

Upon closer inspection, it looks like the oil pressure sender is M12 X 1.5. It just seemed like M13 because the M12 X 1.5 fitting for the oil pressure test gauge seemed loose when I took out the Volvo sender. But it was loose because the sender took the threads with it when it came out.

I still have to figure out how I'm going to put an insert in. Remove the intermediate sump piece or try to drill and tap it in place?

Waiting for Klaus' wisdom.

I have no 'wisdom' regarding your dilemma. I would remove the radiator to get a good 90 degree access and then helicoil the stripped threads, much better than tearing the engine apart. Remember, you are dealing with 'soft' aluminum, so use anti-seize when inserting the new sender and do not over torque.

--
Keeping it running is better than buying new

I spoke with TimeSert tech support. Their kit comes with a drill bit that has a square that fits a tap handle. So, they agreed that I could use a 3/8 drive Lisle tap socket and my right angle 3/8 drive air ratchet to do the drilling and tapping in the 11 inch space I have available. I will also use thread sealant on the outer threads of the insert.

The biggest challenge will be determining when the drill is positioned straight, because, while you can see if it is off left to right, when viewed from the top, it hard to see if it is square to the hole on the up and down axis.

Pulling the intermediate sump would make it easier, but I worry that the crank, which would be supported by the timing belt in the front and the transmission input shaft in the rear, would damage the front or rear seals, overstress the timing belt, or possibly the distort the clutch plate.

Hopefully I can do it in place.

The car is a 99 V70T5.

Since I decided I have to drop the sump and replace the o-rings, I went ahead and reinstalled the oil pressure sender. Somehow I managed to strip the hole. This goes into the aluminum intermediate sump section.

Since the oil pan will be off, is it possible to drop the intermediate sump section with the engine in the car? The piece holds the lower main bearings, so if it is removed, what would support the crankshaft?

Or is it better to remove the radiator and drill / tap / install an insert with the intermediate section in place? Because M13 X 1.5 is such an oddball size, it looks like the only choice for an insert is the $120 TimeSert 1315 kit. Helicoild doesn't make that size.

Based upon his other post (Frothy oil), he's working with a 1999 V70 T5M.