After all this time I'm literally filling up the coolant so I can finally start it since August with all the repairs I've done. You can almost call this a kind of a semi restoration rather than just a repairand I was tightening a damn bolt for the temperature sender unit and... What are the consequences and what solutions do I have?


Please tell me I can just take a cork from a champagne bottle and throw it in there, call it a day. Considering that it's carbureted and there's like 12 different ways of sensing the coolant temperature and yet only one indicator on my dash gate I don't know.

 

The stock temp sender is 1/8" BSPT aka 1/8" British Straight Pipe Thread.

Straight threads are not self sealing and require an o-ring, and a flat surface to seal the o-ring against.
This means that your sender will not seal as it currently stands.

1/8" BSPT = 9.728mm dia and 28 tpi. It uses an 8.4mm drill
1/8" NPT ≈ 10.287mm and 27 tpi. It uses an 8.6mm drill and has about a 1.5 degree taper.

This means that 1/8" BSPT is a hair smaller than 1/8 NPT and the thread pitch is very close.

Earl's has a 'Male 1/8" NPT to Female 1/8 BSPT' straight adapter available for under $20.

Grab an 1/8" NPT tap, carefully start it in the remaining threads and start cutting.
Take your time and check the fit often. It's a lot easier to cut the threads a little more than to uncut them.
Use Permatex or Loctite thread sealant on the male threads of the adapter and a little coolant to lube the o-ring on the sender and you can continue to use your current manifold and sender.

 

The information Bunny gave about BSPT threads is incorrect.

If that sender does, in fact use a straight thread, it will be a common metric thread, Not BSP.

BSPT stands for British Standard Pipe TAPER thread. The S does not stand for straight.

Actually, any Toyota tapered threads are JIS (Japanese industrial standard) pipe thread, but the difference between BSPT and JIS pipe thread is insignificant.

BSPT is NOT a straight thread. It is tapered, similar to NPT. British straight pipe thread are called BSPP (British Standard Pipe Parallel)

I dont't think any of these BSPP threads are ever found on Toyotas.

Look here.:BSPT Threads - British Standard PIPE Taper Thread Dimensions & Specifications (torqbolt.com)

If it is indeed a straight thread that requires the sender to seat on a shoulder, some sort of adaptor may be required, but if it is BSPT, cutting some more thread, and careful seating of the sensor may suffice.