Adapter required, 1/4NPT female to M18x1.5 male

[aww999]

Trying to fit an oil temp gauge into my supra. The (frankly bizarre) temp sender arrangement consists of a captive nut thingy, which butts up against the sender (approx 9mm diameter and 40mm long), and is designed to screw into one of three adapters. None of the three adapters fit any of the holes in my car, and the thread on the captive nut seems to defy categorisation. (Parallel thread, 15.5mm across flats, neither 1.5 or 1.25mm thread pitch. Not 5/8BSP either, totally wrong thread pitch.)

So I think I'm going to end up using the supplied weird-captive-nut-to-1/4NPT adaptor, and go into a 1/4NPT to M18x1.5 bush (or female to male adapter if you like), and use said bush as the new sump plug.

However, I can't find anyone who supplies a 1/4NPT to M18x1.5 fitting. Everything is geared up for 1/8NPT and the temp sender is too big to poke through the hole in the middle of a 1/8NPT fitting. Anyone got any ideas where I could try, or a different way of doing it that doesn't involve stacking a load of adapoters together in such a critical location?

[dnb]

The captive nut thingy thread sounds the same as one of the smaller spark plug threads.

Le Mans motorsport made me a custom adaptor last time I needed something like this. It might be worth calling them - it was only a few quid.

Come to think of it, any decent machine shop equipped garage ought to be able to do something.

[stevieturbo]

Buy a blank M18 fitting, and drill a hole in it, and tap it to 1/4 NPT with a tap.

Or do the Subaru oil galleries use M18 ? There are adaptors for them isnt there ??


I cant visualise what it is you need to do though....a pic would help. Im sure it cant be that hard really... ( famous last words )

Edited by stevieturbo on Tuesday 26th February 22:14

[dnb]

Subaru do use M18, but the OP wants it in a Supra - no idea what these use.

[GreenV8S]

Think Automotive stocks a wide range of adapters, or if you can work out what the thread is you can simply tap the right thread into a bung. If you know whether it's parallel, the major diameter and thread pitch you should be able to narrow it down.

[David H]

Pirtek are also good, branches in most big towns:
http://www.pirtek.co.uk/