Zetec Oil Pressure Sensor thread size?

[.Adam.]

Does anyone know what the thread size is for the oil pressure sensor on a Zetec Blacktop (Phase 3)? I've got a new sensor to fit, which is an m10 thread, but it's too small, so I need to get an adaptor. The M10 is roughly 50% too small, with too fine a thread as well.
If not, does anyone know where I might be able to find out?

[andy-xr]

1/4 NPT on the silver top, pretty sure the black top is the same

I got a couple of 1/8 - 1/4 step up adapters from Tubes, Fittings and Valves, contact details here if you want to give them a try: http://www.applegate.co.uk/company/11/89/566.htm

No connection with them other than a customer

Edited by andy-xr on Wednesday 19th November 20:08

[.Adam.]

Forgive me for being stupid, but a 1/4npt is 1/4 of an inch in size with a tapered thread? Which makes it smaller than an M10 bolt? I've either misheard what my garage said about the hole in the block being too big, when it is actually the sensor thread that is too big, or my block hasn't got a standard size hole! I shall have to ring up my garage tomorrow that to see if I have got it the wrong way round.

[Martin Keene]

Nope, 1/4" NPT is a pipe thread and the 1/4" relates to Nominal Pipe Sizes, which is loosely related to the inside diameter of schedule 40 pipe. Because of the pipe wall thickness, the actual diameter of the threads is larger than the NPS, considerably so for small NPS.

[.Adam.]

Martin Keene said:

Nope, 1/4" NPT is a pipe thread and the 1/4" relates to Nominal Pipe Sizes, which is loosely related to the inside diameter of schedule 40 pipe. Because of the pipe wall thickness, the actual diameter of the threads is larger than the NPS, considerably so for small NPS.

So does that mean that 1/4"npt is bigger than M10?

[.Adam.]

Just answered my own question, looks like 1/4npt is bigger than M10, think I need one of these adaptors:

[Pumaracing]

Reminds me somewhat of a numpty customer of mine many years ago trying to build his own CVH engine. Being an obsessive compulsive type he decided that after having had it reconditioned he wanted to make the head perfect before reassembling it by running a tap through every thread in the thing. Nothing wrong with that of course, I do it myself on every job - provided you actually get it right. Most of them were easy for him, 8mm standard coarse threads on the manifold studs and 6mm coarse on most of the rest which he had taps for in his tool kit. The one that stumped him was the temperature sender thread although why he didn't leave the damn thing alone god only knows.

So he phones up a Ford dealer to ask what the thread size and pitch is. First mistake because the minions there are only going to read something off a CDrom without understanding it. So they tell him it's 10mm x 1mm. Maybe they said 'about' 10mm x 1mm but who knows. Well of course it isn't a metric thread, it's an NPT being a taper sealing pipe thread. Specifically a 1/8" NPT which at 10.29 x 27 tpi is nearly 10 x 1 if you round the numbers to the nearest whole unit which is what the Ford dealer did.

So he goes out and buys a metric fine parallel 10mm x 1mm tap, runs it right through the NPT taper thread in the head, without apparently realising that perhaps he shouldn't be graunching quite so much aluminium swarf out of it, and then finds the temperature sender doesn't fit at all anymore and he's scrapped the head after having all the other work done to it. Eh bah gum, you've got to laff.