Thread size of dash temp sensor

[Sam_Q]

I wish to know what the story is with the thread size is used on the sensors for the dash temperature gauge for A series engines and probably many others.

It's supposed to be 3/8NPT but why is it that if you try and tap the thread you only need to wind the tap in about a third of the way for the toyota sensor to wind right in? however on the OEM gear they have the threads tappered right into the hole. Do they use some special undersized tap or something?

[CrUZida]

According to the Tridon page its a 1/8 Gas thread.

[Sam_Q]

gas thread? as in BSPT?

[CrUZida]

As in google.

[Sam_Q]

well yeah that's what I did to find out people where using bspt and gas thread for seemingly the same thing. Doesn't make sense though as a 1/8" size would only require about a 9mm hole pre drilling hole.

[CrUZida]

Given that 3/8" is 9.5mm, you'd only require a 9mm pre drilling hole for that aswell.

I'm not sure I follow?

The other model of sensor uses a 16x1.5 thread (1UZFE for example)
Its not this is it?

[AAAAGZE]

Given that 3/8" is 9.5mm, you'd only require a 9mm pre drilling hole for that aswell.

I'm not sure I follow?

The other model of sensor uses a 16x1.5 thread (1UZFE for example)
Its not this is it?

gas threads come in parallel and tapered versions, and when they refer to the 3/8 it is the flow diameter, not the thread diameter as is commonly assumed.

be careful when mucking around with these threads.

bsp is more commonly used on jap and english cars, where npt is more likely to be found on yank cars and their derivatives.

some threads are compatible in the same diameter, but more often than not they are a thread or two out.

a lot of fluid/gas transfer fittings will use these threads.

[CrUZida]

In that case then I think the OP has the 3/8 NPT mixed up with the 16x1.5 thread used on other Toyotas.
They use a copper washer to seal instead of taperring.

[AAAAGZE]

3/8 npt and bsp would be a very similiar size to 16x1.5

pitch is a bit off, and also marginally larger.

[Sam_Q]

well it's a tapered sensor and sure as hell not metric, I tapped a 16x1.5mm a while ago and I really wish they used those. The reason I said needing a 9mm pilot hole didn't make sense is because of the physical size of the sensor. It measures up and has the right thread count for the BSPT 3/8 but they just don't fit as well as they should.

[Sam_Q]

Here's what the Tridon catalouge says:

TTS006 Water Temperature Sender (Gauge) 08/1983 08/1983 Temperature sender TTS006 (M16 x 1.5 thread, 1 terminal blade type).

now here is the really confusing part, I checked and sure enough it is very close to 5/8" 19TPI but if I am wrong and it's not a tappered thread then how does it seal off when it has no copper washer? does it use the end of the sensor that's not threaded to jam in? the other thing is I ran a 16 x 1.5 tap I had down a spare reart housing off a 16V and it started really nice and then a few threads in it started to cut metal, it's like it's a tappered thread still??

[30psi 4agte]

hmmm i thought it was a metric thread. if it is the sensor im thinking of it should have a washer behind it... mine does.

Im wondering if someone has stuffed the wrong sensor in your at some time????

[Sam_Q]

well I have seen like literally 50 of these now and never one with a washer. Time to pull one out of my own car tomorrow just incase the 4age one is different which I highly doubt.

[30psi 4agte]

you are talking about the sensor at the front of motor that the top radiatior hose goes onto? or have i got it wrong?

mabe i have a different sensor in my housing.?.?.?

[Sam_Q]

yes that's the one, assuming they are the same as the 4ac engine which I am pretty much completely confident they are

your engine is looking as awesome as ever too