Water temperature sender size

[dern]

How do I go about measuring the size of a thread?

I have a temp sender (electric) screwed into a fiesta (I think) thermostat housing which is bolted to a 1700 xflow engine in my westfield and I'd like to buy a new sender and guage as mine reads too low (the rest of the system works ok).

Is there an easy way to measure a thread or do I take it to a bolt shop and compare it with what they have?

Thanks,

Mark

[nighthawk]

have you got any pictures of the sender?

It may well be a ford part if it's part of the original T stat housing.

Although from memory, the temp sender we used was fitted directly into the OHV head, with a much larger fan switch in the alloy housing.

[GreenV8S]

You can match the thread by measuring the outside diameter with a vernier gauge and then measuring the pitch by taking a whole number of turns (the more the better) and measuring the length, dividing by the number of turns, that gives you the pitch. There are plenty of on-line references that give you the diameter and pitch of all the standard sizes so you should have no difficulty matching it up.

[dern]

nighthawk said:

have you got any pictures of the sender?

Just taken one. It looks like this...



...looks like it fits in the block rather than the thermostat housing so should be a fairly standard xflow fitting I would have thought.

Regards,

Mark

[grahambell]

These senders use a taper thread to seal into the head. From memory it's probably 1/4" BSP taper, which would be about 1/2" diameter.

Obviously you need matching gauge and sender to make sure you get proper reading. Might just be the sender you need to change if you can get one to match existing gauge.

[nighthawk]

That is indeed the standard Xflow position for the temp sender.

Although it's NOT a ford item fitted, can you see if it had a coloured band near the terminal?

Ford senders were identified by this coloured ring.

[dern]

The car has VDO gauges all round so I'll probably try a new VDO sender to match the gauge once I determine the size and if that doesn't work I can pop a new gauge in.

I've checked to see if the sensor wire earths anywhere and it doesn't. The gauge sits at about 50 deg (right on the bottom line of the gauge but not resting against the stop) while the engine is running peaking to about 60 (from memory) as it warms up until the thermostat opens up. The fan runs fine too when the engine has warmed up. The temp moves up and down a tiny bit at standstill as the fan cuts in and out.

Regards,

Mark

>> Edited by dern on Friday 7th May 22:08

[Justin S]

Try cleaning the connection.With a poor one,you might get a higher resistance across it causing the gauge to read low.You could earth the sender lead onto the block and see if the gauge reads max temp.This will also tell you of the gauge operation.Morning Mark.

[dern]

Justin S said:

Try cleaning the connection.With a poor one,you might get a higher resistance across it causing the gauge to read low.You could earth the sender lead onto the block and see if the gauge reads max temp.This will also tell you of the gauge operation.Morning Mark.

Morning .

That's a good idea about cleaning the connection and trying shorting it to the block... must be the lack of sleep addling my brain.

Mark