13 replies to this topic

[mk3cortina]

where exactly should i be looking to fit the water gauges temperature sender? i know that the alloy radiators you can buy have a threaded hole in them for these, but i dont have an alloy rad so really im asking is there a blanked off threaded plug anywhere on the water system of my 998? or do i need to buy an adaptor tube that i put on a hose somewhere.

[kanye]

should be a hole in the cylinder head under the thermostat..?

[mk3cortina]

excellent, just hope this gauge i have has the right thread to fit.

[kanye]

do you mean the sender..? and there should be a "hole" to fit the sender on the head in under the thermostat, also when i fitted a new sender to mine last week i wrapped the thread in PTFE tape to be sure of no leaks!

[mk3cortina]

yeah the sender, the threaded plug thing. also yeah i was thinking i should use ptfe tape or some of the liquid gasket stuff i have.

[Dan]

The threaded ports in rads are for auxiliary fan switches, not gauge senders.

[mk3cortina]

well, it went in and fits, took a little bit of persuasion to get the long non threaded sensor part into the head but i think it was down to a bit of crud build up on the original bolt/plug in there.

[mgb1978]

Not recommended to use PTF tape or liquid gasket on the Temp sender.
It has to earth through the head to work properly.
It is a taper-fit so it should seal OK , just make sure the tapered bit behind the threads is clean.

[mk3cortina]

i didnt use anything on it anyway, seals fine. just out of intrest, i tried checking it works by putting it in hot water, and the needle moved a little, but does it need to be electrically powered to work? because all there is, is the sender wire, and the bulb holder with one wire coming from it, then the threaded post in the middle of the gauge.

[mgb1978]

See here for an explanation of how the thing works
http://www.secondcha.../public/653.cfm

The wire going to the sender is basically the earth wire for the guage. The sender is a bit like a dimmer switch, the hotter it gets the more current it lets through to earth and this moves the needle on the guage.
To check if the guage itself is working turn on the ignition, take the wire off the sender and touch it to earth. The guage should now read "very hot".

[mk3cortina]

ahh right, well its only connected up via the sender, the dial itself is just push fitted into an alloy dash i have, do i need to run a wire to the threaded post on the back of the dial? or will this just work with the sender wire.

[mgb1978]

They're should be a live wire attached to the back of the gauge. This wire should come through the voltage regulator to stabilise the current and stop the needle fluctuating.
The voltage regulator feeds the fuel gauge as well, so that should help you find it.

[mk3cortina]

oh right, well all ive got on the back of the gauge is:- the thick sender cable, a bulb holder with one wire coming from it at the bottom and this has a bent clip on the side at the top of it, and the threaded post. its a tragonic gauge.

Edited by mk3cortina, 15 September 2010 - 07:26 PM.

[mgb1978]

Sorry, but I don't know anything about Tragonic gauges (except that they are fairly old).
Not trying to be funny but is it definitely an electrical gauge ?
A lot of the very old ones were mechanical and that thick wire you mentioned might be a small-bore tube.