Temperature sender 280i

[mrzigazaga]

Hi peeps..Just wondered if those of you who own a 280i have Stuart Warner gauges fitted and if so could you have a look at what colour the temperature sender is please..Ive tried locating a sender but to no avail as you have to match the sender to what gauge you have..(Didnt know that at the time)..Otherwise i will have to fit a new gauge or maybe a resistor?..But not too sure about that..The one in the picture is white but this was the wrong one..The sender is up near the AAD fixing plate next to the brown plug..(Thermotime switch)..Cheers..Ziga

Edited by mrzigazaga on Thursday 3rd November 12:14

[RCK974X]

I've got a series 1 2.8, and I can't tell what colour the sender is... it's been wire brushed at some time. I did measure it though, and I reckon it's the same as the Smiths 'standard' sender.

[NB. in the olden days when I was young, the Smiths senders were all the same resistance range, and were fed by 10 volts, and the Ford (UK) ones were different and fed by 5 volts. ]

when building a kit with the cologne engines I discovered that a TRIUMPH 2000 MK 1 sender fits in the ford hole, and gives you right readings for a Smiths guage. (I'm pretty sure that's right)

Hope that helps. I think they measure 60 ohms when at normal temp, and the Ford ones were 15 ?

[mrzigazaga]

Thanks mate..Thats worth a try..By the way welcome to wedgeworld..Cheers..Ziga

[RCK974X]

No worries. I did find my old notes, in case it helps with calibration....

Smiths temp senders are -

cold (no needle movement) 1-2 K ohms
'N' (about half scale) 60 ohms
hot (almost full scale) 23 ohms (on Smiths Gauge)


Ford temp senders are -

cold 620 ohms
N 26 ohms
H 13 ohms (on Ford gauge)

MY SW sender measures 65 ohms hot and 1k cold, so looks just like a Smiths one...

[mrzigazaga]

Thanks..I have ordered one but will see what happens when fitted..I have stuart warner gauges and not smiths but will fit and test anyway..If it works it will be a bonus..If it dont then im back to square one..Cheers..Ziga

[mrzigazaga]

Hi Peeps..Well i fittied the triumph MK1 temperature sender and it still reads slightly high..Around 210 instead of 280 like the others..I know that this is not a true reading as ive had a probe thermometer in there and it reads 185 max then the fan comes on..Maybe i do need a resistor..But what type and rating would i need..also would it be in between the sender wire?..Cheers..Ziga

[Wedg1e]

mrzigazaga said:

Hi Peeps..Well i fittied the triumph MK1 temperature sender and it still reads slightly high..Around 210 instead of 280 like the others..I know that this is not a true reading as ive had a probe thermometer in there and it reads 185 max then the fan comes on..Maybe i do need a resistor..But what type and rating would i need..also would it be in between the sender wire?..Cheers..Ziga

There are clever formulae that would tell you the value of the resistor you need but in order to use them you'd need things like the resistance of the meter, current drawn by it etc. etc..
I'd do it empirically: get hold of a selection of resistors from Maplins (pennies each). Snip the wire from the sender and twist the ends around the resistor leads. Once you've established the best value, solder and heatshrink it.
As a starting point I'd try 47 Ohm, 100 Ohm, 220 Ohm, 470 Ohm and 1000 Ohm. You can add them in series so for example 220 + 100 Ohm = 320 Ohm. So you could have 47-100-147-220-267-320-367-470-517-570-617-690-737-790-837-1000-1047 etc.
If 47 Ohm by itself knocks the meter flat then you may have to go down by a factor of 10 - 4.7 Ohm, 10 Ohm, 22 Ohm etc.
If you have 1837 Ohms (all six resistors daisy-chained together) and the needle's hardly moved then go up by a factor of ten: 470 Ohm, 1000 Ohm, 2200 Ohm etc.
Get 0.5 Watt or even 1 Watt rated resistors to make sure they don't cook due to the dissipated heat. If it turns out you need a vey low value (say 0.47 or 1 Ohm) you'll need to use a higher-wattage resistor - as an example 12v dropped across 1 Ohm would be producing 12 Watts of heat - not likely here though you may find you need a 2W or 5W resistor at the final calibration value.

[mrzigazaga]

Thanks Ian..Ziga

[RCK974X]

Again, in case it's any use to anyone .....

Talking formulas, the Smiths and Ford standard types are 'hot wire' cheap and nasty guages, and so they correspond roughly to I*I*R through the guage (or in plain words the current heats the wire to move the needle).

But the SW guages respond instantly, so I reckon they are not hot wire types.

Ziga - My wedge always read high about 3/4 of the guage when engine warmed up, even though I have an SW sender (it looks like your pic at least) I changed the thermostat etc, but reckon it wasn't actually hot. It didn't lose water for example. A 15 ohm resistor in series with the sender makes it read just about 1/2 scale.....

As wedg1e says, if you go that way make sure you get a square ceramic high wattage version, as there is significant current going through it, enough to blow a little tiny one. Mine is 2 watt I think.

Edited by RCK974X on Saturday 19th November 21:30

Edited by RCK974X on Saturday 19th November 21:32