Smiths water temp sender

[JC T ONE]

Hi all,

My water temp gauge dont show the correct temp

I have tried several different senders (std Mini items) but the needle only moves a little bit, when it gets hot.

If I unplug the wire on the sender, and stick it direct on to the engine block,
the needle then moves nice and evenly all the way up to 110 degrees,
so I guess I have the wrong sender ?

The gauge is a 2" (52mm) Smiths (half scale & original 1973 model) the scale reads " 30 75 85 110 "
I have been told me there is a different sender, for some of the Smiths temp gauges.


Jens Christian

[abri]

Thanks for posting this Jens. I have a similar problem. There are definitely different senders that have to be matched to the correct gauges. My problem is I ordered a 'correct' sender for a 66 temp gauge from Somerford...but my gauge only reads about 1/4 warm (halfway to N). I'm baffled because the Mk1 gauges used the same sender from when they were introduced with the oval 3 clock binnacle until after my car was built....didn't they?

[JC T ONE]

There are definitely different senders that have to be matched to the correct gauges.

I'm baffled because the Mk1 gauges used the same sender from when they were introduced with the oval 3 clock binnacle until after my car was built....didn't they?

Hope someone inhere knows more ? I dont



Here is another question =

Does ALL Smiths electric temp gauges have to be connected to the volt stabilisor ?

This looks like a Smiths accessorie gauge, and I heard that some (these) dont need the volt stabilisor?


Edit - Had a look and the Smiths gauge no is TC4308/00 so does anyone have a Smiths parts book ?

[Tim]

The way I understand it, the factory fitted temperature gauges did use the 10v regulator, whereas aftermarket ones sold in car accessory shops just ran at the unregulated nominal 12V. I have no idea whether the gauges were different, or the senders.

Tim

[abri]

Somerford lists these options

GTR102 TRANSMITTER, water temperature 1 1961-64.
GTR104 TRANSMITTER, water temperature 1 1964-69.
GTR101 TRANSMITTER, water temperature 1 1969-85.

and they list four different gauges up to '67.

TC4303/06 GAUGE, water temperature, black face 1 1961-62, Cooper (5L271).
TC4303/07 GAUGE, water temperature, black face 1 1961-64 Super, 1962-64 Cooper, 1963-64 Cooper S (13H827).
BT2204/04 GAUGE, water temperature, black face 1 1964-67 (13H2137).
BT2240/00C GAUGE, water temperature, black face 1 1964-67, alternative.

I guess its a question of not only checking you've got the right sender for your year, but also checking you've got the right gauge. I had no idea there were so many different versions of the Mk1 gauge.

Jens, gauge no TC4308/00 does not appear in the list for later minis so my guess it's from another car altogether.

[JC T ONE]

The way I understand it, the factory fitted temperature gauges did use the 10v regulator, whereas aftermarket ones sold in car accessory shops just ran at the unregulated nominal 12V. I have no idea whether the gauges were different, or the senders.

Tim

Hi Tim,

yes that is also my understanding, here is a link with a pic of it = http://www.rootesparts.com/id181.htm

I was in the garage yesterday, and had a look, at one that was removed from a lowmilage / one owner / unrestored 850,
who had quit a few options fitted by the local BL dealer, it was the same as mine, and it was not connected to the volt stabilisor.
So that might be my problem ? unfortunally do I need to remove the dash to move the wire.

[JC T ONE]

Jens, gauge no TC4308/00 does not appear in the list for later minis
so my guess it's from another car altogether.

Hi Abri,

I found it in one of my old 60/early 70ies catalouge, it is a aftermarket item.

As I stated above am I sure it dont need a volt stabilisor (maybe one is built into it?)

[mini129]

Smiths Gauges for a mini fitted into 2 categories
Pre September 1964 & post.
The earlier ones were called semi conductor or ratio gauges, the parameters 83-3 ohm and the pointer flops around a lot to use a technical description They were connected directly to 12 volts like the fuel gauge in early cars. The top of the sender was green.

The later ones were bi-metal the parameters 250-19 ohms and the pointer moved slowly. these are connected through a voltage regulator with a regulated 10 volt output as was the fuel gauge.

Cross coil smiths gauges working on 12 volts with dampened pointer movement didn't appear until the mid 70's and were not in a mini as far as I am aware. They were also not part of the current Caerbont Smiths range until recently.

Prior to the mini there were smiths gauges with a regulator contained in the sender in Bentley, Mg magnettes etc but that is another story.

[JC T ONE]

Cross coil smiths gauges working on 12 volts with dampened pointer movement didn't appear until the mid 70's and were not in a mini as far as I am aware. They were also not part of the current Caerbont Smiths range until recently.

Hi & thanks for your reply mini129.

I have a spring 1972 dated JanSpeed catalouge, and it has the TC4308/00 gauge in it.

My gauge was fitted by Wood & Pickett (autumm 1973)
The other one I have, was fitted by a BL dealer, when the 850 Mini was new (also a 73 car) so I asume it has been in the BL 70ies accessorie catalouge too

I was in the garage tonight, and checked the spare gauge I had.

connected it to 12 volt, and put the sender in the kettle, and it came up to 85/90 degrees.

I then pulled back the dash, to check if my gauge was connected to the stabilisor ?

It wasnt, it had 12volt directly to the gauge, so maybe there are TOO much resistence in the wire, going from the sender to the gauge ?
will investigate tomorrow, too tired now.

[mini129]

I think you will find from the photo I found of your gauge that it is the cross coil one. It still uses the 250-19 ohm sender which is readily available. The resistance of the wire is unlikely to be the problem, resistance to earth can be a problem but in this case it would make the gauge read high not low.
As for grounding the wire and the gauge going to 110c if you think about it you are introducing 0 ohms to the gauge where 19 ohms is full so of course it will go full scale.

[JC T ONE]

Hi & thanks mini129.

first thing will be to fit an extra wire, from a headstud direct to the body on the sender, to rule out bad earthing.

Next step will be a external wire from sender direct to gauge, to check if the loom is causing the problem?.

last step will be to remove the gauge, and do a test on the work bench.

[JC T ONE]

Did all of the above steps, and found a poor connection on the T terminal.

I will now get a specialist to check the gauge.

[Spider]

Hey guys, just saw this.

Does your fuel gauge work OK?

Reason I ask is because it could be the regulator / stabalizer. They do have a 10 volt output but it is hard to measure with a meter as they are an old fashoined vibrating reed type regulator. If you've got a smiths type voltmeter, that is the best way to check it.

There were also 3 types of senders that I know of, maybe more!

I'm fairly sure the temp sender you want is a GTR104 (suited to a 82 degree T'stat), there is a later one a GTR143 (also p/n GTR101), this one gives a mid-gauge reading with an 88 degree thermostat.

[JC T ONE]

Hi spider,

thanks for the listing, of the different sender type.
my gauge is the 12volt type.

[minicentie]

I am having some issues too with the gauge/sender.
At the other forum i also got to the point that there are some 3 different senders used .
I have a 1968 s with original dash so the gauge should be the right one.
The sender is the red top ,conneted to the voltage thing.
When cold the ohm on the sender is around 1500 ohm,i think way to high,almost dubble what is should be.
When the engine is on temp the resistance is 5,4 ohm very low,and the gauge is going of scale?
I haven't got another red top so can't have another reading.
Can some of us measure cold and hot resitance? Should be around 800 cold and 20 ohm hot?
Just to get the right Ohm with the different senders . That way everyone can measure easy if the sender is broken or the problem is further up.
The gauge plays another role but that is pretty much to find in the numbers on it,which are posted here for the mk1 allready. Now about the mk2 and mk3 to?The ones with the rectifier voltage thing in it.