23 replies to this topic

[masslaw]

Because I can't see the temp gauge in the middle of the 3-clock dash very well, I added another electrical gauge with a takeoff from the thermostat housing. When running, the original, middle-clock gauge reads normal, right in the middle.  The Smith gauge reads very high, almost at the "hot" mark.  I'm wondering what temp the Smith's considers normal as I would love to see the needle at the N. I can live with it but if there is a way to somehow modify it I would like to do it.  Are there different sending units?  Is there something I can splice into the wire coming from the engine?  A resistor or something. Thanks.

[Tds76]

I had a similar problem with my new Smiths BT2204/11 temp gauge - the car is running at a normal temp, but the gauge was reading high. I changed the temp sender from GTR104 to GTR101 and it now reads in the middle.

 

From a lot of Googling while trying to understand the issue:

 - There is a lot of variation in quality & accuracy of the temp senders

 - The earlier/original gauges are adjustable through two slots on the rear. I am not sure if this applies to the new ones as well. 

[Johnmar]

As you both are talking about an seperate temp guage (as: not in a combined cluster) I was wondering: could it be related to your "power source" / temp sender combination:

The combined cluster will use a volt stabilizer (according to the text below reducing the operating voltage to 10V). Just try to hook up your external gauge to the stabilized volt output (10v) and see what that does.

 

(for info in difference between the mentioned senders https://www.mmoc.org...69aa27&start=20)

 

Theory of Operation:

Early British cars (prior to the mid-1960s) did not always utilize a voltage stabilizer and their instruments operated at full battery potential. The voltage of the car’s electrical system would change according to the operation of the charging system and what loads were put on it. This changing voltage allowed the instruments to behave erratically or inaccurately.

The Smiths voltage stabilizer is a mechanical voltage regulator that reduces and maintains the instrument operating voltage at 10v dc. Inside the stabilizer is a bimetallic strip, an insulated heating wire coil, and contact points.

 

[Tds76]

Johnmar,

You may be right, I assumed it was already a 10V Smiths gauge. 

 

When I bought my current Mini it had a non-VR temp gauge fitted, only wired in with the VR. My long winded problem solving write-up is at the following:

http://www.ausmini.c...=99842#p1058188

 

After i'd fitted the correct gauge for VR it was reading on the high side, I had the GTR101 sender in the garage so changed it and it fixed the issue.

 

 

Cheers, Paul. 

Edited by Tds76, 08 June 2021 - 05:48 AM.

[masslaw]

The gauge is on a 10 volt source.

[brivinci]

I have the same issue with a VDO gauge I installed. I did aux oil temp, water temp and oil pressure. I got nervous when I looked down and my water temp was near 250F and my oil pressure was down around 20psi. Turns out both gauges are off. My original temp gauge reads spot on. The VDO reads high and fluctuates a lot. It will go from 220-250 and then back down to 220 in less then 30 seconds some times. I fitted a trusted mechanical oil pressure gauge and it proved just how off the electric oil pressure gauge was. I even replaced the sending unit for the pressure and its still reading low.

 

You got me thinking about the stabilized voltage...only, one reads high and the other low....and the oil temp seems to read ok (but that one I have no way to test against). For the Smiths gauges, does it specify that it should be wired up to the stabilized voltage?

[masslaw]

Smiths instructions say 10 volt for fuel, water, and oil temp

[Tornado99]

Johnmar,
You may be right, I assumed it was already a 10V Smiths gauge.

When I bought my current Mini it had a non-VR temp gauge fitted, only wired in with the VR. My long winded problem solving write-up is at the following:
http://www.ausmini.c...=99842#p1058188

After i'd fitted the correct gauge for VR it was reading on the high side, I had the GTR101 sender in the garage so changed it and it fixed the issue.


Cheers, Paul.

Is there a way to determine what type sender is present? I want to try the different part number on my car but do not know what I have now.

[masslaw]

I had another sender in my part box.  THey were identical except that the one on the car had a red tip at the spade connection end and the second one had black.  I switched them and the gauge reads correctly now.  Don't know about the part numbers of these two.

[Tds76]

 

Johnmar,
You may be right, I assumed it was already a 10V Smiths gauge.

When I bought my current Mini it had a non-VR temp gauge fitted, only wired in with the VR. My long winded problem solving write-up is at the following:
http://www.ausmini.c...=99842#p1058188

After i'd fitted the correct gauge for VR it was reading on the high side, I had the GTR101 sender in the garage so changed it and it fixed the issue.


Cheers, Paul.

Is there a way to determine what type sender is present? I want to try the different part number on my car but do not know what I have now.

 

 

GTR101 has a black end & 104 is red.

 

Note that the photos used on Minispares website show both as black - this is not correct.

 

Cheers.

Edited by Tds76, 09 June 2021 - 09:32 PM.

[Tornado99]

 

 

Johnmar,
You may be right, I assumed it was already a 10V Smiths gauge.

When I bought my current Mini it had a non-VR temp gauge fitted, only wired in with the VR. My long winded problem solving write-up is at the following:
http://www.ausmini.c...=99842#p1058188

After i'd fitted the correct gauge for VR it was reading on the high side, I had the GTR101 sender in the garage so changed it and it fixed the issue.


Cheers, Paul.

Is there a way to determine what type sender is present? I want to try the different part number on my car but do not know what I have now.

 

 

GTR101 has a black end & 104 is red.

 

Note that the photos used on Minispares website show both as black - this is not correct.

 

Cheers.

 

Grt...mine is black casing...and yes, the MS photos for both are black, so that threw me. Will try a red as my gauge never gets much over 1/4-1/3 off the cold position. 

[masslaw]

Back again.  I switched to a black tipped sender - supposedly the GTR101 - and thought I had fixed the problem.  But.... when out on a short road run, the temp needle stays just above the N for a while and then creeps up to almost the H.  The in-dash gauge that I trust but can't see very well, reads normal and the extra fan does not engage.  So I am assuming I am not overheating. This is a Smiths electrical gauge and the sender is in the thermostat housing.  I ordered and received a new GRT101 from Mini Sport so I'll try that.  In the meantime, any suggestions?  It has a 10 volt conncetion.

[Johnmar]

Why not install a potentio meter/variable resistor. That way, you can tweak the signal to the external meter.

Worth a try

[Tornado99]

Back again.  I switched to a black tipped sender - supposedly the GTR101 - and thought I had fixed the problem.  But.... when out on a short road run, the temp needle stays just above the N for a while and then creeps up to almost the H.  The in-dash gauge that I trust but can't see very well, reads normal and the extra fan does not engage.  So I am assuming I am not overheating. This is a Smiths electrical gauge and the sender is in the thermostat housing.  I ordered and received a new GRT101 from Mini Sport so I'll try that.  In the meantime, any suggestions?  It has a 10 volt conncetion.

Could your voltage regulator be the issue? Put a voltmeter on the regulator output to see if it is wandering. There are solid state regulators from MiniSpares to replace the original mechanical one. 

[masslaw]

I have a solid state regulator.