7 replies to this topic

[proccy13]

Just wired in a Smiths oil temperature gauge last night into my 1984 Mini, 1330cc fast road car.

They are standard Smiths gauges but just have stickers on I’ve added (see pics)

The temp sender are part no. GTR101, in the flow for the oil with a DSN filter head.

For the oil temp gauge I wired in 10V from the voltage stabiliser, earth wire to the bracket and sender wire to the other terminal - as instructed.

Whilst doing this I noticed that my coolant gauge in fact wasn’t using a 10V supply I thought it had from the stabiliser, and in fact had a 12V ignition feed, and didn’t even have an earth (no earth through casing as it’s a plastic surround). I guess the sender may be acting as the earth??

Unbeknownst to me I’d had the coolant gauge wired this way for a few years and the gauge was reading very accurately with readings from an IR temp gun helping to show its accuracy (as pic shows), so I thought the voltage stabiliser was doing its job!

Because I knew it shouldn’t be on 12V, I changed it to 10V from the voltage stabliser whilst doing the oil temp gauge.

However, now my coolant gauge reads just above ’C’ when at proper operating temp (88 degrees) and the oil temp gauge reads only at 60 degrees after 30 mins of driving hard which I know is far too low, and show be around 100 degrees ish.

So, Should I wire them both to 12V ignition even though they should be on 10V as I know the coolant gauge was accurate on 12V?

Can anyone explain? Was always told 12V would damage gauges and give higher than true results..

I hope this all makes sense.

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[tmsmini]

Later and current Smiths gauges use 12 volt unless it is a direct replacement for the voltage regulated gauges.

Caerbont has some support documents here:

 

https://www.caigauge...ct-instructions

 

https://www.caigauge...diagram-366.pdf

 

Identifying the specific gauge will help.

[Spider]

Some of the very latest Smiths Gauges are stepper motor types and use a direct 12 Volt supply. These are infact made by VDO.

 

Many of the early 60's to present day Smith Gauges are a thermal type of Gauge (the action of them, not what they are measuring) and are 10 V. There were some though on that date range and prior that were a direct 12 V Gauge.

 

So, while not exactly helpful here, what you have there could be a 10 V or 12 V Gauge.

[sonscar]

I understood that the 10v regulator was to provide a stable voltage to ensure consistent readings as battery voltage varied from 11ish to 15ish and would cause inaccuracies.,Steve..

[proccy13]

Later and current Smiths gauges use 12 volt unless it is a direct replacement for the voltage regulated gauges.

Caerbont has some support documents here:

 

https://www.caigauge...ct-instructions

 

https://www.caigauge...diagram-366.pdf

 

Identifying the specific gauge will help.

 

 

Some of the very latest Smiths Gauges are stepper motor types and use a direct 12 Volt supply. These are infact made by VDO.

 

Many of the early 60's to present day Smith Gauges are a thermal type of Gauge (the action of them, not what they are measuring) and are 10 V. There were some though on that date range and prior that were a direct 12 V Gauge.

 

So, while not exactly helpful here, what you have there could be a 10 V or 12 V Gauge.

 

Thanks for that Spider and tmsmini,

 

The coolant temp gauge in the first picture is a 'BT 2204/11' and ran very accurately from 12V as described in the original post (88 degrees 'normal' - marked with blue triangle on gauge, 105 degrees 'getting hot' - next red triangle and 110 degrees 'hot'- last red triangle), before I changed it to 10V stabilised when wiring in the new oil temp gauge.

 

The oil temp gauge (which used to have a coolant sign where the new 'oil' tag has been stuck over it) is an 'ACT 2202/01'.

 

1.Does that help identity them to being 12V kinds? 

 

2.Finally, do they both use then sender as an earth to answer my question in the original post? The coolant temp gauge has run without one for years unbeknownst to me.

[minifreek1]

You learn something new everyday, always thought they all ran on 12V....

[tmsmini]

I would reach out to Caerbont with the part numbers to sort out which category your gauges fit into.

They have a form here:

https://www.caigauge.com/contact-us

 

And other contact info:

Caerbont Automotive Instruments Ltd.

Abercrave

Swansea

SA9 1SH

T: 01639 732200

 

I had forgotten the early cars were also twelve volt and we have a 64 Traveller that originally had an unstabilized gauge.

[Mr Piggy]

In my experience with other makes the gauges that need a voltage stabiliser react slowly whereas the directly wired 12v ones ping up immediately. The 12v ones need an earth, usually through the metal body of the gauge to the dashboard as well as the feed and sender connections.