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harrytr5

temperature gauge

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Hi, oh sage ones.

I have tried everything to bring the temperature gauge to read normal.

Substituted the gauge(rebuilt) with another and get the same reading past the H (hot).

Changed the Moss thermostat bellows for a genuine made in England bellows (real quality).

Changed the thermo switch three times and now using a genuine new, old stock.

Clamped the bypass hose and no change.

At all times the Lazer thermo gun is telling me 68-80C

So not boiling over and has not in 80 miles of driving

Rebuilt engine with quality parts and of course not run in.

Original new/old qaulity thermostat bellows

Pacet fan.

Changed voltage stabiliser to electronic one

Is the thermo switch not matched to the gauge?

What is going on?

It is driving me crazy(or not)

Regards Harry

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Hi Harry,

what car is the problem on. 4 or 4A.

 

The 4A does not need a bellows thermostat.

Have you used the correct modern wax stat if a 4A.

 

You say the Laser Thermo gun shows a lower temp 68-80 are you using it correctly. The paint surface (colour and shine) can affect readings.

 

There are different sensor bulbs (see the colour ring around the end).

 

There is a company in Wales that can test the temp gauge properly.

 

Have you tried dunking the sensor bulb in a pan of varying temp water and seeing the gauge response.

 

Roger

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The 4A does use a sleeved bellows thermostat. At least mine does.

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Hi Pete,

I asked the question last week on a similar thread and I was told the 4A has a different size of outlet that doesn't require the bellows stat.

 

Roer

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Thats interesting Roger,I thought the TR4a had to have one. The bypass hose has an oval hole cast into it not a round one I presume to restrict flow.

All other gauges work fine. Yes the Thermo gun works fine although new to me as my other gun decided to pee me off and not work.

The engine ticks over not boiling and staring at me with a smirk and defiantly daring me to solve it!

Regards Harry

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If the voltage stabiliser is OK It sounds as though the temperature sender is not matched to the gauge. There are a variety of senders with different resistances and using the wrong one will result in an incorrect reading. You say the gauge has been refurbished so I suggest you ask whoever did it what sensor it was calibrated with and then try to source that type.

 

The alternative is to recalibrate the gauge yourself to match the sender, which is do-able though maybe only to get the 'normal' reading right. (if the 'span' of resistance change is wrong its difficult to match over the whole range without fiddling with extra resistances in series or parallel, and probably not worth the effort as you only really need to identify changes away from normal.)

Google will give lots of hits for "smiths temperature gauge recalibration", like this:

 

https://www.triumphexp.com/phorum/read.php?9,1405143

Edited by RobH

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Agree with all of above, but I would start by removing the sender from the engine, dunk it in a bowl of water heated to approx 185°F, connect up & compare the reading you get with a known to be good thermometer (i.e. an electronic type used for cooking etc)

Only then will you know if the problem is the gauge or the car.

 

Bob.

Edited by Lebro

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Bob, I suspect you've got your Cs and Fs muddled (reminds me of an old joke...)

 

Pete

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Thats interesting Roger,I thought the TR4a had to have one. The bypass hose has an oval hole cast into it not a round one I presume to restrict flow.

All other gauges work fine. Yes the Thermo gun works fine although new to me as my other gun decided to pee me off and not work.

The engine ticks over not boiling and staring at me with a smirk and defiantly daring me to solve it!

Regards Harry

No need on a 4a as the bypass diameter on the thermostat housing and the water pump body was reduced to negate the need.

Stuart.

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Sounds to me like the gauge may be getting 12v not 10v ( which is what the ‘stabiliser’ averages out tomover time)

 

Or its the sender, or the gauge :-)

 

Its a very simple circuit so you should be able to find the culprit Harry.

 

Steve

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Bob, I suspect you've got your Cs and Fs muddled (reminds me of an old joke...)

 

Pete

Was that the Essex girl joke ?

 

Post corrected - I was wondering who would spot that deliberate mistake :ph34r:

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Was that the Essex girl joke ?

 

 

No, that was C and A.

 

Pete

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:D:D:D Thats the one :ph34r:

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