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Temperature Sender Help !


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#1 psoutzis

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Posted 27 June 2020 - 08:33 AM

Hi all.

 

I have recently changed my clocks from center speedo to 3-clock cooper (see picture) and my temperature gauge doesn't seem to work properly. I had tested the grounded wire on the engine block and the temp goes all the way to hot, which tells me that the gauge and wire are all good. The Fuel gauge seems to have good readings. 

I know that there are different types of sender units that need to match the gauge. That must be the problem, as i have replaced the sender unit with a GTR101 and still the temp reads just a little above hot. 

 

Any help would be appreciated

 

Best, 

Panagiotis 

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#2 Moke Spider

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Posted 27 June 2020 - 09:07 AM

All the senders I've tried in recent years all do exactly as you have found.



#3 sonscar

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Posted 27 June 2020 - 12:56 PM

Its an indicator,is C 50?60?70? Is H 90?100?110?,no one knows and I would say it is not important.Wherever the needle is when the motor is hot is your normal.If it deviates from this whilst driving then investigate.Try not to get hung up over its accuracy( or not).Enjoy driving.Steve..

#4 Compdoc

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Posted 27 June 2020 - 01:50 PM

If normal temperature is showing as just above hot, it wouldn't give you much warning if it did overheat. It might be worth checking that you have just 10v coming out of the voltage stabilizer.

Or failing that, the gauges come apart very easily and you could bend the bi-metal strip that operates the needle, a tad to bring it to show normal.

Of course the gauge could be faulty and they are pretty crude, so taking it apart may show a problem.



#5 Moke Spider

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Posted 27 June 2020 - 06:21 PM

Its an indicator,is C 50?60?70? Is H 90?100?110?,no one knows and ..

 

The 'N' Part of the gauge should correspond to the Thermostat Opening Temperature. There was 2 Thermostats fitted over the years, an 82 and a 88 and there was two senders to correspond to these temps, however, the ones we are now being supplied seem more suited to a 74-750 Thermostat. I've found the current GTR101 and GTR104 to be the same.

 

The GTR104 is (supposed) to suit an 820 Thermostat and the GTR101 an 880 'stat.
 



#6 cal844

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Posted 27 June 2020 - 09:54 PM

I have the same issue on my clubman Estate, it sits just under the red portion of the guage with the thermostat open, I've tested the guage buy earthing the signal wire, guage goes to hot...

I have also tried different thermostats but the guage still sits at the same point and doesn't move, the engine runs at the same temperature (verified with an IR gun)

So apart from checking the voltage out of the stabilizer or fitting a small transformer to bring the needle to the middle I just live with it. The car gets checked for fluids before every journey anyway (habit from me, but some fluid is cheaper than rebuilds or insurance claims)

Hope this helps

Cal

#7 Compdoc

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Posted 29 June 2020 - 09:33 AM

Not a cheap option I know, but a gauge matcher will allow you to interpret any signal from the sensor and display any reading on the gauge, in 5 different areas and drive a high or low warning light.

I'm using one on a fuel gauge but it can be used on most types of electrical gauge.

https://www.carbuild...i-gauge-matcher

 



#8 Tornado99

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Posted 30 June 2020 - 02:01 AM

Hi all.

 

I have recently changed my clocks from center speedo to 3-clock cooper (see picture) and my temperature gauge doesn't seem to work properly. I had tested the grounded wire on the engine block and the temp goes all the way to hot, which tells me that the gauge and wire are all good. The Fuel gauge seems to have good readings. 

I know that there are different types of sender units that need to match the gauge. That must be the problem, as i have replaced the sender unit with a GTR101 and still the temp reads just a little above hot. 

 

Any help would be appreciated

 

Best, 

Panagiotis 

 

There was another recent thread on this issue, gauge not reading much above the C mark at fully hot engine. The conclusion turned out to be the car was not tuned correctly, and was actually running at a lower than normal temp. It needed more advancement on the ign (the owner stated 4 Deg. more). 

 

Basically, you need to confirm the actual temp of the coolant to see if it is correctly being reported on the gauge. Another possible explanation for too low a real engine temp is the thermostat stuck in the open position. Also, th temp sender might have been installed with a sealant tape or paste which is giving some electrical resistance.



#9 viz139

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Posted 01 July 2020 - 09:15 AM

As the gauges are non-limier the first half of the gauge will read 82-88 deg were as the second half only reads 12-18 deg.  A 88deg stat with a 82deg sender will put the needle  half way between  N and H . Always worth checking actual temperature by an independent method.



#10 1984mini25

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Posted Yesterday, 07:25 PM

This is with a Gtr101 sender, an 82 degree thermostat and a radiator header tank temp of 98 degrees (tested with inferred gun).

 

Attached File  IMG_20200712_191251.jpg   20.28K   3 downloads

 

This is my issue of were the temperate gauge sits after 10 miles driving or 30 minis of idling in the garage. If I have to stop in traffic it goes a needles width higher and takes ages to return to ‘normal’.

 

It’s only a 84 standard 998, with cast manifold and pea shooter exhaust.

 

The fuel gauge is about as accurate as you can probably get for a mini and I’ve replaced the voltage regulator with a 10v electronic one a number of years ago. I'm getting a constant 9.8 volts as tested at the temp sender and fuel tank sender wires.

 

So far I’ve tried/ replaced either because they were old or to fix the issue. New gtr101 temp sender (old one just wasn't working/ would take ages to read above cold) new 88 thermostat, all new hoses, new heater matrix, new 3 core standard rad with fan switch, additional wiring and electric fan in inner wing, new radiator cap, new water pump, new 82 thermostat (tested and currently fitted and has made no difference) and the cooling system chemically flushed though 3 times. It’s also been treated to a new set of ht leads and spark plugs (all a lovely light tan colour after driving) and an oil change even though the old oil had only done 600 miles since being last changed.

 

I’ve also noticed the axillary electric fan doesn’t switch on its own (unsure if the sender in the rad is faulty) but turning it on manually it has no effect on the temperature gauge even though the radiator temp drops by 10 degrees.

 

And the only advice I got when I bought the replacement water pump (witch I think was overpriced) from the local independent motor factors was laughed at and “All old cars run hot/overheat”.


Edited by 1984mini25, Yesterday, 07:28 PM.


#11 Chris1275gt

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Posted Yesterday, 09:09 PM

This is with a Gtr101 sender, an 82 degree thermostat and a radiator header tank temp of 98 degrees (tested with inferred gun).

attachicon.gif IMG_20200712_191251.jpg

This is my issue of were the temperate gauge sits after 10 miles driving or 30 minis of idling in the garage. If I have to stop in traffic it goes a needles width higher and takes ages to return to ‘normal’.

It’s only a 84 standard 998, with cast manifold and pea shooter exhaust.

The fuel gauge is about as accurate as you can probably get for a mini and I’ve replaced the voltage regulator with a 10v electronic one a number of years ago. I'm getting a constant 9.8 volts as tested at the temp sender and fuel tank sender wires.

So far I’ve tried/ replaced either because they were old or to fix the issue. New gtr101 temp sender (old one just wasn't working/ would take ages to read above cold) new 88 thermostat, all new hoses, new heater matrix, new 3 core standard rad with fan switch, additional wiring and electric fan in inner wing, new radiator cap, new water pump, new 82 thermostat (tested and currently fitted and has made no difference) and the cooling system chemically flushed though 3 times. It’s also been treated to a new set of ht leads and spark plugs (all a lovely light tan colour after driving) and an oil change even though the old oil had only done 600 miles since being last changed.

I’ve also noticed the axillary electric fan doesn’t switch on its own (unsure if the sender in the rad is faulty) but turning it on manually it has no effect on the temperature gauge even though the radiator temp drops by 10 degrees.

And the only advice I got when I bought the replacement water pump (witch I think was overpriced) from the local independent motor factors was laughed at and “All old cars run hot/overheat”.

Hi
I hope I'm not telling you something you already know and I'm not an electrical expert. The voltage stabilizer is there for the gauges and should be a stable 10v. The temperature sender/transmitter doesn't transmit or send a signal anywhere it is a simple thermistor which on temperature rise the resistance decreases at a known rate, thus allowing more current through, which causes the gauge wire to heat up the bimetallic element that is attached to the needle which then moves the needle.
Now I don't know if this would be a way of solving your problem but it makes sense to me but would need verifying by a auto electrician that it's feasible. If we assume that the new thermistor is operating correctly I would pull the wire off the thermistor and check the resistance of the thermistor cold and then when the engine is up to normal temperature. Now you'll know the resistance that deflects the needle to where it gets to and you'll know the starting resistance so could you not put a small resistor in the wire that goes to the thermistor which should then change the resistance and how far the needle deflects. It might take a few goes but you should be able to get the needle in the right normal place. I'll await my theory getting shot down in flames by the wiring experts on the forum, ha ha!

Edited by Chris1275gt, Yesterday, 11:25 PM.


#12 cal844

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Posted Yesterday, 09:20 PM

This is with a Gtr101 sender, an 82 degree thermostat and a radiator header tank temp of 98 degrees (tested with inferred gun).

IMG_20200712_191251.jpg

This is my issue of were the temperate gauge sits after 10 miles driving or 30 minis of idling in the garage. If I have to stop in traffic it goes a needles width higher and takes ages to return to ‘normal’.

It’s only a 84 standard 998, with cast manifold and pea shooter exhaust.

The fuel gauge is about as accurate as you can probably get for a mini and I’ve replaced the voltage regulator with a 10v electronic one a number of years ago. I'm getting a constant 9.8 volts as tested at the temp sender and fuel tank sender wires.

So far I’ve tried/ replaced either because they were old or to fix the issue. New gtr101 temp sender (old one just wasn't working/ would take ages to read above cold) new 88 thermostat, all new hoses, new heater matrix, new 3 core standard rad with fan switch, additional wiring and electric fan in inner wing, new radiator cap, new water pump, new 82 thermostat (tested and currently fitted and has made no difference) and the cooling system chemically flushed though 3 times. It’s also been treated to a new set of ht leads and spark plugs (all a lovely light tan colour after driving) and an oil change even though the old oil had only done 600 miles since being last changed.

I’ve also noticed the axillary electric fan doesn’t switch on its own (unsure if the sender in the rad is faulty) but turning it on manually it has no effect on the temperature gauge even though the radiator temp drops by 10 degrees.

And the only advice I got when I bought the replacement water pump (witch I think was overpriced) from the local independent motor factors was laughed at and “All old cars run hot/overheat”.

This image is also where my Clubman estate's guage sits at operating temperature (thermostat is a 82° stat, IR gun measures 84° after a good 30 minute drive, measured at the top of the housing, with no air gap)

On my car is a 998 engine...
I have a Fletcher alloy(aluminium?) radiator, unknown age heater hoses. the engine has been chemically cleaned as it was given new bearing shells and thrust bearings. Waterpump and bypass hose were new when I refitted the motor in March.

Apologies for the thread hijack but I feel like I only have one test which is the output voltage of the stabiliser, but the fuel gauge works perfectly so can I rule out the voltage stabiliser?

Kind regards and thanks!

Cal

Edited by cal844, Yesterday, 09:27 PM.


#13 viz139

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Posted Today, 09:36 AM

Two things that will make an engine run hot are timing off and a lean mixture. Your cooling system may be doing its best to cool a hot engine. I had an overheating problem when I switched a leaking water pump with a locally sourced one. Replacing it with the Minispares evo one cured it.






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