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The mkiv Supra Owners Club

Strange temperature readings


Smellywelshman

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Hi all,

 

For a couple of weeks now I've been noticing that the temp gauge has been slow to get up to normal running temp. I've just been out for a good 10mile run and all the way back the needle has been at around 1/5th of the way up the gauge as opposed to its normal 'just under half'. Every now and again it would twitch back up to where it should be then drop down again.

 

When I got back I whipped the dash off and checked there wasn't any loose connections (which I couldn't see any). And after refitting the dash I turned the ignition on (without starting the engine) and the gauge was reading fine. I started the engine and revved it a bit and the needle started moving down slowly. Once I revved it over 4k it dropped sharply to the 1/5th of the way up again and stayed there. I turned off the engine for a bit and repeated this again and exactly the same happened!

 

Any one got any ideas as to what could be wrong? There are no warning lights coming on or anything!:search:

 

Thanks

 

Rob...

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I would definately say thermostat. I had this in my MR2, would sit in a traffic jam and the gauge would rise up and read about half, and then as soon as were moving and air was flowing over the car the needle dropped right down almost to the stop. £10 and a new thermostat sorted this. From what I can remember of the MR2's thermostat you can take it off and put it in some hot water and see if it fully opens, might be the same on the Supe.

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No idea where it is on a Supe, only had mine for a little bit, but you should be able to dunk it in warm or hot water and watch it open, if it does then thats great, the next bit to check would be that going from it being fully open in hot water, stick it in some cold and make sure that it completely closes again. Your problem sounds like it is sticking open all the time so getting it hot and then putting it in cold water will tell you if it is this.

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Cheers everybody,

 

I was hoping you would say something like that!!;)

 

Any idea on how much one of these little bad boys goes for from Mr T?

 

Think i've got a brand new one somewhere mate. You can have it if I can find it. :D

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  • 4 weeks later...

Right, update on this.

 

I've now changed the engine coolant temp sensor (including the connector as the wiring was a bit ropey) and put a new thermostat in. aaaaaaaaaaaaaaaaaaand......... its still the same!!:banghead:

 

After running the engine long enough for it to reach normal operating temp the gauge is still at around 1/5th of the way up. If I turn off the engine but keep the ignition on I can see the gauge creeping up to around where it should be, but then if I start the engine again and rev it a bit the needle drops back down to the 1/5th point!!

 

What else could it be?? A mechanic took off my steering rack not long ago to fix some play in it. Is there anything he could have 'knocked'?

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  • 2 weeks later...

But of a bump, but I meant to comment on this thread and forgot...

 

Mine has one this ever since I've had it, the sensors and stat have both also been replaced.... I was meaning to measure the temperature independantly at one point, but never got around to it. The previous owner had noticed it too, and asked on here - again was just advised not to worry about it ;)

 

To put your mind at rest a bit, I've done about 30k on mine like it without a problem :)

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