 | Home > Technical > Defender 90 High water temperature. |
 
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| Cubflyer Member Since: 25 Sep 2021 Location: Suffolk Posts: 278   
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Hi folk ... maybe someone can shine a light on this issue please.
I've a Defender 90 TDI300 (1994) Firstly, when I turn the ignition on (despite weeks of not using) the temperature needle shoots straight to just under half way. After driving for only 25/30 miles the temperature edges into the edge of the red and this is at a maximum speed of 60 mph ... If I push to 65mph the needle continues well into the red. Someone mentioned it could be that the viscous fan may need changing?, that has been done with NO change! Thanks in anticipation John 2010 Defender 90 300Tdi CW (White/1994) 2021 Defender 90 300Tdi SW (Blue/1994) |
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8th Sep 2023 8:05pm |
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| Jabberwocky Member Since: 27 Oct 2021 Location: Luxembourg Posts: 223 
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Surely the sensor is shot? Or the gauge?
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8th Sep 2023 9:34pm |
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| Cubflyer Member Since: 25 Sep 2021 Location: Suffolk Posts: 278
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Thanks for the reply ... Maybe?? not that straight forward.
I have a new sensor(s) ... just need to know which one as there are two types (Green or Black) 2010 Defender 90 300Tdi CW (White/1994) 2021 Defender 90 300Tdi SW (Blue/1994) |
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9th Sep 2023 9:00am |
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| landy andy Member Since: 15 Feb 2009 Location: Ware, Herts Posts: 5732 
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There must be a sender, wiring, or gauge fault, as it shouldn’t go straight to mid point.
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9th Sep 2023 9:07am |
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| Cubflyer Member Since: 25 Sep 2021 Location: Suffolk Posts: 278
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Thanks Andy for the quick reply ... I'll try the "Sender/Sensor" first
 2010 Defender 90 300Tdi CW (White/1994)
2021 Defender 90 300Tdi SW (Blue/1994) |
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9th Sep 2023 9:10am |
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| TexasRover Member Since: 24 Nov 2022 Location: Paris Posts: 1089  
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Also buy a cheapo infrared thermometer at Amazon, then you check check the temperature of your engine which takes away one concern (probably)
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9th Sep 2023 1:53pm |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6611 
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If it’s going to halfway with a cold engine this is a sensor issue.
Has it always done it or just started? The correct sensor for a 300 Tdi Defender is AMR3321, a Disco sensor is different and would cause this problem. What could also cause this is a poor gauge earth, check the integrity of the black wire(s) on the ring terminal on the back, and the tightness of the nut holding the ring on.  1988 90 Td5 NAS soft top
2015 D90 XS SW |
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9th Sep 2023 2:00pm |
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| Cubflyer Member Since: 25 Sep 2021 Location: Suffolk Posts: 278
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Hi Martin ... I've had it two years and it's always indicated warm from the very start. I've got a new sender now so just need to try the new one.
What it has not always done is edge into the red (H) at 60mph. I've always been able to travel long distances at 65 mph with no issue. Thank you John 2010 Defender 90 300Tdi CW (White/1994) 2021 Defender 90 300Tdi SW (Blue/1994) |
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9th Sep 2023 3:12pm |
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| Cubflyer Member Since: 25 Sep 2021 Location: Suffolk Posts: 278
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Thanks Andy ... I'll do that! 2010 Defender 90 300Tdi CW (White/1994)
2021 Defender 90 300Tdi SW (Blue/1994) |
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9th Sep 2023 3:13pm |
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| landy andy Member Since: 15 Feb 2009 Location: Ware, Herts Posts: 5732
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Would you have had a discovery engine fitted at some point?
If it’s now running hotter than previous it may be worth giving the system a flush, fitting a new thermostat, and then new coolant. Do you get a good flow of water into the header tank when you give the engine a rev? |
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9th Sep 2023 3:33pm |
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| Cubflyer Member Since: 25 Sep 2021 Location: Suffolk Posts: 278
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Hi Andy
No mods done to it. I bought it from "One careful lady owner" who'd has it from new. I did a complete flush ayear ago but I guess a new thermostat certainly wouldn't break the bank. Sounds like a head under the bonnet this week 
Thanks for all your much appreciated comments! I'll report back John 2010 Defender 90 300Tdi CW (White/1994) 2021 Defender 90 300Tdi SW (Blue/1994) |
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9th Sep 2023 7:18pm |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6611
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Check the colour of the ring around the coolant sensor bullet, should be black for a Defender. If it’s a Disco sender it will be green.
1988 90 Td5 NAS soft top
2015 D90 XS SW |
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9th Sep 2023 7:50pm |
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| Cubflyer Member Since: 25 Sep 2021 Location: Suffolk Posts: 278
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Hi Martin ... It's black as is the new one
 2010 Defender 90 300Tdi CW (White/1994)
2021 Defender 90 300Tdi SW (Blue/1994) |
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9th Sep 2023 7:56pm |
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| Cubflyer Member Since: 25 Sep 2021 Location: Suffolk Posts: 278
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Hi folk ... Just like to thank all of you that replied - much appreciated!
Fitted the new sender this afternoon and the gauge error is fixed (It had a GREEN Disco) sender fitted 
One point ... does any know where I can get a repacement "Push-on" connector, mine is a guess original and the rubber boot has perrished. As for the high temperature readings, I guess I need to give it a good run to see if the new sensor has sorted it out before I start changing the thermostat or gauge. Thanks again John 2010 Defender 90 300Tdi CW (White/1994) 2021 Defender 90 300Tdi SW (Blue/1994) |
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17th Sep 2023 4:30pm |
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