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Ontdekker



Member Since: 25 Nov 2009
Location: Centurion
Posts: 11
South Africa 2010 Defender 110 Puma 2.4 CSW Chawton White
Water temperature Vs CHT
I have a madman installed that reads the water temperature. I also have a Ultra Gauge that reads cylinder head temperature from the ECU. I have noticed at times that the CHT is 6 degrees colder than the madman reading at highway speeds. The madman temperature is steady and does not fluctuate much and I have no reason to suspect anything wrong with this. CHT reading fluctuates somewhat and is always equal to or lower than the water reading. Just curious, should one expect cylinder head temperature to be higher than the water temperature, and should it track the water temperature changes closely?
Post #502498 9th Feb 2016 7:01am
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o4dn



Member Since: 08 Jan 2010
Location: South West
Posts: 549
France 2009 Defender 90 Puma 2.4 SW Alaska White
Funny, I had the opposite reading using my (highly suspicious) "formula" for the Scanguage described here:

http://www.defender2.net/forum/post151519.html#151519

Granted, this is prone to all sort of rounding errors obviously... Out of curiosity, what's your reading of the CHT under normal driving conditions, and under load?

Edit: Forgot to mention, my reading of the CHT fluctuates quite a lot. “A Land Rover immobilized is a moral defeat for the driver and bad publicity for the vehicle, […] it's up to you to do justice to your Land Rover!” - Land Rover Driving Technique.
--
2009 2.4 Puma Defender 90 SW
1979 Land Rover Series 3 88"
Post #502519 9th Feb 2016 8:44am
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hornet



Member Since: 04 Jan 2010
Location: Western Europe
Posts: 362
Ontdekker you are right, this may be caused by tolerances/offsets of the sensors caused through wiring. What differences do you have, about 5K? CHT measures headtemperature, not temperature of coolant which is done by ECT-Sensor.

But: Thermostat starts to open @ 82C and is fully open @ 92C. Motorthermostat (in waterpump) opens @ 88C, and thermostat for engine cooling opens @ 75C plusminus 2C.
Post #502582 9th Feb 2016 11:26am
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Ontdekker



Member Since: 25 Nov 2009
Location: Centurion
Posts: 11
South Africa 2010 Defender 110 Puma 2.4 CSW Chawton White
Re: Water temperature Vs CHT
At cruising speed the temperature is between 88 and 93 degrees Celsius on a typical 25 degrees Celsius day. What I observe is that when slowing down from a drive or on a downhill the CHT drops quite rapidly but water temperature remains more or less constant and this is when I observe up to a 6 degree difference at times. So I was wandering about this and whether the CHT gauge is functioning properly.
Post #503377 11th Feb 2016 8:46am
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