Range Rover Temp Sender Thread Size?
Discussion
Dr Mike, do bear in mind that water under pressure boils at a higher temperature than water at sea level atmospheric pressure.
So your engine is nowhere near boiling.
My fans kick in at around 90 degrees on the gauge, and mine with the new sensor seems to be pretty accurate.
I have an oil temperature gauge too, and my water temperature seems to mirror the oil temperature on the road.
On a track day my oil temperature rises to around 112-115 degrees, but the water temperature stays around 90 degrees on the new sensor.
Hope this helps.
So your engine is nowhere near boiling.
My fans kick in at around 90 degrees on the gauge, and mine with the new sensor seems to be pretty accurate.
I have an oil temperature gauge too, and my water temperature seems to mirror the oil temperature on the road.
On a track day my oil temperature rises to around 112-115 degrees, but the water temperature stays around 90 degrees on the new sensor.
Hope this helps.
trev4 said:
They do take a bit of getting used to. I had an early start a few weeks ago and happened to look at the gauge after a few miles and it was up at 95deg, as I watched it went back down 65 deg then after a while back up again to 95deg. The next drop it settled at 80deg. Obviously as the thermostat was opening and closing. Normally this time of year I would be lucky to see 50/60deg.
Come to think of it, mine did exactly that as well - rapidly went up to nearly 100°C, then rapidly down and came back up again. I presume the drop is the moment when the thermostat opens, with an influx of cold water from the radiator that hasn’t yet seen the heat of the engine.Unfortunately on that first drive I didn’t have RG connected so I don’t know if the ECU sensor was seeing the same thing. Next time I do a drive from stone cold I’ll have Mrs Oxgreen’s laptop with me and I’ll check.
QBee said:
Dr Mike, do bear in mind that water under pressure boils at a higher temperature than water at sea level atmospheric pressure.
So your engine is nowhere near boiling.
Oh, absolutely!So your engine is nowhere near boiling.
I do wonder whether I could figure out a resistor value that would correct the 3-4° over-read that I’m getting. Does anyone know the characteristics of this sensor well enough to be able to calculate it? Or maybe I could just use a variable resistor to find the right value by trial and error, then replace it with a fixed resistor.
How could I test the performance of the sensor at temperatures above 95°C? I guess I could disconnect my fans - but how hot is it safe to go before I stop the test to avoid warping the heads?
Edited by Dr Mike Oxgreen on Sunday 6th October 08:16
So it looks like the resistance is 44 - 1158 ?
Which way round does it work? Some sensors seem to have a positive coefficient, others negative. If the resistance decreases with higher temperature then I could possibly just add a resistance in series to tune out my over-read.
Which way round does it work? Some sensors seem to have a positive coefficient, others negative. If the resistance decreases with higher temperature then I could possibly just add a resistance in series to tune out my over-read.
Edited by Dr Mike Oxgreen on Sunday 6th October 08:54
I would just accept that it reads slightly high.
Variable resistors can cause more problems than they cure (I bought one, and it worked brilliantly up to 85 degrees, but never went any higher, even though i could hear the fans going full blast after ten laps of Snetterton on a hot day).
Many of us have had the gauge reading 100+ degrees on a hot day stuck in traffic, when the fan connections had got corroded or the otter switch had failed, without doing any detectable damage, so your idea of disconnecting the fans and taking it up to 100 degrees for a few seconds, starting from cold, should be less of a risk than said stuck in traffic incidents.
Variable resistors can cause more problems than they cure (I bought one, and it worked brilliantly up to 85 degrees, but never went any higher, even though i could hear the fans going full blast after ten laps of Snetterton on a hot day).
Many of us have had the gauge reading 100+ degrees on a hot day stuck in traffic, when the fan connections had got corroded or the otter switch had failed, without doing any detectable damage, so your idea of disconnecting the fans and taking it up to 100 degrees for a few seconds, starting from cold, should be less of a risk than said stuck in traffic incidents.
Why are people getting so upset about a few degrees difference. Personally I'm amazed anyone can read the gauge that accurately whilst driving. This is a variable temperature being read by two different technologies with error bands due to mass production of the senders, mass production of the gauge mechanisms being powered by an unstable voltage supply. Don't forget you are only measuring a single point in a system that has localised heating and localised cooling sectors. Who cares if their coolant measured in one section of a heating and cooling circuit is 3 or 4 degrees different between two measuring systems.
The issue here is to correct the problem caused by TVR fitting their sender in a dead space. This fix also positions the gauge sender close to the ECU sender which means the gauge reading should be reasonably similar to the ECU.
The issue here is to correct the problem caused by TVR fitting their sender in a dead space. This fix also positions the gauge sender close to the ECU sender which means the gauge reading should be reasonably similar to the ECU.
Well I’ve just done a stationary* test from stone cold, with Rovergauge running. The results are interesting, and somewhat more promising than my first experiments.
During the initial warm-up the gauge was reading about 5°C lower than Rovergauge. Hard to know whether this was an under-read or merely a thermal lag in the sensor; I’m suspecting the latter.
As we approached the 90°C mark, the two temperatures got closer and closer, and started agreeing very closely indeed. Then (I presume) the thermostat opened and both temperatures plummeted to about 80°C. Both temperatures then climbed slowly and steadily, agreeing very closely, until the fans kicked in with both temperatures showing about 93°C or thereabouts. From this point onwards, both temperatures continued to agree to within a gnat’s cock, with none of the 3-4°C discrepancy I was seeing yesterday.
So is it possible that these sensors need a couple of thermal cycles before they “bed in” and start giving their proper readings? Or maybe a couple of expansion cycles have caused the sensor to make a better electrical contact with the block?
Anyway, I’m now hopeful that I might see the same degree of accuracy that COG reported. I’ll do another road test soon.
* I can’t do a road test because Mrs Oxgreen and I have spent the early afternoon in the Red Lion.
During the initial warm-up the gauge was reading about 5°C lower than Rovergauge. Hard to know whether this was an under-read or merely a thermal lag in the sensor; I’m suspecting the latter.
As we approached the 90°C mark, the two temperatures got closer and closer, and started agreeing very closely indeed. Then (I presume) the thermostat opened and both temperatures plummeted to about 80°C. Both temperatures then climbed slowly and steadily, agreeing very closely, until the fans kicked in with both temperatures showing about 93°C or thereabouts. From this point onwards, both temperatures continued to agree to within a gnat’s cock, with none of the 3-4°C discrepancy I was seeing yesterday.
So is it possible that these sensors need a couple of thermal cycles before they “bed in” and start giving their proper readings? Or maybe a couple of expansion cycles have caused the sensor to make a better electrical contact with the block?
Anyway, I’m now hopeful that I might see the same degree of accuracy that COG reported. I’ll do another road test soon.
* I can’t do a road test because Mrs Oxgreen and I have spent the early afternoon in the Red Lion.
Edited by Dr Mike Oxgreen on Sunday 6th October 17:29
As far as I can tell, mine is spot on.
For the first time in over 40,000 TVR miles I am confident of the actual engine water temperature.
Bear in mind three things Daz:
1. Most modern road cars these days only have three settings on the temperature gauge.
They read cold, 90 or f
ked. The needle actually never sits anywhere in between.
They are far less "accurate" than the TVR gauges.
2. The only reading that matters is too hot.
3. You barely do enough miles in a year to open the thermostat....never mind overheat it.
For the first time in over 40,000 TVR miles I am confident of the actual engine water temperature.
Bear in mind three things Daz:
1. Most modern road cars these days only have three settings on the temperature gauge.
They read cold, 90 or f
ked. The needle actually never sits anywhere in between. They are far less "accurate" than the TVR gauges.
2. The only reading that matters is too hot.
3. You barely do enough miles in a year to open the thermostat....never mind overheat it.
jojackson4 said:
It is there is a bit of drilling and tapping
But nothing hard
So you tapped it .. where did the bits go ? You stuck a plug in the old hole , wouldn't it have been easier to spend a few quid on a new one But nothing hard
And in my opinion the TVR variable resistor sensor doesn't match the gauge very well … look at Steve Heath Bible.
Edited by glow worm on Sunday 6th October 19:56
glow worm said:
SILICONEKID 357HP said:
What is the optimum temperature for an engine to run at and at what temp is it to hot ?
Optimum 90 Degrees I thought … 100+ I get concerned the fans aren't working … 110 I'd stopEdited by glow worm on Sunday 6th October 19:41
On track days, oil at 115 degrees, turbo busy doing what turbos do, my water never gets above about 92-95 as the fans are doing their job despite my best efforts to over power them.
So a normally aspirated engine on the road (where you don't have your foot flat to the boards 75% of the time) should stay under 90 on the gauge, the only exception being crawling in traffic with no airflow on a hot day, when you would expect the fans to take over and keep the temperature down to 90 degrees
Well I was impressed with COG find so thought why not 
so purchased 2 and yes gauge climbed in a more linear movement and seemed more responsive when up to temp i.e you could see obvious changes with fans ON/OFF ...................................................................... ....................Now the bad bit .... glancing at the gauge after a coastal blast with lots of high RPM/load action and then seeing this ended up hitting a gauge indicated 120c on way home (normally sits around 80) fortunately oil pressure normal inc oil temps and no rock hard hoses or vomiting coolant but not before I pulled over having heart palpitations 
just a failed temp sender fortunately after just 1 weeks use sadly 
knew I would have to send off my findings to CAI so wrote down some comparison figures with a temp probe and some hot water , my spare as been fine since , slightly annoying seeing as the LR with a resistor mod is over 20 YO 
guess these things happen , and CAI sent another one out no trouble .............. ............................................................ 
so purchased 2 and yes gauge climbed in a more linear movement and seemed more responsive when up to temp i.e you could see obvious changes with fans ON/OFF ...................................................................... ....................Now the bad bit .... glancing at the gauge after a coastal blast with lots of high RPM/load action and then seeing this ended up hitting a gauge indicated 120c on way home (normally sits around 80) fortunately oil pressure normal inc oil temps and no rock hard hoses or vomiting coolant but not before I pulled over having heart palpitations just a failed temp sender fortunately after just 1 weeks use sadly knew I would have to send off my findings to CAI so wrote down some comparison figures with a temp probe and some hot water , my spare as been fine since , slightly annoying seeing as the LR with a resistor mod is over 20 YO guess these things happen , and CAI sent another one out no trouble .............. ............................................................ Edited by Sardonicus on Sunday 6th October 23:27
Sardonicus said:
Well I was impressed with COG find so thought why not so purchased 2 and yes gauge climbed in a more linear movement and seemed more responsive when up to temp i.e you could see obvious changes with fans ON/OFF.
Now the bad bit .... glancing at the gauge after a coastal blast with lots of high RPM/load action and then seeing this ended up hitting a gauge indicated 120c on way home (normally sits around 80) fortunately oil pressure normal inc oil temps and no rock hard hoses or vomiting coolant but not before I pulled over having heart palpitations
I think you've just been unlucky there Simon so purchased 2 and yes gauge climbed in a more linear movement and seemed more responsive when up to temp i.e you could see obvious changes with fans ON/OFF.Now the bad bit .... glancing at the gauge after a coastal blast with lots of high RPM/load action and then seeing this
ended up hitting a gauge indicated 120c on way home (normally sits around 80) fortunately oil pressure normal inc oil temps and no rock hard hoses or vomiting coolant but not before I pulled over having heart palpitations , I took advise directly from Caerbont on this who made the TVR gauges in the first place and know a thing or two about gauge to sender matching, also no one else that I'm aware of has suffered such a massive over read situation? While I'm sure you'll tell me your system was well bled, I have to say if I could change anything about the TT6811-03 sender I'd make it longer.
If there's a pocket of steam in the head there's every likelihood the sender will read high, being shorter than the Range Rover sender this is more likely as it may well sit above the coolant level where the Range Rover sender will still be partially submerged.
I remain very happy with my TT6811-03 sender its a definite improvement over the resistor mod on the Range Rover sender as I discovered that idea simply can't be trusted to warn the driver of an overheating situation making it worse than useless. As reported when I published my test results I did experience some spikes early on but they have since disappeared and were very temporary even when they did take place. During the warm phase up the gauge on few occasions briefly overshot my Canems temp reading but soon returned to normal within seconds, and this has not happened for well over a month now so it seems my sender has completely settled down.
On a separate and I believe unrelated note yesterday I bled my cooling system as for some time my offside rad fan has been blowing cold air, even on hot days with the car up to full temp, I used the big funnel in the swirl pot method to create a nice big header of high up coolant to purge out any air but the offside fan was still blowing cold indicating poor flow across what is of course a cross flow rad.
so I reverted to force filling the rad itself at the bleed screw in the offside rad tank which did the trick nicely, to be honest this is where I would normally start the bleeding process anyway before moving my way higher up the system. My point being a header fill at the swirl pot is never going to fill the rad and its tanks so always start at the rad bleed screw before working your way up, my rad fill came with a lot of air followed by a final surge up that completely back filled the empty funnel with quite silty looking coolant so when the spring comes around again and it's time to refresh my coolant with new antifreeze I'll be giving the entire system a back flush.
Anyway for now it's all good with a nice 50/50 mix I only added when I fitted my new vaporiser so it's good to cover this winter, the nearside fan now blows hot air proving the rad is flowing from n/s to o/s just as it should, the heater runs super hot, and there's none of the tell tale gurgles from the passenger footwell (the heater) that experience tells me its time to bleed the system.
I'll end by saying it's quite clear with the TT6811-03 sender being quite a bit shorter it's especially important to make sure your coolant system is perfectly bled
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