Normal Engine Coolant Temperature
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#22
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Thought about that but my local Radio Shack beat Radio Shack Corporate out of business. Found a 100 ohm and 2-320 ohm in the junk box. In parallel that is about twice what I need.
Next town, 20 miles away, has an open RS and a Chinese Buffet . . . and the best pawn shop/gun/reloading store in the area . . . and the wife is quilting with friends in the opposite direction. A day off . . . .
Great thought, wish I did. The plastic cross over pipe was so rotten I tossed it. But it may have read much the same as the new Denso one as I had never measured coolant temp with the IR meter and the Jaguar StupidGuage would not have displayed anything out of sorts.
But the difference has always been since November that the fans run all the time after the car has warmed up with the AC off.
Perhaps Coventry West will provide advice.
Next town, 20 miles away, has an open RS and a Chinese Buffet . . . and the best pawn shop/gun/reloading store in the area . . . and the wife is quilting with friends in the opposite direction. A day off . . . .
Originally Posted by WhiteXKR
Do you still have the original sensor? Perhaps just put that in the new pipe if the old sensor is still good.
Do you still have the original sensor? Perhaps just put that in the new pipe if the old sensor is still good.
But the difference has always been since November that the fans run all the time after the car has warmed up with the AC off.
Perhaps Coventry West will provide advice.
Last edited by test point; 03-27-2015 at 08:01 PM.
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![Embarrassment](https://www.jaguarforums.com/forum/images/smilies/redface.gif)
I have a used one is you want it (free). It is from my 2003 S-type when I changed the front pipe assy. It has same Denso part number BTW.
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I would appreciate the sensor. Maybe 10% variation is within Denso's engineering specs. Or, at least I could document the affects of aftermarket sensors.
I am surprised that you have not run into high temp readings with the RealGauge.
Is there an adjustment on the circuit board to 'tune' the RealGauge?
Just went through my junk box and have things that I had forgotten including a Ford temp sensor but no Jaguar one. Did find a full set of Jaguar valve cover gaskets that I had forgotten about.
I am surprised that you have not run into high temp readings with the RealGauge.
Is there an adjustment on the circuit board to 'tune' the RealGauge?
Just went through my junk box and have things that I had forgotten including a Ford temp sensor but no Jaguar one. Did find a full set of Jaguar valve cover gaskets that I had forgotten about.
Last edited by test point; 03-27-2015 at 08:45 PM.
#25
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Yes, you can set RealGauge to display as you wish through a software calibration procedure I had created for '96-'99 models which have wider tolerances in the instrument cluster assembly http://www.thejagwrangler.com/upload...ration_2.3.pdf . However, that will just mask the issue, since as you know it is definitely not normal for your fans to be running when cruising at modest speeds.
If RealGauge and OBDII are reading the same, they are reading exactly what the temperature sensor sees (unless the ECU has a fault).
I'll send you the sensor. We'll see if that sheds light or adds to the mystery.
If RealGauge and OBDII are reading the same, they are reading exactly what the temperature sensor sees (unless the ECU has a fault).
I'll send you the sensor. We'll see if that sheds light or adds to the mystery.
Last edited by WhiteXKR; 03-27-2015 at 09:19 PM.
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Originally Posted by Bryan at Coventry West;
That's a very odd situation you've got going on there. Normally, when a sensor fails, it fails in a much more noticeable way. It doesn't fail in a predictable linear way, but there's no debating the resistance measurements you got (unless you don't trust your voltmeter?). Take a look at this link here:
RandomExploits
It shows a wider temperature range breakdown for that Denso sensor. Could you tell me if that 30 ohm difference goes across the entire temperature range, or does the difference vary depending on the water temp? If it's the same across the board, I'd almost start leaning toward the hypothesis that some of these Denso sensors are calibrated slightly differently than what they originally had been and that a sensor from an alternate manufacturer might be the way to go. If the resistance difference varies depending on the temperature, then we can take that data and go from there.
RandomExploits
It shows a wider temperature range breakdown for that Denso sensor. Could you tell me if that 30 ohm difference goes across the entire temperature range, or does the difference vary depending on the water temp? If it's the same across the board, I'd almost start leaning toward the hypothesis that some of these Denso sensors are calibrated slightly differently than what they originally had been and that a sensor from an alternate manufacturer might be the way to go. If the resistance difference varies depending on the temperature, then we can take that data and go from there.
. . . . . . Ohms
*C Pub Meas Delta
Boil . . . . 187 TB
92 . . . . .220
90 249 220 29 250
88 263 231 32
86 274 245 29
84 292 263 29
82 309 285 24
80 322 298 24 320
78 342 318 24
76 361 330 31
74 383 358 25
72 407 376 31
70 432 402 30 400
68 460 431 29
66 487 460 27
64 520 490 30
62 555 521 34
60 591 556 35
58 633 596 37
56 681 638 43
54 730 668 62
52 776 720 56
50 833 780 53
48 895 821 74
Generally, it is linear from 60*C/140*F which I would interpret as the thermistor is functioning as designed only reading 30 ohms too low.
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Bryan is sending me another brand of the same sensor to see if that makes any difference.
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Got the sensors from both WhiteXKR and Bryan at Coventry West today and got the DVOM and cooking temp thermostat out.
Steve's OEM used 'S Type' sensor measured 413 ohms at 70*C, 311 ohms at 80*C and 233 ohms at 90*C. Jaguar's specs say 435, 320 and 250 ohms.
Remember, thirty ohms translates to 10*C to the ECM and the decision to operate the fans but the varistors are not exactly linear.
Coventry West's Uro brand sensor was closest at 419, 315 and 246.
Installed the Uro sensor but am seeing operating temperature still in the high 90's on the TORQUE app.
New thermostat next as it is easy. Water pump in hand for the next step.
Remember . . . none of this would be visible with the Jaguar temp gauge. You could drive out of a dealer with the engine running at 100*C and no one would know.
Another reason to explore the RealGauge.
Steve's OEM used 'S Type' sensor measured 413 ohms at 70*C, 311 ohms at 80*C and 233 ohms at 90*C. Jaguar's specs say 435, 320 and 250 ohms.
Remember, thirty ohms translates to 10*C to the ECM and the decision to operate the fans but the varistors are not exactly linear.
Coventry West's Uro brand sensor was closest at 419, 315 and 246.
Installed the Uro sensor but am seeing operating temperature still in the high 90's on the TORQUE app.
New thermostat next as it is easy. Water pump in hand for the next step.
Remember . . . none of this would be visible with the Jaguar temp gauge. You could drive out of a dealer with the engine running at 100*C and no one would know.
Another reason to explore the RealGauge.
Last edited by test point; 04-02-2015 at 08:02 AM.
#31
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The engineered normal temperature has never been determined. With an 84*C thermostat my thought is that that should sorta determine normal.
I just went through all this with my V8 Volvo. It has an 80*C thermostat and stays there or might move up to 84* when the fans come on. Then it cools down to the 80* point and the fans go off.
Today's entertainment has been to evaluate the Jaguar temperature regulation and fan operation with the new sensor installed.
With 18*C/64*F ambient temp the fans come on at 96*C as measured on the OBDII driven TORQUE app. Using the IR thermometer the head temperature is 91*C and the brass body of the sensor measures 74*C. The fans go off at 91*C on the TORQUE reading. The RealGauge reading is correspondingly above the 85* point as identified by the installation instructions.
Since the latest sensor is still a few ohms below the resistance values in the Jaguar table that might account for the differences between the thermostat specs and the measured head temperature. Remember, 30 ohms is 10*C in this section of the varistor's resistance slope.
Also remember that anyone with only the Jaguar idiot temperature gauge would be blissfully unaware of any of this except maybe for the fans running too much.
At least the fans do not run all the time now. In fact I had to run the engine rpm up to get the fan to come on as they never did at idle.
I guess I have to declare the fan problem solved although the measuring tools do not accurately reflect the correct information.
Thanks to Steve at JagRangler and Bryan at Coventry West for helping and putting up with me.
I just went through all this with my V8 Volvo. It has an 80*C thermostat and stays there or might move up to 84* when the fans come on. Then it cools down to the 80* point and the fans go off.
Today's entertainment has been to evaluate the Jaguar temperature regulation and fan operation with the new sensor installed.
With 18*C/64*F ambient temp the fans come on at 96*C as measured on the OBDII driven TORQUE app. Using the IR thermometer the head temperature is 91*C and the brass body of the sensor measures 74*C. The fans go off at 91*C on the TORQUE reading. The RealGauge reading is correspondingly above the 85* point as identified by the installation instructions.
Since the latest sensor is still a few ohms below the resistance values in the Jaguar table that might account for the differences between the thermostat specs and the measured head temperature. Remember, 30 ohms is 10*C in this section of the varistor's resistance slope.
Also remember that anyone with only the Jaguar idiot temperature gauge would be blissfully unaware of any of this except maybe for the fans running too much.
At least the fans do not run all the time now. In fact I had to run the engine rpm up to get the fan to come on as they never did at idle.
I guess I have to declare the fan problem solved although the measuring tools do not accurately reflect the correct information.
Thanks to Steve at JagRangler and Bryan at Coventry West for helping and putting up with me.
Last edited by test point; 04-02-2015 at 09:53 AM.
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#33
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See page 11.4 of http://www.jagrepair.com/images/Trai...ual-9-5-01.pdf for the rated fan switching points.
In my experience, on my XKR, the switching points are 5-7 degrees F higher. It could be a programmed difference on the XKR or just system tolerances.
In my experience, on my XKR, the switching points are 5-7 degrees F higher. It could be a programmed difference on the XKR or just system tolerances.
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