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So when monitoring the coolant temperature with Torque after my latest drain & fill, I noticed that the temperature swings significantly. It ranges from 80C to 100C. I think the Torque reading ties with my Autel MP808; both show similar numbers, if not simultaneously.
The dash readout apparently lies, sitting at 90 the whole time.
I made the mistake of installing a generic thermostat a while back. Before I go to the trouble of swapping it with a good quality one, would one of y'all be willing to monitor your temperature during a typical drive? If others' motors do the same, I probably won't bother swapping, but gee - this seems significant.
Last edited by eric_in_sd; Oct 10, 2023 at 09:24 AM.
So when monitoring the coolant temperature with Torque after my latest drain & fill, I noticed that the temperature swings significantly. It ranges from 80C to 220C. I think the Torque reading ties with my Autel MP808; both show similar numbers, if not simultaneously.
The dash readout apparently lies, sitting at 90 the whole time.
I made the mistake of installing a generic thermostat a while back. Before I go to the trouble of swapping it with a good quality one, would one of y'all be willing to monitor your temperature during a typical drive? If others' motors do the same, I probably won't bother swapping, but gee - this seems significant.
mine is rock steady on the display at round 82c in summer, slightly lower in cold months. Never any fluctuations.
mine is rock steady on the display at round 82c in summer, slightly lower in cold months. Never any fluctuations.
Right, my dash display is steady, but when I query the ECU it reports swinging from 80C to 100C. (Edit I was putting in the F reading; I have Torque on Celsius and my Autel on Fahrenheit.)
You feel like monitoring it with Torque (or whatever) whilst you do a drive?
Last edited by eric_in_sd; Oct 10, 2023 at 09:24 AM.
I don’t have torque unfortunately, but I do have xentry…but it’s a bit cumbersome.
I would think that if your dash display is rocksteady, that’s the ground truth right there, he might be falling victim to some poor connection in your OBD port.
So when monitoring the coolant temperature with Torque after my latest drain & fill, I noticed that the temperature swings significantly. It ranges from 80C to 220C. I think the Torque reading ties with my Autel MP808; both show similar numbers, if not simultaneously.
The dash readout apparently lies, sitting at 90 the whole time.
I made the mistake of installing a generic thermostat a while back. Before I go to the trouble of swapping it with a good quality one, would one of y'all be willing to monitor your temperature during a typical drive? If others' motors do the same, I probably won't bother swapping, but gee - this seems significant.
220* Celsius? That can't be right. That is way WAY too high. I don't see how the coolant could even get to that temp without bad things happening. I think the Torque thing is wrong. Besides, you'd also see the dash gauge rising, which it is not.
Concerning the 90*C you're seeing... if it's like my '97 528, there is a buffer built in so people don't complain about "Why is my temperature gauge fluctuating - it shouldn't - I want it fixed". There's nothing wrong with temp's fluctuating - that's normal (within reason, of course). I found a that car had a 50*F buffer built in when monitoring it with a scantool (there was an issue - which is why it was fluctuating that 50*F plus). Meaning, it wouldn't move off of "normal" until the temp rose at least 50*F. But back to your issue, even if it had a buffer, it would have moved WELL before you saw 200*C... and that brings us back to something weird with that Torque.
There's a possibility that the 220*C IS the correct temp that the sensor is reading... but not a "true" reading. Especially if the temp reading is fluctuating very quickly. That can be explained by an air pocket. The temperature in a pocket of air will rise very, very quickly.
If there is more than one sensor (one that feeds that the gauge and one that feeds the computer... which is what the Torque will see), that could explain it. Now, this last part... about the two sensors... I honestly don't know if your engien has two sensors. There are some engines that do - I just have no idea if yours does. But it would certainly explain things.
On the other hand, let's say there's only one sensor - and going on the assumption that the temp swings very rapidly... there's still a possible explanation within the air pocket discussion: The "algorithm" that the computer uses to feed the dash gauge is not exceeded by the amount of time that the temp is reading 220*C. Meaning, the air pocket dissipates faster than the time allowed by the algorithm before the computer directs the dash gauge to change.
Note: I'm typing all of this after two rum 'n cokes.... so it may not make any sense tomorrow morning
220* Celsius? That can't be right. That is way WAY too high. I don't see how the coolant could even get to that temp without bad things happening. I think the Torque thing is wrong. Besides, you'd also see the dash gauge rising, which it is not.
Concerning the 90*C you're seeing... if it's like my '97 528, there is a buffer built in so people don't complain about "Why is my temperature gauge fluctuating - it shouldn't - I want it fixed". There's nothing wrong with temp's fluctuating - that's normal (within reason, of course). I found a that car had a 50*F buffer built in when monitoring it with a scantool (there was an issue - which is why it was fluctuating that 50*F plus). Meaning, it wouldn't move off of "normal" until the temp rose at least 50*F. But back to your issue, even if it had a buffer, it would have moved WELL before you saw 200*C... and that brings us back to something weird with that Torque.
Whoops, I am commingling Celsius and Fahrenheit. Sorry. It is 80C to 100C. I saw 220F on my Autel, which is set to degrees F. And it changes slowly enough to make me think it is an accurate reading.
The thermostat is designed to open at 212. Based on this, the dash display is implicitly misleading.
I don’t have torque unfortunately, but I do have xentry…but it’s a bit cumbersome.
I would think that if your dash display is rocksteady, that’s the ground truth right there, he might be falling victim to some poor connection in your OBD port.
I'm pretty sure the dash display is purposefully damped so as not to worry the customers. Given that the "miles remaining on gas in tank" display defaults to a drawing of a car at a gas pump at a level of about one gallon, this would not surprise me.
I'll have to check how the dash display correlates with what Torque reports from the ECU during warmup. I am confident Torque is reporting honestly; the numbers are not wild and do not change abruptly. They also tie to what my Autel reports.
I'm still wondering if the 20C temperature range is normal. Possibly there simply is enough air flow across the motor to cool it below the thermostat opening point of 212. Or maybe the thermostat's action is not good; once it opens, it is sticky on the closing. Which is why I am wondering whether others see the same behavior.
Maybe I should just change the thermostat. Wouldn't be that hard to do. I'm pretty good at draining and refilling the coolant by now.
Whoops, I am commingling Celsius and Fahrenheit. Sorry. It is 80C to 100C. I saw 220F on my Autel, which is set to degrees F. And it changes slowly enough to make me think it is an accurate reading.
The thermostat is designed to open at 212. Based on this, the dash display is implicitly misleading.
OK, then it sounds like it's just a buffer as I was originally thinking.
I'm not surprised at the 220*, either. A t-stat isn't fully opened till it's rated temp - which means it's reasonable to think that temps can continue to rise a bit before cooling down.
220* Celsius? That can't be right. That is way WAY too high. I don't see how the coolant could even get to that temp without bad things happening. I think the Torque thing is wrong. Besides, you'd also see the dash gauge rising, which it is not.
Concerning the 90*C you're seeing... if it's like my '97 528, there is a buffer built in so people don't complain about "Why is my temperature gauge fluctuating - it shouldn't - I want it fixed". There's nothing wrong with temp's fluctuating - that's normal (within reason, of course). I found a that car had a 50*F buffer built in when monitoring it with a scantool (there was an issue - which is why it was fluctuating that 50*F plus). Meaning, it wouldn't move off of "normal" until the temp rose at least 50*F. But back to your issue, even if it had a buffer, it would have moved WELL before you saw 200*C... and that brings us back to something weird with that Torque.
I would have to agree. It's likely the gauge would report a moving average, rather than instant readings that would frustrate/worry most drivers. I had an older Mini with a digital fuel range gauge that wasn't (sufficiently) buffered and it was basically useless as the range could read anywhere from 5 to 50 miles, depending on if I was going up or down hill - and I lived in a mountainous area. Imagine watching a needle gauge - whether electric or mechanical - doing that.
OK, then it sounds like it's just a buffer as I was originally thinking.
I'm not surprised at the 220*, either. A t-stat isn't fully opened till it's rated temp - which means it's reasonable to think that temps can continue to rise a bit before cooling down.
It could well be a buffer.
The display doesn't bother me as much as the question whether the range 80-100C is normal behavior with a good quality thermostat.
FYI, this thermostat starts opening at 212. Hence it should vary in a small range above that, the size of the range depending on the ratio of the response to temperature. Why it is below that point is the question.
Coolant temps will always move around. It can never be an exact number, too many "moving parts" in the equation. Just sitting still in traffic will raise your temps a little, then you start to move forward and the temps will go back down a bit. Heavy load going uphill will be higher than just coasting downhill.
As someone stated, most modern vehicles will have a "buffer circuit" built in so the dash temps stay in a set point, unless things get too hot or cold.
I use torque app. The temp is solid and stays the same 85C once it reaches operating temperatures. Even revving up just changes it by 1-2 degrees. It has 118K miles now and coolant has never been changed since 2016 (79K miles). I doubt it was ever changed before.
I use torque app. The temp is solid and stays the same 85C once it reaches operating temperatures. Even revving up just changes it by 1-2 degrees. It has 118K miles now and coolant has never been changed since 2016 (79K miles). I doubt it was ever changed before.
Do you have a lower t-stat in there that the gauge reads lower than the rest of ours?
FYI, revving is not a very good test - in some cases, it will actually lower the temp. When you rev it, there's no load on the engine, yet the coolant is circulating faster.
Have you used the Torque app while driving - and going up hills, etc?
I was wondering why the thermostat had multiple wires going to it. Not just two for the temperature sensor, but two for the "wax motor" heater: The ECU nudges the thermostat more open as needed.
Note this suggests if you disconnect the heater, the thermostat might run hotter all the time.
Last edited by eric_in_sd; Oct 13, 2023 at 11:10 AM.
Note that the dash gauge functions somewhat better than an idiot light. It displays 90C as long as the temperature is conforming to the map. MB probably reasonably guessed that people would get nervous seeing the temp swing from 80 to 100C and back.
Note that the dash gauge functions somewhat better than an idiot light. It displays 90C as long as the temperature is conforming to the map. MB probably reasonably guessed that people would get nervous seeing the temp swing from 80 to 100C and back.
And then they might start a thread on a forum about it...
But seriously, nice find with that bar graph, Eric - very interesting to read.
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