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Coolant temperature fluctuation ?

2598 Views 34 Replies 10 Participants Last post by  njacobsen, 
njacobsen
I have been driving with the Coolant Temperature digital readout displayed on the DIC of my 2020 3.6L XT5 for the past 6 months.

The thermostat is 194* and I expect the operating temperature should stay close to that. Mine, however, reaches 190-192 and then in a short amount of times, less than a mile, drops as low as 176 and then hovers around 180. It rarely climbs to the high 180's and then drops back down to 180 or less.

Curious what others are seeing?
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Welcome to club unhappy owner Cadillac!
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Excalibur
ALPAN said:
Welcome to club unhappy owner Cadillac!
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That was unhelpful regarding his question, and You're making a wild presumption - where did he say he was unhappy with his Cadi.
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njacobsen said:
I have been driving with the Coolant Temperature digital readout displayed on the DIC of my 2020 3.6L XT5 for the past 6 months.

The thermostat is 194* and I expect the operating temperature should stay close to that. Mine, however, reaches 190-192 and then in a short amount of times, less than a mile, drops as low as 176 and then hovers around 180. It rarely climbs to the high 180's and then drops back down to 180 or less.

Curious what others are seeing?
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I will display mine in the DIC today and report back later.
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UberCaddy
I've been wondering about that. I haven't checked the DIC, but my temp gauge is below the middle area. I'm used to the temp gauge running in the middle of the gauge range. I'll check the DIC next time...if I remember! 😁
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UberCaddy said:
I've been wondering about that. I haven't checked the DIC, but my temp gauge is below the middle area. I'm used to the temp gauge running in the middle of the gauge range. I'll check the DIC next time...if I remember! 😁
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The temp gauge running a bit below the middle area is normal.
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njacobsen
ALPAN said:
Welcome to club unhappy owner Cadillac!
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Far from the truth...I am very happy with my 2020 XT5...best car I have ever owned.

Your sarcastic comments do not add to our discussions.
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njacobsen
The reason for the question is I am curious if the readings I see are a precursor to thermostat failure. Or, do all of the thermostat failures we see have a root cause other than the actual thermostat?

My previous 2017 Platinum had a gauge display which I really liked. One of the gauges was coolant temperature which would climb normally during warmup until it reached 210* and stay there. Looking back, was that accurate? I am beginning to doubt it was. I convinced my dealer to change the thermostat in my 2020 because I saw it dropping to the vicinity of 180* and told him at the time the 2017 always ran at 210 and he said that is too hot. I never looked for the digital display on that 2017 because I was content 210 was proper.

My Corvette similarly climbs to 220* and stays there. When I looked a a different digital display, the temperature is in the mid 190s, sometimes to 200.

We cannot be content with the gauges that are normally displayed because the engineers seem to be giving us a display to be content.

The question is, what is the normal actual operating temperature range?

I do not have any codes set during these fluctuations, so the control modules must be content with the coolant range of temperatures during operation.
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Submariner409
"Normal" operating temp varies with engine and emissions settings. MOST modern engines will run normally between 190 to 210 degrees at all times. The 'stats are set to begin opening at about 185 and be fully open at 205. Warmup emissions loop change occurs at around 155 to 170 degrees depending on ambient air temps and O2 sensor activation.

A 'stat that begins opening at 185 indicated then allows temp to fall below that is most likely hanging open and not moving in order to maintain coolant temp. There's a sealed wax pellet in the brass chamber that expands and contracts with temp changes, moving the valve plate more or less open. If that system leaks or is "sticky" then the 'stat is toast.

Thermostat homework -


Typical 'stat construction - The lower spring side is in the block/head flow area and is acted upon by warming coolant; the top side sends coolant to the radiator.


Headgear Automotive lighting Automotive wheel system Auto part Jewellery
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E
Another good explanation, thx. And this place has been a great source of knowledge and consequential retrospect. So a big shout out to all those that truly seem to want to contribute to our Cadillac family. Well done.
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njacobsen
Curious why the thermostat housing and coolant tube needs to be changed along with the thermostat on the LGX in the XT5? Seems to be a needless additional cost for a normally inexpensive item.
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Some sort of non-replaceable sealant/gasket?
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njacobsen
It appears to be a specially designed thermostat:
Bicycle part Tool Nickel Auto part Metal
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njacobsen
Better picture of the integrated thermostat:
Automotive lighting Font Metal Nickel Fashion accessory
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Njacobsen's description of his coolant temperature is exactly what I experienced twice with my XT6(same LGX V-6 engine as the XT5). Car ran fine, but heater output was poor, and dash display would show 175-185, occasionally 190 for only a few seconds. Eventually I convinced dealer to replace thermostat, coolant temp. was around 190-195 tje rest of winter of 2021-2022. When it recently got cold outside, heater was again inadequate, temp again never going above 180 except for just a few seconds. Another new thermostat was installed, car ran at 194-204 after warmup.
Apparently a lot of the thermostats are of dubious quality, so I believe a new thermostat is what yours needs, and just hope the new one is a permanent fix.
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E
Interesting how large it is compared to the traditional stat in the previous pic. Seems like it's 'pressed' into the tube which would explain why it has to be changed along with the stat.
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njacobsen said:
I have been driving with the Coolant Temperature digital readout displayed on the DIC of my 2020 3.6L XT5 for the past 6 months.

The thermostat is 194* and I expect the operating temperature should stay close to that. Mine, however, reaches 190-192 and then in a short amount of times, less than a mile, drops as low as 176 and then hovers around 180. It rarely climbs to the high 180's and then drops back down to 180 or less.

Curious what others are seeing?
Click to expand...
Checked mine today and after the engine warmed up and 4 bars were showing on the display gauge the temp. readout was around 190* but fluctuated between as low as 180* (not below) and as high as upper 190's* and varied between those temp. ranges. Even with those fluctuations the 4 bars still showed and never went down to 3 bars.
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njacobsen
When mine drops to 180*, the bars on the temp gauge drop from 4 or 3. The fourth does not come back until the temperature reaches 183* or higher. After the initial warmup, my temperature gauge is at 3 bars 50% of the time or greater. I have not been on a drive of 2 hours or longer in at least 6 months.
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njacobsen said:
When mine drops to 180*, the bars on the temp gauge drop from 4 or 3. The fourth does not come back until the temperature reaches 183* or higher. After the initial warmup, my temperature gauge is at 3 bars 50% of the time or greater. I have not been on a drive of 2 hours or longer in at least 6 months.
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If my temp is showing 180* it is also showing 4 bars. After my initial warmup I show 4 bars all the time. It does not go back to 3 bars to my knowledge after warmup unless I never noticed it but I don't think it has. I don't really know how normal or abnormal the temperature fluctuations are as I observed today as I never actually paid attention to the temp readout. I've always just looked at the displayed number of bars on the gauge.
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njacobsen said:
I have been driving with the Coolant Temperature digital readout displayed on the DIC of my 2020 3.6L XT5 for the past 6 months.

The thermostat is 194* and I expect the operating temperature should stay close to that. Mine, however, reaches 190-192 and then in a short amount of times, less than a mile, drops as low as 176 and then hovers around 180. It rarely climbs to the high 180's and then drops back down to 180 or less.

Curious what others are seeing?
Click to expand...
I just happened to look at my temp gauge (2017 platinum) yesterday and it was at 210*.

I’ll check it again today.
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