Black_raven Posted April 29 Share Posted April 29 Greetings, Guy, I possess a 2020 GLC 300d, which was taken to Mercedes for repairs owing to coolant loss. The temperature sensor and intercooler were replaced. I received the automobile back, now exhibiting a new malfunction. The coolant loss has ceased; nevertheless, the temperature gauge fluctuates, reaching 90 degrees Celsius before intermittently descending to approximately 70 degrees, then returning to 90 and subsequently lowering again to 70, although it can also maintain stability at times. It appears to be contingent upon the mood. It may occur during a brief trip or an extended continuous voyage. I returned it, and they changed the thermostat; however, the problem persisted. They returned once more and replaced the coolant pump; nevertheless, this did not resolve the issue. They are now asserting that it is typical, a claim I find unconvincing considering it has not exhibited this behaviour previously. What are your thoughts? Quote Link to comment Share on other sites More sharing options...
ElectricEclipse Posted April 29 Share Posted April 29 Temperature fluctuations may occur due to the thermostat's position (open or closed), ambient temperature, airflow through the radiator (which is influenced by speed and the operation of the radiator fan), and engine load; so, some variation is indeed typical. Quote Link to comment Share on other sites More sharing options...
nicebubby8 Posted April 29 Share Posted April 29 It appears that the thermostat is deteriorating. Quote Link to comment Share on other sites More sharing options...
Rudy7831 Posted April 29 Share Posted April 29 Mine does not fluctuate... ever... as it reaches the desired temperature, it remains consistently stable at 90 degrees, with a variance of one or two degrees. This was true for all my recent vehicles. If the stat (which determines the lowest operational temperature) and the fan along with its switch (which determines the peak temperature) are functioning correctly, this is how it should operate. Quote Link to comment Share on other sites More sharing options...
Black_raven Posted April 29 Author Share Posted April 29 I share your understanding that the optimal operating temperature should be maintained at 90 degrees for efficient performance; excessive temperatures may lead to overheating, while insufficient temperatures result in increased fuel consumption to achieve the desired operating temperature. I have possessed this car for only a year, yet it has not exhibited this issue before the repair, which indicates the necessity of reevaluating the previously conducted work. Quote Link to comment Share on other sites More sharing options...
Black_raven Posted April 29 Author Share Posted April 29 Certain variant I concur with a variation of 1 or 2 degrees; nevertheless, this fluctuation involves a decrease of approximately 20 degrees followed by a subsequent increase, occurring consistently on every journey several times. Quote Link to comment Share on other sites More sharing options...
ElectricEclipse Posted April 29 Share Posted April 29 My present vehicle typically operates somewhat around 80 degrees, but in traffic on a sunny day, it can reach approximately 120 degrees, while during winter, it may drop below 80 degrees when driving. Numerous vehicles I own have exhibited this variety, hence it appears pretty usual to me. The majority possess a viscous coupling to operate the fan. Quote Link to comment Share on other sites More sharing options...
CelestialSeeker Posted April 29 Share Posted April 29 That appears to be standard; they possess a configured thermostat and water pump. Temperature decreases following prolonged runs or during rapid acceleration for efficiency purposes. Both of my mercenaries exhibit this behaviour. The previous one had functioned without issues for six years. Quote Link to comment Share on other sites More sharing options...
Black_raven Posted April 29 Author Share Posted April 29 Indeed? Do you imply that it may not have functioned properly before, but is now operating correctly following the repair? Quote Link to comment Share on other sites More sharing options...
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