joshg1001

So I know the avg operating temperature stays above 80 but below 100 degrees.

However, I have been making long distance trips lately on my car, about 1.5 hours of non stop highway driving. Sometimes on the middle of the trip, it will dip to a little under 80, and then back up to above 80 (like normal). I have seen this many times.

Anybody else see this or might there be something wrong?

I have never owned a car that had the engine temperature drop even when fully warmed up

Stone2486

well when you are on the highway there is a larger amount of airflow going through the radiator. this cools the engine more efficiently at highway speeds. i have also noticed the same thing with my car when cruising about 65-75mph on the highway.

Peabody

You don't ever have to worry about your engine running too cold (once it is warmed up). Just worry about runaway heating.

Carsy

If an engine runs below the prescribed operating temp. excess wear will occur over time. That is why fitting the correct thermostat is critical.

C300Sport

I would also note that our gauges are much more sensitive/responsive than those found in most vehicles. The majority of guages will "run up" to a certain preset point and stay there unless there is a substantial change in temperature.
Could it be that you were running through a low lying or shady area where the outside temp dropped enough drop your coolant temp a few degrees?

joshg1001

Ive been driving at night so I don think there is huge temperature fluctuations, especially not in the bay area where we stay relatively neutral in weather. Its just funny to me to see the temp needle move down because I have never seen that in any other car.

In response to the sensitive needle, it also bothers me that the gas needle moves when on a hill

Stone2486

well the gas needle moves on a hill because there is a floating level sensor in the tank.

charliele729

The temp stick needle fluctuating is normal. I drive like 5 min before I hop on the freeway going home from work. It stay ups, then once im on the freeway it drop down again to middle point, then it goes up and stays up.

phil17

Hi Guys, I decided to ask here because there's not as much users on the GLK forum. I have a 2010 and yesturday morning i got a "low coolent" warning when i first started the car. The coolent level looked fine and the car drove fine. It did not have the error on subsequent drives.

In the afternoon, the temp needle went slightly pass the 100 degree mark for a couple seconds during city driving and settles at like 97 (just below 100) afterwards. The outside temp was only around 20 degrees C. I can also hear the engine fan going very loud in the front. Is this normal? My car is only 3 months old with 4,000 kms. I booked an appointment with the dealer and but they have no time until next week to even look at the car. Thank you in advance for your time and advice.

Pete7874

Exactly. Plus, typically, when a thermostat fails, it will open up too early and will stay open, thus not allowing the engine to warm up properly. Main downside will be increased fuel consumption as the engine isn't as efficient below the proper operating temp.

Pete7874

If the temp was too high, you would probably get some kind of a warning on the dashboard. I don't think you're in an immediate danger of anything, but it is probably a good idea to have the dealer look at it and check if there are any trouble codes stored in the ECU.

phil17

Thank you Pete,

I do have an appointment booked at the dealer I purchased the car from but also e-mailed a local corporate owned dealer because its closer to home as my own dealer told me they have no time to see me till next week. The corp service advisor called and said it is normal for the GLK (i'm guessing the C350) to run at a high temp and as long as i don't get to the red mark or get anymore errors, it should be okay to drive. I've never owned a car that had a fluctuating temp needle nor an aux fan that sounds like a fighter jet but I guess i'm just new to the MB experience... Will report back if the car catches on fire, lol

Glyn M Ruck

Slight temp variation is normal. If it becomes abnormal due to a lazy thermostat (Benz thermostats fail wide open) then the car will not warm up sufficiently & will trigger a P0128. When this happens replace the thermostat.

Good Luck

phil17

Thanks guys . I really appreciate the help glad to know the car is running normal

tetobasha

I know it's old post, but just want to know what did the dealer say when he looked at your car.. Because I have the same issue, and the temp gauge fluctuate sometimes between 80 and 90. Thanks in advance.

tetobasha

I know it's old post, but just want to know what did the dealer say when he looked at your car.. Because I have the same issue, and the temp gauge fluctuate sometimes between 80 and 90. Thanks in advance.