heat gauge
 

Hello. Today, I just had the water pump replaced in my '92 MB 300E 2.6 (173K miles), and now the heat gauge is consistently over 80 (looks like around 85 or 90). The red area is, of course, at 120.

Before the water pump, it always ran right at 80, except when I would run the air conditioning, and then it was around 85 or 90 when I'm at a traffic light or otherwise stopped for a long time.

The last time the water pump was replaced was exactly six years ago. Should I be concerned about this? Thanks for all replies!

Joy

Looks like they also changed the thermostat and brought it back up to normal operating temp. Running right at 80C is not normal, that is a problem. Running at least 85-90C and higher is what it is supposed to do.

thank you!
 

Thank you for such a quick reply! I was beginning to worry ... funny, I always thought running at 80 was normal. You've calmed my nerves ... :)

Hmmm.. I think that 90*C is acceptable from what I have heard, but I do not like to see my temperature above 80*C, which it does occasionally do when it is above 60*F outside and I am in stop-go traffic, then it goes to about 85*-90*C. I have not owned the car that long, (about a month) and it has only been in the 40s-60s, so I am hoping that when the temperatures soar into the upper 80s and mid 90s this summer that it will not be anymore of a concern for my car. Meaning, I hope that 85*C is the highest it will go. When I am on the highway/freeway, it will drop below 80*C.

I am soon placing MB/Zerex coolant in place of the green coolant, so hopefully that will help as well.

I understand what you are saying however- you are wondering why it is reading higher now that before. I wish I knew. I am sure someone here will have more info regarding this.

Good luck.

Oh, I typed the above before the reply before was posted. I suppose I was typing the same time the other was.... well that is good to know that my car is operating at normal temperatures as well.

The thermostat on the car is an 87C thermostat. That means, according to specs, that it starts to open at 87C. It will not be fully open until 102C is reached.

The reason that the car was running at 80C is that as the thermostat gets older, it gradually starts to open earlier and earlier. I replace my thermostat almost every time I change the coolant. When new, it always runs at 90C and up. Byt the time it gets to be about 3 years old, the engine starts running a hair below 85C if it is winter on the highway.