Is my 500SEL too hot?

[DaimlerChrysler]

I have a 1993 500SEL with 148K on the clock. Rides and runs like a dream...BUT, with highway driving w/o the AC on the temp gauge stays right at 90C. Turn the air on and it heads to right below 100C. Pull off onto regular roads and it runs right at about 100 to 105. The temp around here has been about 90ish this week. What I want to know is, is this normal. Aux fans run.

[Ali Al-Chalabi]

Sounds normal.

[DaimlerChrysler]

Thanks!

[Mike Murrell]

100C on the highway with A/C on is not normal.

Mine runs about 85C on the highway with A/C on in a hot climate.

100C might not be too scary in stop-n-go traffic.

I would suspect that it might be time to consider having your radiator rodded out or replaced.

[DaimlerChrysler]

Thanks Mike!

[Hatterasguy]

W140's just run warmer. My friends S600 hits 110C in traffic. Their is a temp switch that triggers the fans to come one. I know their is a different switch out there that will trigger them to come on at a lower temp.

You also need to keep your cooling system in very good shape. The coolant should be done every 2 years. You also should take your radiator out and clean the crap out of it.

[Mike Murrell]

He mentioned 100C on the open road. I would be concerned about any car that ran that hot on the highway with the exception of some exotic high performance ride.

100C-105C in stop-n-go...ok, but not on the open road.

[Hatterasguy]

True but according to MB as long as it stays out of the red you are fine. I don't put to much stock in that. If it was my car and the radiator was original I would replace it. Along with the hoses T stat, cap, and maybe the water pump. Then I would flush the system and refill with MB coolant.