I would like to know what the normal running temperature of the 450sl should be. I live in Los Angeles and even though it has been warm here, the car seems to be running hot. It seems to operate on the freeways at around 100 degrees on the temperture gauge and even warmer in the city. I flushed the system and added new coolant with very little result. The air coming in through the ventilation is also very warm. Also the secondary fan comes on at a high temperature. Is this normal? Should it come on sooner with the air conditioning on. Not that I've been using the air. I want to keep the engine cooler. Just a point of curiosity.
Thank you.

With the air on, the aux fan should come on in the low setting.

The car can run as high as 110 with no harm done.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I have a '76 SLC, also live in La-La land, and have done the following to keep her cool.

Had the radiator cored - not just flushed.
Used RedLine Water Wetter.
Had the engine steamed cleaned - twice !!

Bought the car 2 years ago and did a full-on tune-up myself (vaccum lines, plugs, filters, timing, etc etc) so I know its done right. Damn thing, with 130K sure runs nice.

I also use Premium only.

Anyways, my temp has come close but not past 200 degrees (your car reads in centigrade) and only runs hot (190 degrees) at 80 MPH and full A/C on the highway.

As far as your ventilator blues (old blues song - see Exile on Main St.), check the plastic cover over your blower box for cracks and replace if necessary and you may want to have the heater valve replaced for kicks. Mine was leaking a little, both externally and internally.

Cheers...

Steve Guilford
107 024 12 011890