Just completed a 750 mile run in the 280. Car ran good and the cooling system worked good, except...

Running through the desert at 80+ MPH A/C on, the temp would climb a little, nothing to worry about maybe 200F. What bothered me was when climbing a grade, such as the Baker Grade on I-15N, the temp almost got into the red (happened on all grades, not just the Baker Grade). Slowing to 65-70 MPH allowed the temp to drop to normal. Also, on the down grades temp would drop back down to ~180F.

Now I know the system will heat up when working, such as climbing grades in the desert heat, but it seemed to get a bit too hot. Could 50/50 mix (with a bottle of Water Wetter) be a little too thick for desert/semi-desert operation? I'm thinking of siphoning off about 3/4 gallon of coolant and topping off with water. What do you think?

On the plus side, I pulled a steady 15.6 MPG on the highway and 13.8 in the city while in Las Vegas.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.