I own a 1991 E300 with a 124 030 engine. I rarely drive it but my wife insists that it reaches the temp red line very regularly. (She's a nuke engineer so I can kind of trust her on nuts and bolts stuff.)

I just had both electric fans replaced, one shot the other close. She told me that the engine hit 120C while driving today and she pulled over and let it cool off before proceeding. (Good girl!)

I did the following test this afternoon and was wondering if any of you Techs find these results, "normal".

Outside air temp. 82F with humidity +/- 75%.

Hood was up, to observe fan operation.

Engine temp at start-up 85C

AC on and set to 78F

At start-up all fans were running, electric and engine

Idle +/- 750 RPM

1 minute, temp 87C

2 minutes, temp 90C

3 minutes, temp 100C

4 minutes, temp 105C

5 minutes, temp 107C

6 minutes, temp 110C

7 minutes, temp110C

8 minutes, temp 110C

9 minutes, temp 112C

At 10 minutes the hood was closed

11 minutes, temp 110-112C

12 minutes, temp 110C
End of test

The Owner's Manual states that the engine may hit the 120C red line in traffic. Seems odd the the red line would be reached during normal driving conditions?!

Oil & coolant levels were both nominal during the above test.

Any thoughts?

Thanks, Playing it Safe