J. Boggs
I just finished with temp problems on my 560 sel. Last month I thought I had problems with my aux fans not coming on and engine temp running about 100 - 103C with a/c on on days when it was 90-95F with a/c on on the highway. Like every one else with similar threads I thought there was an aux fan turn on problem. Then Murphy struck this month. I was out for a Sunday drive - stopped to get gas and noticed a wisp of steam from under the hood while tanking up. I started the car and - Bang - antifreeze all over the place. The dreaded broken rad neck syndrome. Patched the rad and limped home with 5 gallons of water in the back seat - adding as required. I replaced the rad and took the car for a spin - temps were about 110C with a/c on on the highway. Got home and let the engine cool. Then started it with hood up and watched the temp guage. That's when I found the book is correct. The aux fan came on ONLY when the engine temp hit 107C and ran until the temp dropped to 100C. So what I learned was that the aux fans are only for backup to keep engine temps below 107C. Why was my engine running hot with a new rad? - Murphy again! The viscous clutch was not engaging the fan - it just lazily turned as if at idle. The clutch was new 3 years ago and only had 7000 miles on it. I put a new one in - and Presto - engine temps now staying at 85C to a max of 97C under high outdoor temps on highway with a/c on. If your engine temps are under 100C - from what I have learned - don't expect to see your aux fan come on. It's a good thing I LOVE my old girl - she has cost me a lot of $$$$$ this month - and she still is beautiful! and yes - I am talking about the car - not my wife!!!:p :p :p :p