Having an issue with my 1995 C280 overheating. Typically runs in the range of 80-90C and recently, although the weather has not been above 80F, the car has been moving towards 105-110, up to 115C when its idling in traffic, or even parked with the air conditioning on. Took it to the dealer and they replaced the fan as well as the thermostat.. and the problem continues to exist. Can someone help diagnose what this might be?

if your system is full of water[coolant]if your fan clutch is good and if your aux fans are working the problem is shrunken aluminum tubes in radiator.it needs replacing. david poole e.p. dallas tx.

If everything else checks out OK, you may just need a new radiator. I once had a car that, despite good H2O pump, hoses, correct coolant mixture, etc. it always ran a little hot. It used to be very stressful watching the temp needle in stop-and-go traffic with the A/C on as the car was always on the verge of overheating. At one point the radiator sprung a leak and I had to replace it. From that point on, the car always ran on the cool side, even on a 90 degree day with A/C on high, parked and idling for an hour.

Before discarding the old radiator, I took a good look at it. The fins were loaded with bugs, though not too bad. There was some corrosion, but with the exception of the area that leaked, again it looked pretty good. Inside there was lots of grit, probably from the PO not flushing coolant as often as needed (if ever). I'm guessing all of the above just combined to reduce thermal efficiency significantly enough. Bugs cut down airflow, corrosion and grit inside might have cut down H2O flow through a few of the tubes, at least enough to make a difference.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

First check is aux fans.
Pull connector off blue sensor at thermo housing and see if fan comes on to High speed.. if not, check fuse on top of High Fan relay behind fuse box.
If it does come on , then check resistance of aux fan sensor.
Low fan is checked by jumping high pressure switch at reciever/drier ..if low fan does not come on when sw. is jumpered , check fuse on top of Low Fan relay.. if blown, replace 15 A with 25, as this is a Benz up-grade.
If it does come on w/jumper, then the high pressure sw is not working or the a/c system does not have enough refrigerant to get high side to cut-in pressure spec for fan .
Report findings.

I picked up the car for the fourth time from Mercedes service after they took it to have the radiator cleaned, replaced the radiator cap (and had done the fan clutch as well as the themostat).. they tell me the aux fan is working. 10 minutes after leaving as I am sitting in traffic the car goes back to 110C. I was in disbelief.. I even called the radiator shop that Mercedes took the car to- he verified they cleaned the system and there was no build-up on the radiator afterwards- did not recommend replacing as they could see no blockage. The car is back at Mercedes as the service manager wanted to have "another look at it".. I see no point as they can't seem to fix it but curious as to how to get this taken care of. Any ideas?

Have them look for signs of head gasket failure. It was common on the M104 and will cause the overheating you mention.

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'96 C280 (gone)
'97 C36
'05 C230k

My gauge is always on 80 or 81 no matter what I do. When I turn on the A/C it slowly creeps up to 85. I get nervous so I turn it of and the temp drops back to 80. Would a coolant flush help? I am going in for an Oil Change today at Grease Monkey and they do these. Will Grease Monkey be able to check my transmission level since it is not like other cars when checking tranny fluid?

How will I know when I need my breaks checked?

Dumb questions but I am a female and I just bought this car a year ago and drive it maybe 4 times a week for 10 miles. I put synthetic oil in when I bought the car for 2,000 with 164.000 miles.

Sounds normal to me. If the temp goes over 95 then there is something wrong. I would have the breaks checked ASAP just so you know the condition. I am not sure if your model has wear indicators or not. All of mine do. If your car does have the wear sensors and there is no idiot light on then dont worry until the light comes on.

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I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k

If you have a Heater / AC control that is the size of the radio with a display in the middle, the procedure below will work. If you have 3 knobs it won't.

While the car is running, press and hold the REST button until the display starts to flash 01 and some other number. Press the + button on the fan speed until you see 05 or 06 ( can;t remember ) This is the coolant temp in degrees F. 197 is what my 97 C280 and 97 SL320 will see on a hot day with AC on. To clear the data function either turn the car off or press and hold rest again.

80 C is 176 F and kind of cold.
85 C is 185 F is about right on an average day
91 C is 197 F

A coolant change is a good preventative measure as would be a thermostat. With the age and miles, it is reaching the end of reliability.

You really need to find a trusted non chain store shop and have them care for the car. Chain stores are usually only interested in taking high profit margin quick turn over easy work. ( Brakes, tires , wiper blades, battery, hoses )