1994 C280 running too hot - PeachParts Mercedes-Benz Forum

dwcasey · #1 06-10-2002, 12:26 AM

Dunno what's up. I changed the oil ((have not changed the oil filter yet, though)) using Mobil 1 tri-synthetic 10w30.

It will run above normal without the A/C, and when the A/C is turned on, zoom! up the temp goes.

I used a topsider to remove the oil. It only pulled about 7 quarts out and when I refilled it, it was just to the max mark on the dipstick, so I sucked some out...now it's about 3/4 of the way up between the min and max.

And, to top it all off, the Check Engine light has come on

Ali Al-Chalabi · #2 06-10-2002, 08:10 AM

How hot is it getting? Start by checking the aux fan fuse.

Jeff W · #3 06-10-2002, 04:22 PM

I have been hitting 100 degrees with the A/C on on hot days in stop and go traffic lately. As soon as I get out in the open it stays right at 80, or a little higher. Is this what you guys are experiencing, or is this hot? And it's a 94 C280 too.

dwcasey · #4 06-10-2002, 04:55 PM

That's close to what we're getting, but I would say we're between 80 and 100 during highway use and at or a little higher than 100 during stop and go in town type driving. This is up quite a bit. This car has yet to see 100 until the past couple of days.

We're in Northwest Arkansas and temps. have been mid 80's in our area.

blackmercedes · #5 06-10-2002, 04:57 PM

In hot weather, stuck in traffic, with cold air blasting from the vents, both our 98MY cars will run a constant 94-97C, with 100C occasionally.

Once traffic opens up, 85-89C is about the temp it falls to.

Open road in cool weather sees a constant 83C.

(BTW, I checked these temps with the PBU diagnositics mode, so that's why they are more accurate than the guess-the-gauge numbers)

dwcasey · #6 06-10-2002, 05:24 PM

What is PBU diagnostics mode?

blackmercedes · #7 06-10-2002, 05:47 PM

On my ACC panel, if I press the "rest" button for five seconds while driving, it cals up the diagnositics panel, giving the readout from many of the car's sensors.

I can check coolant temp, interior temp reading, bumper-mounted outside tep sensor, heater core temp, AC pressure, refrigerant temp, rpm, road speed, and charging voltage to name a few.

I can't remember how to call it up on your pre 1996 ACC unit, but it can be done. Check David C Klass' posts on this subject...

as well as this link:

CLK 430 Problem

dwcasey · #8 06-10-2002, 05:53 PM

Wow, handy information. Too bad it's for 1995 and newer

I might try it on the 1994 just to see what happens.