What is normal operating temperature range? - PeachParts Mercedes-Benz Forum

benedict · #1 09-21-2010, 04:36 AM

Hi All,

Can someone please explain to me what is the normal operating temperature range and when it is deemed to be an overheating issue.

I purchased my e300 diesel (om606, no turbo) in Winter this year and since then the car has run a little above 80 on the temp guage.

Today we had our first warmish Spring day (Sydney Australia) at about 25 C/ 77 F outside temp. I was stuck in bumper to bumper traffic climbing a slight incline for 25 minutes until the road crew cleared an accident. For most of it I was accelerating and stopping with the AC running. I was getting a little concerned when the temp guage went all the way to the mark between 80 and 120 (I think it would make it about 90) and then it went up another little bit from the 90 mark at which point I turned of the AC.The traffic cleared shortly after and then after getting some air flow happening, the temp went back to arround 80.

Does this seem like a normal operation?
Thanks

layback40 · #2 09-21-2010, 04:50 AM

Hi benedict,
To have that happen on a spring day in Sydney is a concern. I would be having a close look at the cooling system. In particular, is the fan clutch working properly? Is the radiator core clean & is the thermostat opening properly? When you get a late January hot day in that situation it would not be nice!!

shertex · #3 09-21-2010, 08:07 AM

Perfectly normal. As I understand it, the temp gauge is not an "idiot gauge" (staying at same temp as long as it's within a certain range), but a gauge which reads actual temp....which of course goes up and down depending on conditions. And, if you'll notice, your owner's manual says that the gauge will fluctuate.

bobodaclown · #4 09-21-2010, 10:51 AM

With a load and the A/C running mine will get up to 100c on a hot 95F+ day. It cools right down if the A/C is off. Hasn't gotten much above 100c. Otherwise with out the A/C on it runs about 80c.

BoiseBenz · #5 09-21-2010, 11:03 AM

One easy check is does the electric fan(s) whirrr under these conditions?

vstech · #6 09-21-2010, 11:37 AM

the middle mark is 100, so you're saying it went over 100 some. I would verify your fan clutch is working and verify the aux fans are coming on as set. but as long as it's below 120 you are ok. not a bad idea to turn off the a/c when it gets hot, but not NEEDED.

just verify all safety's are working and keep an eye on it.

JamesDean · #7 09-21-2010, 12:16 PM

I'd suspect something is up.

I know in all of my w126s it never gets above 80C. Hot day, even with AC on.
My 201 is the same way, its cooling system is all new though.

I just had to replace a radiator on my 420SEL because it was getting over 100C when it was in stopped traffic.

Check aux fan operation (both ac activated and temp activated), check clutch fan, t-stat and cooling system.

check the fans/clutch fan first. If those seem ok, try a coolant flush (you might be due for one anyway) and replace the t-stat.

mplafleur · #8 09-21-2010, 02:34 PM

Mine all run at 80* give or take a couple, with or without AC, winter or summer, city or highway.

However I've known others who run at 100* or more even after replacing almost everything in the system (radiator, thermostat, fan, fan clutch, temp switches/sensors, etc.).

speednjay · #9 09-22-2010, 02:41 PM

on mine, the temp was all over the place til i changed the fan clutch. it wasnt pulling in any air at all. its funny how everyone says thats its perfectly normal for a mb to have zero control over its cooling temps. now its glued at 80c all day long..even when its 120 degrees out. the only time it rises is when i climb a hill. even then the temp wont go past 90-95c with teh a/c on.

JamesDean · #10 09-22-2010, 02:47 PM

agree. 80c is normal op temp on pretty much all of these 126/124/123/201/107/129 chassis cars

DieselPaul · #11 09-22-2010, 02:51 PM

My car sits rock solid at 80*. 100mph with the A/C on through the mountains is what it took to hit 100*.

Oldwolf · #12 09-23-2010, 10:32 AM

Mine will run 80-85 with AC on and highway cruising. In stop and go with AC on and a hot day it will hit 90 and maybe occasionally 95. My fans all work and I have a new fan clutch and original radiator.

Actros617 · #13 09-23-2010, 12:06 PM

My 300SD runs at one notch above 80*C (not 90*C) at all times, but it goes up to 85 if I was to hill climb

mach0415 · #14 12-21-2010, 07:21 AM

I replace a defunct t-stat a week ago because I was tired of having numb feet/legs and nose on the way to work. Now, I have heat, but the gauge does not get over 60. I noticed the seam on the coolant degas bottle is cracked. i am thinking that this is the culprit, since the cooling system is really not pressurizing. What are your thoughts?

#15 12-21-2010, 07:54 AM

Quote:

Originally Posted by mach0415

I replace a defunct t-stat a week ago because I was tired of having numb feet/legs and nose on the way to work. Now, I have heat, but the gauge does not get over 60. I noticed the seam on the coolant degas bottle is cracked. i am thinking that this is the culprit, since the cooling system is really not pressurizing. What are your thoughts?

Replace the bottle, it's part of the pressure system. It should be over 80 with everything correct.