It seems like this is a popular topic lately. I would like to know what temp the other other members cars at running at. Please give us your model, temp, ambient temp and both data for traffic driving and freeway driving:
My W124 400e:

in traffic:
ambient_temp coolant_temp
65 F 85 C - 100 C

Freeway:
65 F 70 C - 80 C

Does this seem normal?

Hey neighbor!
'89 300se
65-98 F ambient runs 80C city and freeway.

'95 c280
65F ambient runs 85C approx to 90C approx. in
city and 80C on freeway.

The 300se has more open space under hood for
ventilation and does not retain the heat
so long after shut off.
The c-280 is cramped under hood and gets HOT
in there as well as retaining heat long after
shut off. This is probably one reason that the
wiring harnesses begin to deteriorate besides
poor design of insulation.

Maybe your radiator needs renewing of fluid
with less antifreeze.
Try redline waterwetter combined with less antifreeze in the mix.
Keep an eye on it! :)

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1979 300D
133K miles
1989 300SE
1995 C280

My 1984 300D runs as follows:

Outside temp 100F, engine 90C (then up to 105C at idle);

Outside temp 78F, engine 78C...

or thereabout.

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Matt
------
Grey/black '84 300D, 194K

Ditto what Zoonhollis posted' on my 83 300D 185K miles

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Keith Schuster
99 Harley Davidson Ultra Classic
97 Dodge Ram
83 300D
Heavy equipment\hydraulic mechanic 20 yrs

Hey Rabbit,
I'm just down the highway from you a bit in Santa Cruz. My '86 300e runs at about the same temps as your 400e does. If I let it idle too long parked, it starts to really heat up.


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Kyle De Priest
1986 300e
1972 BMW R75/5 (Best there is)

My question is about ambient temparature. I would have thought that regardless of the outside temp, the coolant temp should be more constant and not be as affected by the ambient. Perhaps I am way off base here. Anyone have any good scientific or simple explanation for this? Thanks everyone for answering these questions. The engineer in me just does not want to let this rest.

FYI, my friend in Hawaii has a 99' e430 and it always seems to run about 85-95C no matter what he is doing. The temp in Hawaii is always around 70-80 F.

Well, let's take a look at thermodynamics. Thermal energy will flow from hot to less hot or cold if you will. If you have two objects at the same temp sitting in close proximity, nothing will happen. If one is cooler than the other, the the hotter of the two will transfer heat to the cooler object until both are at equilibruim, so, if you have a car with a cooling system at operating temp, the heat transfer will be affected by the temp of the other part of the system, namely the ambient air. Now we all know that it's much nicer to have a fan blowing cool air in your face rather than hot air. IF the air is dry and you're sweating, the evaporation of the sweat will help cool you down. If the air is damp, we all know what that feels like. Could be they called the evaporator in A/C systems that name for that reason. At any rate, when, the air that is "cooling" your engine is almost as hot as the coolant air interface AKA radiator, very little heat transfer is going to take place. If the ambient air is cooler or cold, you will get a much imporved heat transfer. That's why we have thermostats. We all know it takes a bit longer in the winter to get things up to operating temp, when in the summer on a 100 degree day, the car is at operating temp by the time you roll down the window. Anyway, when it's hot out, the cooling system has to work a lot harder to move the heat than when it's cool. This is directly related to the ambient temp of the air passing thru the radiator and the condenser. BTW, why do you think the condenser is in front of the radiator?? 50 points for the correct answer... :D :D :D

------------------
Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE

I've got all you guys beat regarding the coolant temperature readout. This is on my 1995 S420.

On the Freeway, things look OK:
With ambient temps <80 degrees F, my readout is usually at 85 C. Above ambient temps of approx. 85 F, I'll have my A/C on, and I'll see gauge temps of 85-95 C.

In Traffic:
With ambient temps <80 degrees F, my readout is approx. 85-95 degrees C. I think I've seen readouts as high as 100 C (No A/C). Above ambient temps of 80 F, with my A/C on, I regularly see gauge temps of 95-100 C. Above ambient temps of 90 F, A/C on, my gauge readouts commonly show 110 C. This is where I think that either the coolant temp is too high, or the gauge is reading higher than the actual temperature. My auxillary fans click on at 110 C gauge. But like all late-model M-B's I've observed, the fans blast for about 15 seconds, then shut off for awhile. The fans repeat this short cycling period. My fans shut off before the temp readout drops below 110 C. I'm sure this sounds familiar to many.

Let me quote a clipping I keep in my M-B service folder. It's from Popular Mechanics magazine, "Car Care", "Service Tips", April 1996: "All M-B cars may indicate hot temperatures (up to the red zone) while under a heavy load or stuck in traffic. This is normal and no cause of concern."

I repeat this to myself when I see 110 C on my coolant temp gauge. It helps somewhat.

Mike

In two years my engine temp guage has only gone above 80, when I've done Italian tune ups (short bouts of high rev driving in lower gears). It went up a little over 90 then. Other than that longest trip I've taken was 22 hours of straight driving in temps around 80 degrees (This is Canada after all) Temp never went over 80.

JP

Very good reply macS420. I will repeat that to myself evertime the temp reading goes above 100C. no harm, no harm... yikes!

It is a little errie. And yes, my temps does go to about 95-100C when the ambient outside is 85F and above.

My car runs around 90-95 deg C in normal driving and 95-100 with the AC running. This does seem a bit high to me, although I did have my thermostat changed a while back. Prior to this, it took an 8 mile drive to get it to 80; it would warm up only to 60 degrees after a few miles. I guess I should be happy that I'm getting warmed up fully; mileage at 60 deg C was about 5 mpg worse than normal. My '77 300D held 80 deg. C constantly unless the AC was on.

------------------
Robert W. Roe
1984 300SD 173K mi

Mine constantly running any where from 85C up to 110C.....there shouldn't be anything to worry about as long as the needle doesn't hit the red zone of the guage....

Andy Kuo

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<UL TYPE=SQUARE>
<LI>1992 Mercedes-Benz 400SE
<LI>Pearl Grey/Black Leather
</UL>
ICQ#26950002
Mercedes Owners ICQ ActiveList ID#61730549
Mercedes S-Class Page
http://akry.homestead.com http://akry.homestead.com/files/mercedes_benz_2.gif

well i am always wondering about running temps, my 82 300D has been running at 100 Celcius since i bought it, and lately at about 105. i'm not sure if thats healthy tho.

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Maciej Jamrozek
Born in '82
'82 300D TurboDiesel 500+K

My R129 always at 95 with AC on regardless of the ambient temp. Occasionally it will get up to 100 or 105 when in city traffic. Whereas my ML always at 85 regardless of hte ambient temp (summer or winter has no effects on the reading). I often wonder if my R129 is running too hot. It will be great if someone can tell us what is the optimal range of operational temps are.

95 R129
98 ML320

The 300SD runs at 85C. On the rare occasions I can go faster than 70mph on the freeway, it creeps up slowly. If I try to sustain 80-85mph it creeps to 90; I haven't gone fast enough long enough to see if it keeps going up.

The E300 Diesel stay rock-steady at 85C. (I was going to say it was "Like a rock" but that's another brand and another forum... :D

None of the cars exhibit variation with outside air temperature.

------------------
'96 E300D 60k mi (wife's daily ride)
'95 Audi 90 120k mi
'92 GMC Suburban 139k mi
'85 300SD 234k mi (my daily ride)

This is insteresting. I noticed that some car's temp vary with ambient and some do not. What is suppose to be the norm? Or is there no norm. I thought it would make sense for the temp to be a little higher if you are traveling in warmer temps simply due to heat transfer properties. Thanks to the earlier post on thermodynamics. Perhaps Benzmac has some input on all this.

I read an article in The Star magazine last year where a technician addressed this subject. He said that the newer cars are built to run hotter than older models. Around 100 or so instead of 80.

------------------
Jason Priest
1986 420SEL

420SEL,
If thats the case, then how come my 98 ML runs at 85 no matter what the outside temp is? I still think there is more to it. Maybe everybody's car using different themostat, the age of the coolant? I check with my dealer and they told me the new coolant they put in cars nowadays only requires changing every 100K miles. I don't know if I want to trust them on that one either (sort of like oil change every 12K miles). Hope I am not opening another can of worm here.

95 R129
98 ML320

I wonder if there are "winter" and "summer" temperature thermostats made for MB's. Also, I'm curious about how much sample-to-sample variation there is between thermostats of the same temperature ratings.

I'm not sure if I understand their operation correctly, but don't they simply let water flow through the cooling system to the radiator when the coolant reaches a certain point?

Robert - I asked what might be your next question a while back ("Why not a thermo that opens at a lower temp") and got a pretty detailed explanation about thermal/combustion efficiencies and the thermos being correctly designed as-is. I was looking for a way to get that 20% power back when the motor gets *really* warm and sluggish.

On the topic:
93 190 2.6

Speeds above 45mph, regardless of ambient temp registers 81-82deg (even at 95mph sustained in 115deg w/ 22% humidity - high desert SoCal).

Speeds below 45mph with temps above 70 can drive to 85-100 (high end being stop and go at 95deg ambient + heat from all other cars and pavement). Really noticeable cooling event when those aux fans kick on at 102 or whatever (seems damn high to me, BTW)... At speeds below 45 with weather cooler than 70deg right about 82, may vary depending on how many lights I have to sit at but not much higher than 85.

Never less than 80, unless'n I'm warming her up.

Sustained high speeds always got to the diesel but not to this car. And I have to say that after YEARS of driving other cars I sooo appreciate a guage that actually shows the fluctuations, unlike every american POS I've ever had where you're either "cold", "right in the middle" or "overheated". Same with oil pressure guage, but that's neither here nor there...

Nice thread btw how new is new????
94 C280 runs @ 90c &gt;80 to 114 deg here in Houston.Idle in a SHORT traffic light goes to 100-110c-yikes!
Recently 80f or &lt; runs @ 80-85c. Question, do all the autos have a lower engine cover? which one allude to that may contrubute to higher temps? I rin a fan in the garage towards the grill to get the heat out, guess ever little bit helps.

85 300SD even with that ferin tune up gets only up to 80-83c in 90+f days. Now with 85 or &lt; days runs @ 77-79C. Course when I bought it I used the heavy duty flush that say to run it for 6 hours. Used it all week (as a run about)Should have seen the dark brown mud that poured out! Since then it's been really cool. Thinking of doing it to the C280 just to optimize the cleaning out of the system. My 93 F-150 had same treatment, runs very cool even in the 114f days. LH

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93 F-150 4X4 110k still strong(them oil changes pay off!)
86 Ninja 1000 60k(sold)
85 300SD 168k
94 C280 58K (what a blast to drive, 100+ easy)

Leon, what brand of radiator flush did you use? I know of the Prestone Super Flush or similar, but I'm not sure if it's safe for MB radiators.

I'm assuming that you have to drain the coolant and run it with plain water and the radiator flush? I may have to wait until spring for this; temps here are getting close to freezing at night.

Thanks,

------------------
Robert W. Roe
1984 300SD 173K mi

Hey Rabbit,
Here in columbus ohio where the temperture can differ as much as 35F in 24 hrs, i notice my 83 D-T stays at around 85C pretty much rock soild or up to 95C sometimes in heavy city traffic. But it usually falls back down to 85C or so quickly. I think my gauge is a little sticky around that aera on the gauge anyways!!!!
Brett

------------------
83 300D-T

Hi Robert:
I use the Prestone and there are two types, one a 10 minute flush and the other a Heavy Duty. This one has directins for running it in the engine for 6 hours. I seem to remember that it was ok for aluminum applications. But the best I can tell from all the posts it appears that MBs run hot. Still a bit unsetting, we had a record heat wave in Texas (Houston area). In 114f days the 94 C280 was running at 95-100 and in traffic up to 100C. I do have an idea about the lower engine shield. Will play with the idea to see if the added air flow helps. Will keep you posted in a few weeks. Night shift! :)Regards LH
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Robert W. Roe:
Leon, what brand of radiator flush did you use? I know of the Prestone Super Flush or similar, but I'm not sure if it's safe for MB radiators.

I'm assuming that you have to drain the coolant and run it with plain water and the radiator flush?

"YES that's what I did."

I may have to wait until spring for this; temps here are getting close to freezing at night.

Thanks,

<HR></BLOCKQUOTE>

In response to high temp normal for MB
 

It seems very odd to me that MB cars are supposed to have high temp .Why does my 2002 Lincoln Towncar never budge from 80
degrees in 100 degree weather, a/c blasting stuck in Holland Tunnel ? Shouldn't a MB be better ? I have a 300 E and a 560 SEL and I think they're the best cars I've ever owned but there has to be a repair issue to fix high temp on MB's. Also, how do MB's in middle eastern countries cope with "110 degree in shade" weather ???

A lot of american and asian cars use temperature switches as opposed to the Mercedes temperature gauge.

On these cars that use the switch as long as the cars are not deemed to be overheating or near overheating the needle stays at center. When overheating occurs the needle goes to the overheating portion of the scale. Something reassuring about gauges that stay in their neutral or center reading.

300SDL - about 90C + or - 2C open road; 100C + or - 5C in city traffic. ML320 - about 85-90 all the time.

1999 SLK230/auto 49k miles

Amb temp 90'f
Coolant temp: 85'c at highway speed
95'c sitting in traffic

NP

temp
 

Hi, the temp on my car is:

1996 E230 W210.

City Driving with Traffic ranges from 97-110 C BTW, I live in a hot humid asian climate.

Never went more than 110 but is normally around 98 C.


I am quite horrified by this since it is quite close to the red mark.

If this is normal for a Benz, I hope they change this design coz its making me a bit paranoid.

Strangely, my car does the opposite, that is it runs too cool, regardless of the ambient temperature(which varied between 16-34 degrees C (that's 60-93 degrees F) this spring and summer).

The small plate in the engine bay gives the normal temp as between 60 and 80 degrees Celsius.

At highway speeds, the gauge stays at 60C or a bit higher, when slowing down it raises slowly towards 80C. After 5 hours of highway driving, when entered city, it raised to 80C and even one hair above.

Never checked the water temp with a thermometer to see if the sensor reads well, just trusted the "60-80C" recommendation.

The car doesn't have (and never had) auxiliary fan, just the main belt-driven fan. Coolant was standard antifreeze(unknown brand) + water, heavily diluted by adding more distilled water. Oil is 10W40, mineral (completed once with 1 liter of 10W40 semi-synthetic).

My uncle's 300E (from 1988, with A/C and single auxiliary fan) actually runs slightly warmer, around 85C. Paradox?

~Regards,

Nautilus

Running Temp's
 

:cool:

OK Men Let's talk Heat:

1997 E300D w/ 119K on the clock

I have owned this car four months in Airizona.

Outside Air temp in April 80 F; temp gage at 80C

Outside Air Temp in July; 105 F; temp gage 85-90 C in combined highway and city driving.

If I park her with the A/C on in July she may raise to 95C and that is my story.

Great cooling system for such consistent results with very diverse air temps.

Have a Great Day!

heated discussion
 

I've just read this thread.
89 300CE runs just about 85C all the time. Creeps up a bit in traffic, but not much.
My question is: Shouldn't there be an "ideal" operating temp? For best cumbustion and fuel effeciency? If so, what is it?
When I bought this car my tech's advice was simple - Keep up with the oil changes and never, never let it overheat. It croaks head gaskets.
But I think mine should run hotter. Do thermostats come with a temp rating of some kind?

Re: heated discussion
 

It is, the "ideal" temp is that specified in the manual, or on the small plate in engine bay, above right headlamp. That is, 80C.

~Nautilus

Mine is a 85 190E 2.3 8vlv, and in normal driving conditions it will keep a steady 85C, it used to be 80C, but the new thermostate is set for 85C apparently this is better. When stuck in traffic temps will go up to 100C and that's when the fan kicks in and cools it right back down to 80C.

I didn't like how the temp would rise up and fall down all the time, knowing a bit about metals I know this causes the material to tire out, so I put a switch in the cabin to control the aux fan and whenever I get stuck in traffic I switch it on, it keeps the car at a 85C steady even if I'm sitting in traffic for hours.

xp