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Normal operating temperatures

Started by chazchuzzlewitt, 18 June 2006, 08:00 AM

chazchuzzlewitt

Hello, just wandered what member's cars normally run at- I remember reading somwhere that Mercedes V8's often run pretty warm- my 350 sits at around 80-85deg around town and up to about 70mph, then 90deg or a tad over at 80mph plus- does this sound normal?

davestlouis

I haven't gone 80Mph in years...too many "boys in blue" patrolling around here.  My cars do the opposite, they get a little warm in slow traffic and the needle drops to just over the 80 mark at speed.

Tomi

The original thermostat on a M117 is 79 C and my engine never goes over the 80 C line

chazchuzzlewitt

hmm, yea I thought it was a little odd it got hotter at speed...

Denis

Mine never goes above 80 deg.

Denis

Paris, France

michaeld

Tomi,
I thought the thermostat was 75C.  I was just setting out to buy one too to try and solve my "Hot Blooded Aint Always a Good Thing" problem.

Is it actually 79?  I'd sure like to KNOW what my temp is supposed to be before I buy a thermostat!  On the internet, there are ALL kinds of different thermostats opening at different temps that are listed as 'OEM.'

Homer Simpson put it well when he said, "Lord, I'm just not that bright."


michaeld

Styria, Tomi, and all posterity,

Now I am starting to fear that I have unwittingly entered a "Twilight Zone" episode.  After my last post above, I (again) looked online at two MBz parts sites (www.germanstar.net/116c.htm and http://www.drivewire.com/mercedesparts/catalog/mercedes450selthermostat.html): what I found was 75C for 4.5 450SELs, 79C for 6.9s.  I then called a MBz dealership parts dept; they too show 75C as the correct thermostat temp for a 450SEL.

Where are you guys getting your data, so I can resolve this "discrepency in the sources of authority"?

I am currently believing that there is - in Sen. Hillary Clinton's words - "a vast, right wing conspiracy..." soley intended to freak me out.

Is wanting the correct part too much to ask for in this confusing day and age?

PS W/ every other car I've ever had, thermostat temp ranges was mainly acedemic; you went to the local parts store, asked for a thermostat for your particular model, and they gave you one.  Why are there so many temp ranges for MBz, and so much controversy over the correct OEM range?

michaeld

chazchuzzlewitt,
Someone should answer your problem - not just your question.  I had a similar problem when I first got my 450SEL.  I wasn't overheating, but I ran 20-30 degrees hotter than I should have.  I had a clogged radiator, 40% blocked.  Flushing won't fix it; rodding is a temporary fix.  Get a recore.  Mine was $330 w/ shop labor and came w/ a 3 yr warranty.

I bought a non contact infrared thermometer from harborfreight.com.  Just point it at the rad and take readings.  If your radiator is blocked, some places on the rad will be cooler than others.

Tomi

Sorry, 75 C it is, I should have remembered but didnt.
part A1162000015.

Mforcer

I am willing to put forward a theory on why there may be two or more temp ranges for our cars depending on where they are; warmer climates may have had a higher thermostat to raise the point at which the cooling system kicked into high gear, reducing the power sapping that would result. They could have done this if they discovered that the higher operating temp had no adverse affect on the engine.
Michael
1977 450SE [Brilliant Red]
2006 B200

s class

If your temp is rising at higher speeds, it means that your cooling system has impaired performance.  Check the thermometer first as its simple - thermostats seem to deteriorate over time and become "slower" in their response.  Check your radiator core as others have mentioned, then check your visco fan coupling.  If your coupling is worn, it will allow too much slippage at high rpm and hence insufficient fan speed.  BTW - you can't really judge the condition of your fan coupling by feeling its stiffness when the engine is not running - it can be very misleading. 

If all else fails, consider the condition of the cooling passages in your engine - if the car has been neglected there may be a lot of scaling, or the the water pump impeller may be somewhat corroded away. 

Good luck. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

Papalangi

I was tinkering with my US spec 450SEL today and got the aux fan working.

The switch that turns it on is rated at 212F (100C), it will also turn on if the AC drier reaches 144F (62C).

The US gauge has the number 175F (79C) which is where my temp stays most of the time.  The next mark up is not numbered and the top is marked 250F (121C).  I measured the temp at the top hose by shoving a thermocouple under the end of the hose.  When it reached 202F (94C), the fan came on and the gauge was dead on the un-numbered mark.

212-32*5/9=100

Michael
'83 300SD, I'm back!  It's the son's new car (12/2020)
1976 450SEL, 116.033  Sold it to buy a '97 Crown Vic.  Made sense at the time.
1971 250C, 114.023
1976 280C
1970 250/8