Is 100 c too hot, 300SD
 

In the summer my 85 300SD is running right on or a little below 100 c. At what temp. will these cars steam at? Some people say its fine to run at this temp. some say not should I be concerned?

According to the owner's manual, steam will happen at about 125C if everything is in working order. Mine runs 100C when warmed up at pretty much all times. I've been running it in this condition for about 30,000 miles.

100 c is what both of ours run since we replaced (and re-replaced) the thermostats. It's been over a year, and they both seem to be happy and well-adjusted to their new temp. Should be fine.

I run a cooler thermostat my temps stay a 80c

If your coolant ratio is correct there shouldn't be a problem running 100C but I would take out your thermostat and test for when it opens in a pot of water on the stove. It should say on the thermostat what temperature it is supposed to open at. My 190 was running at 101C almost constantly so I flushed the coolant and checked the thermostat and sure enough, it was opening at 96C instead of 85C. I got a new one from my mechanic then installed it and have been running around 90C ever since.

I agree, both my cars (87 300TD w/OM603 and 98 E300DT w/OM606) both reach operating temperature at 80 c and pretty much hold there. I have occasional brief excursions to 90-95 depending on load and ambient.

100°C would be what I would expect to see climbing a hill at 60% to 70% throttle opening with the A/C on.

This is an acceptable temperature under these conditions.

My Dad's W126 runs 175°F to 182°F on the highway at cruise and only sees 212°F (100°C) under heavy loads and then the temps drop right back down when he lets up on the throttle.

He is running the stock MBZ plastic/Aluminum radiator, FWIW...

No issue as far as I am concerned on an all cast iron engine. It may be even superior to running at eighty degrees. Also the temperature reading circuit may be a little off calibration probably as is as old as the car.

Basically if you never boil over I would leave it alone.

Just something I have noticed over the years, people seem to pin point all the problems of higher temperature to either the water pump or thermostat..... While people always over look the simpler things....the radiator cap and fan clutch.....the springs on radiator caps wear out and the seal cracks.....the fan clutch throws its oil and doesn't lock up at the right temperature.....

Finally I also believe that if your running the original radiator, people should consider replacing it after 30 years....specially now that most are become NLA.....we forget that there is a transmission cooler at the bottom of the radiator....all the sediment falls to the bottom of the radiator, thus its harder to cool the transmission thus over heating and causing temperature raise....and if the transmission cooler leaks, then it can kill the transmission.....just a few observations...

Good points, when it comes to cooling, airflow, airflow, airflow, airflow....

I cannot force my ratty old W116 over 180°F (with 71°C thermostat) even going up the grapevine, in 100°F ambient temps at 75% throttle with the A/C on, so I don't know how I could work the motor any harder than that....

To the OP:

Confirm what your gauge is telling you, then report back to the forum....Robert

One more point that people also forget about, is to flush out your heater core....when ever someone does a coolant change, they never open the mono valve and drain out what's in there...on the newer Mercedes there is also a screen on the mono valve that gets clogged.

Granted I have the evil servo unit, but my cars coolant was very clean and bright....then I removed the heater hoses, I literally had the hose hooked up for a half n hour before clean water started following.

http://oi40.tinypic.com/34gswok.jpg

This I also believe can contaminant your coolant and cause temperature rise.

And also remember a good tip, if you start seeing a temperature raise....turn the heater on!

Very good points!!!!!

No you should not,given that you dont see 110C under load.
cast iron is very tolerable but if your coolant is weak (old,dirty or bad % mixture)
it can boil.

if its steady 100C I would try to burp cooling system to be sure and leave it alone....


.

I think there is some variation in thermostats, and many of them will put the car's operating temperature around 100 C. To the folks with cooler running cars, what kind of mpg are you getting? I get about 24-26 flogging it hard, and up to 30 if I'm easy on it.

I ask because I used to have an old Lincoln in which I ran 'stats from 160 to 180 F, and I lost a couple mpg with the cooler one. I also lost hot heat in the coldest part of winter, which is what prompted me to switch back to the hotter one.

Just something I have noticed over the years, people seem to pin point all the problems of higher temperature to either the water pump or thermostat..... While people always over look the simpler things....the radiator cap and fan clutch.....the springs on radiator caps wear out and the seal cracks.....the fan clutch throws its oil and doesn't lock up at the right temperature.....


Can't let this one go. The radiator cap has nothing to do with coolant temp. it only increases the boiling point of the coolant.