Normal Operating Temp of 300D - Page 2 - PeachParts Mercedes-Benz Forum

gsxr · #16 12-01-2003, 12:07 PM

Quote:

Originally posted by Orkrist
My cars thermostat is stuck open! Once it finally warms, its usually around 80; 83, 95, 78, etc. I am, on the other hand, freezing... It all get fixed in 01/04.

If the car is staying above ~80C (or close to it), the t-stat is probably fine. Much more likely that you have a problem with the ACC system, specifically the monovalve. Anything over 60C on the gauge (assuming the gauge is accurate) will give you decent heat. Your pushbutton unit is also suspect, at 20 years old they really start to get flaky. I just had to replace that in my '84, along with the defrost flap & center vent vacuum actuators. I did the monovalve back when I bought the car (the diaphragm was torn - yours probably is too, if original). The system works *much* better now.

gsxr · #17 12-01-2003, 12:11 PM

Quote:

Originally posted by jfikentscher
In the summer mine ('87) runs just over the 80 mark, but in the winter it usually does not get over the 60 mark. I must need a new thermostat. Probably it is stuck in the opem position.

Joe

Joe, yep, that sounds a lot like a stuck (or at least defective) t-stat. ONLY use an OE or OEM t-stat (Wahler or Behr). It's a lot easier to replace if you pull the rubber intake snorkel out of the way (one clamp on each end holds it), and also the round sensor directly in front of the t-stat housing (this makes it 10x easier to R&R the t-stat, which only fits ONE way or you'll break the housing.) You'll want to do this ASAP, as running the car at 60C is causing excessive engine wear and reducing MPG. While you're at it, disable the EGR and ARV (search this forum for details on that).

HTH,

redbaronph123 · #18 12-01-2003, 09:37 PM

Quote:

Originally posted by Gurkha
This is the first time I am hearing this, as far as I can tell if I were to block the radiator which I have tried as a test of my Nisaan, the temperature goes up accordingly and even on test benches, both MB and Nissan temp gauges exhibit the same specs, in a tub of hot liquid, the temp reading is same for both the MB as well as the Nissan. Why would the Japanese joepardize their engine with a thing like this.

The fact of the matter is that unlike MB and other Euro cars which are specificaly designed to run in cooler Euro weather, Japanaese cars have much superior cooling systems and in general tend to run much cooler. I have taken both the vehicles as well as my friend's G-Wagen with OM 617 turbo engine to the desert in Rajasthan and can tell you that between the three, only the Nissan help up its poise at 56c ambient outside temp. Gotta give the Devil its earned due in this case.

i've had quite a number of jap cars.. and based on my observation (no factual evidence to really commit on this)... whether its a cool day or a very hot day... my temps in the Honda Accord, City (asian car) and our van stays in the middle.... never goes up or goes down too cold. And when it does to hover around the 3/4 of the temp gauge... then that is the time we worry about the cooling system. And true enough, when the temp moves... there is a problem. A leak, a plugged hole or whatever. Unlike in MBs, whether your cooling system is working great or not, the temp moves up or down depending on the 'actual' temp of the car. On hot days my wagon gets around 90*C, on regular days, it gets aroudn 82*C.. and if i travel at night at high speeds and it sometimes goes below the 80*C mark, but mostly hovers around the 80*C mark. Beats me!.. ehehehe...

rwthomas1 · #19 12-01-2003, 11:03 PM

My 84 300D runs at a needle-width below the 100*C mark, always, rain, shine, winter, summer at any speed above idle. Flushed the system, tried two different T-stats, even have a 180*C T-stat in it now, etc. no change! Always in the same spot. Concluded the factory gauge is not a precision instrument and more of a guide. Also run a 7psi cap to reduce cooling system stress. No issues. I guess she's healthy.... RT