I respectfully disagree. I'm referring to the normal operating range for the coolant temperature. There's an upper and lower limit. When either is reached, action is taken to return the coolant temperature to 87 degrees C, which is the normal operating temperature, not the normal operating range.

The temperature will fluctuate within this range. This is normal. When the fluctuations are not controlled and the temperature is not returned to 87 degrees C, then there is a problem.

 

85 TO 110 DEPENDS ON TRAFFIC

 

CHECK YOUR OUTSIDE TEMP SENSOR LOCATE AT EITHER LEFT OR RIGHT OF YOUR FRONT BUMPRE ONLOWER GRILL ...IF YOU DONT SEE A SMALL NIPLE STICKING OUT THATS THE PROBLEM ...THE SENSOR POP OUT OFF THE HOLE AND DANGLING INSIDE
THE BUMPER CAUSING ERRATIC TEMP TOREGISTER IN THE INS CLUSTER

 

I gotta agree with you. There has to be a range. NO system could hold the temp absoultely steady. Even my shop manual tells you if the temp climbs in traffic, place the transmission to neutral to help reduce heat from the transmission.

 

Ever pull out the thermostat? It will have 87degrees stamped into it. NOT a range. Your car may operate within a range but 87 degrees is the target. Less indictates that too much coolant is bypassing the t-stat. More indicates that either the t-stat isn't opening fully or that the efficiency of the rest of the system has decreased to the point that a full open t-stat can not regulate at it's set temp. Either not enough air can flow through the core (bad fan clutch, debris blocking the fins etc) or not enough coolant can flow through the core (deteriorated w/p impeller, core blockage due to oil or corrosion, etc) Given a radiator core that has the proper amount of unobstructed air flow and proper coolant flow and coolant mixture, the t-stat WILL regulate at 87 degrees. After all that is what it is designed to do. Defing the operating range as up to 110 degrees is wrong. 110 is the upper safety limit not the operating range.

 

We've already established everything you just said through clarifications of your original claim, which was incomplete at best.

You should note, however, that we're talking about an automobile's cooling system. It's not as precise a system as you would have everyone believe. It's neither critical nor economical to produce a cooling system that can do as you originally claimed. Each piece of the system has it's own tolerances which are likely added together in the whole into a system that also has its own tolerances.

Your understanding of an automobile's cooling system is one big exaggeration. They are very simple. Nothing extraordinary going on here.

 

right.

parts wear out in time (radiator, water pump, fan clutch, thermostat), and that tolerance is considered.

 

Well we're gonna have to disagree here. My knowledge of mercedes cooling systems is extensive, I'm an 8 year Mercedes technician. When my customers come in with a car that doesn't regulate it's temp where it supposed to I fix it . I don't tell them that it's normal for their car to run hot. When everything is right Mercedes do not run hotter than their thermostat. Period. There are a lot of variables that affect the cooling system that can cause overheating. Specific gravity of coolant and the charge level of the a/c both can have a large impact on the cooling system. It's not just as simple as yeah it's supposed to run a little hot. Why would one of the most precisely engineered cars take such a lacksidasical approach to the cooling system? They don't. It's only when their owners take a lacksidasical approach to maintenance do they tend to read more than the proper 87 degrees C.
As far as it not being feasible to build a vehicle that performs as I describe.... My 97 900SE regulates it's temperature precisely where it's supposed to. Highway or traffic, 10 degrees or 100 degreees outside no matter, with an automatic trans and 20 PSI of boost. Never does the guage read more than the set temp of the thermostat. Surely you wouldn't argue that Saab is a better engineered car than Mercedes.

 

You keep contradicting yourself. You insist there is no range, then describe the range.

Just go ahead and keep believing what you believe. If you make your customers happy, that's what counts.

 

I'm not following you here (is anybody else) The only thing I have contradicted is your misinformation. I have simply been maintaining the assertion that your engine should not run hotter than what the thermostat is rated for. (duh!) 87C for a mercedes, no? When your car tends to run hotter than this then there is a problem in need of repair. Mercedes are so complex that sometimes that repair isn't even part of the cooling system. If the gentleman who started this thread wants his mercedes to perform correctly his fan clutch needs examinind as well as the a/c charge level and coolant spec. gravity. Therein a fault will be found and once rectified the car will run at 87C in traffic.