I believe this is mostly due to the fact our Mercedes have actual working temperature gauges that, when all is working properly, give quite accurate readings of engine/coolant temperature; whereas just about any newer car you'll drive has nothing more than an idiot light with a needle. I'm glad Mercedes installed a working gauge rather than a dummy, I like to know that my car is running at a given temp under given cirumstances.

Actually, the OP would be better with an idiot light, unfortunately. When that gauge swings up to 110°C., he behaves like a scared rabbit. The engine is fine..........the coolant is fine.............HE is not.

I think this thread should help ease his fears a bit. Your point about cooling system capacities and the thermostat's function is a good one. I have always noticed my 606 can swing between 85c-100c quite easily if it's hot out and the AC is running, but it doesn't seem to surpass 100c no matter what I do or what the ambient temps are. It just goes to show how well Mercedes did infact engineer our cooling systems and engines. 100c is an efficient and safe temp and you really have to try hard to get most of these rigs to exceed 100-110c once that thermostat is fully open. It just tends to freak people out when they see that gauge actually move, rather than sit "harmlessly" in the middle of the temp range as it does on most cars.

First of all thanks for all the input......

Bottom line though... I agree running at 105 C to 110C or 230F may not kill the motor if incidental and gets to cool off say on a down hill run afterward. However clearly the system is taxed if it is continuously running above 100C – 105C, and sure is not the way it should be running all day. Add some extra hills and yes I’m getting concerned (Please drop the idiot inferences suggesting we play ostrich lol).

See.. my goal in these hot environments is to have the motor running in a manner that when I hit a good grade I have the capacity start well below 100C & to run upwards or over 100C….not start there!

Mercedes did install “Tropical Climate” set ups for other markets needing it to keep these jobs running in the 80C to 95C range…yes even with the AC on. Apparently not in the US Market 603 years.

So in summary what I am searching for is a way to keep the motor cooler during these scorching months here in the South West Desert (as in other regions) where hot and dry is really hot and clearly not incidental (Yea I too have read the “bulletins” that say its ok to run it almost to the Red Zone but not in my car I don’t)

Anyway I have to agree with Hunter here and work to get these temps down by helping the cooling system out with steps like taking the trans cooling function out of the circuit and handling it differently, etc. And that it is important to remember that at high mileage there is more friction / heat being generated by older parts (even rebuilt).

Spoke with the folks at the MB Classic Center in Irvine today who agreed & shared several ideas and suggested I swing by tomorrow. I’ll share their thoughts with y’all asap.

Thanks...Rob

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1986 300SDL 440,xxx

That solution might be a good one for you. I am not aware of anyone else trying it for this vehicle and would be very curious as to what you determine if you implement it.

Please bookmark this thread and return to it if you to make that modification.