Where does your M103 engine temperature run at?
 

I am just curious.

My 260E almost never gets over 80....while my 300TE consistently is at 100-110.

What could be the cause of the difference? Does the 3L run significantly hotter than the 2.6L?

My wagon has had the cooling system properly flushed recently and a brand new thermostat.

Any thoughts?

My 300E 3 liter M103 runs at 82C rock solid most of the time, it goes up a bit if sitting on a hot day with the A/C on, but then the fan clutch engages and brings it back down quickly when accelerating. I've never seen it go over 88-90C....and thats only when sitting....when driving it is never above 85C even with the A/C on on a hot day....

Even if your system is flushed and has a new T-stat.....if the radiator is old it might be plugged up with dirt and not getting good air flow. And does the fan clutch engage? If the engine is getting to 90C it should be quite a noticeable roar when rev'd over 2000rpm.....if not then you might need a new fan clutch.

Well the fan clutch does roar at like 105C, but then slows down after about a minute.

The radiator is about 3 years old. Replaced it when I bought the car. I do admit it wasn't OEM.... Not sure if that would realistically make the difference though?

M103s also have two different thermostats available.

79° and 87°

Even so.....it shouldn't be reaching 90-100C with even an 87C T-stat.

Why the two offerings? Is one better than the other?

My car was only running at around 65C when I got it so I replaced the T-stat and now it runs around 80-82 in normal driving.....

Southern Hemisphere. W124 260e

Thermostat is 87 degree variety.

When running over 30Kph (20mph) temperature sits at 87 degrees even on hot days

On normal outside temperature days, sitting in traffic the temp will rise to around 95 degrees when the fan clutch seems to come in and the temp will stay there.

If the outside temperature is over 110 degreesF, with a/c in operation, idling in traffic temp will go to 105 degrees - low aux fan cuts in (caused by A/C) or I operate my manual overide switch ( low aux fans) to keep the temp down to 95 degrees.

Drive down here and it'll run that hot.

Thermos begin to open at the designated temperature, they're not fully open then.

I had the 87, my fan clutch ALWAYS seemed on when it was even remotely warm out, makes a slow car even worse. Put in the 79, I much prefer it... I still have clean oil and reach plenty hot temps.

I have new water pump, Xerex coolant, new Behr rad, etc. No issues w/ my cooling system.

We can get some 90-100F days here in the summer....I'll take ours for a spin with the A/C to see how high it gets on one of those days....

When I drove my diesel in florida a couple years ago it was super hot out and it never went much over 85C....maybe its a diesel thing.

Ivan

Many guys that are in those extreme climates use the low fan sensor on the drier to trigger a simple relay to feed back to the R15 ,which gets you High fan vs. low when the a/c calls for Low aux fan...makes for better a/c output @ High thermal Load/Ambients and will also work with the cabin sw. over-ride.

Yeah my Diesels never get super hot either. :shrug:

my 90 300se runs at 82 with rare exception, hot days with A/C on in traffic it might hit 85-87.....

MY 86
 

Runs about 82-85 unless I'm idling with AC in hot weather then it is closer to 100 but not over 100.

John in San Antonio

My M103-12V twin turbo runs 85-90 with the aux fans turning on at 92 by means of a resistor modification.

So the consensus is my 300TE runs hotter than it realistically should.

How can I figure out "why?" Is there a long term consequence to it running 10-20C hotter?

Does it have the original radiator? It might be plugged up and not getting good enough air flow.....I had that problem on my diesel. My temps dropped 10-15C under hot-day-load driving by simply installing a new radiator....it wasn't internally plugged, but the fins were filthy and blocking air flow.