I have been noticing the temp gauge climbing higher than usual recently around town and especially on long inclines.The car also has that overheating smell,I'm a little worried.Any ideas?Had a new thermostat put in 18 monhts ago.

you need to provide the temp its reading on the gauge, and the ambient temp helps determine if its too hot or not.
The normal temp range is around 80 - 85 in town, a little higher if ambient is high (over 90 F) and its normal to see it climb on inclines to close to 100 but not much over that unless severe conditions
How long since the radiator was flushed or replaced?

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

What is the temperature gauge reading (at what ambient temperature)?

Blow out the fins with a pressure washer. Over the years dirt and road grime will build up inside the core and block airflow.

Its pushing over the 3rd line on the gauge which I suspect is 100 C and around town its over 80 always...I live in SF so weather is mild

Low on coolant? Dirty radiator. plugged radiator? Failing fan clutch? Worn out water pump?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Coolant is fine,radiator seems clean,How can I test the fan and water pump?

Operating over 80 is normal (you should have a 80C thermostat), but it should only approach 100 under extreme conditions.

One test you can do is for the fan clutch. When the engine is hot, use a rolled up newspaper and try to stop the fan from rotating. If you are able to stop the fan, the thermostatic clutch should be replaced. You should be able to stop it with a cold engine.

The radiator is not clean.

The radiator must be removed from the vehicle and some time must be spent to thorougly get the crap out from between the fins. I like to use a chemical cleaner (condenser cleaner). Others have been successful with a pressure washer, but, I'd be very careful with one of them to prevent rounding the outside face of the fins.

Hold the radiator up to the sun...........peer through the fins...........see anything??

I would be more concerned with the inside of the tubes, you know that calcification that really plugs old radiators up. A chem clean is always recommended on old rads with an unknown history. I've seen a lot of crud come out of old radiators when you flush them.

Of course most Behrs crack at either the hose neck or the small barb where the overflow tank attaches, if they make it to the point they are in need of rodding you just replace them

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Mine was doing the same thing. One day it shot up to the top of the scale for a few seconds then droped back between 80 and 100. I replaced the thermostat and it stays a little below the mid way point of 80 and 100.I also put all new Zerex G-05 coolant and hoses at the same time.

I had the exact same problem when I first got my 300d. Going up the mountains, the temp would climb, but never over 100.

When I flushed the old stuff, Ol' Turbo went back to normal operating tempuratures.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

You have been offered good sound advice concerning the radiator and fan clutch. I just hope my problem is the same as yours.

My problem was an A/C compressor about to go bad. After a week of your symptoms, it locked up.

A burning rubber smell from the belt will be your next symptom if it is the A/C compressor.

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1983 300SD "Guderian"
1987 MR2
2015 Camry
2015 Chevy Spark
2006 Hyundai Tucson

Yes, my compressor was recently replaced after a slow, horrible death. My fuel efficiency went way up with the new compressor.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!