Hi I just bought a new thermostat from Mercedes, I tested it in a pot of hot water at 180f on the stove and it opens fine, but my car won't get above 60c if I'm on the highway or city. Any thoughts? Car is a 86 300 sdl

I would suspect the guage.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

The wires or the sensor?

the sensor seems most likely, have you gotten a thermometer to verify the temp is correct? HF sells them pretty cheaply.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Check the degas bottle for cracks causing the cooling system to not pressurize as well. If it is not properly pressurized, proper operating temp may not be obtained. My gauge is also suspect, as I have the same concern after a recent replacement. At times, the gauge will momentarily jump to 80 then back to 60.

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Thanks,
Mark in NC

"Spark plugs?...We don't need no stinking spark plugs!"
1985 300SD "Der Silberne Schlitten" 420,000 mi


Wish these were diesel:
2003 Ford Club Wagon 130,000 mi

Maybe a silly question but,... you couldn't have put in backwards? My TD was running cold when I got it, come to find out, someone had installed the T stat backwards

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

I put the t stat towards the engine, like it went inside the engine more then the radiator hose. Is this the right?

Also could my radiator cap be bad?

What is hf?

It should go this way:

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Yes that is the way I put it in

Harbor Freight. Good source for inexpensive tools.

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Joe

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1980 300SD - 495k miles - 'The Ambassador'
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Former Family Members
95 C280
73 280SEL
90 300D
87 300SDL (X2)
86 560SEL
84 300D
80 300SD

my 190e temp gauge would work fine from 0-80 but above 80 it would jump up to 120, freaked me out the first time. you should be able to test the gauge with a variable resistor.

What is the ambient temp? diesels don't produce as much heat as gassers, that's why you'll see truckers covering part of the radiator.

Try driving up a long steep hill (if one is available) and see if the temp rises.

does the heater put out hot air? or luke warm?

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Remember the golden rule, you get what you pay for.

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Do you have all of your noise encapsulation panels on? On my 86 300sdl my temp always ran just below the 80 line. I finally found my big encapsulation panel for it and installed it last month and lo and behold my temp gauge now sits right in the middle. The only panels I had were the side panels prior to this, but now I have the panel under the engine and under the transmission.

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John
1986 300sdl
1985 380se