Read Dieselgiants thermostat replacement page and did not see suggestions for what temp rating to use, what might be best depending on climate.

My local auto parts store offers three thermostats for my Mercedes 300D (1980).
170F, 180F, 190F.

Using a conversion calculator I figured these to be 77C, 82C, 88C.

My engine came from a car originally sold in New York.
I have it in a car in hot desert part of California. Lately we are seeing 100F daily, 80F at 9am.

I want it to run cool and am wondering if I should just use the standard issue 180F t-stat (it is the most common one
sold by the store).

Curious if different states (climates) may have gotten different original thermostats.

What are you all using for thermostats ? (in your 617 Diesel Motors).

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80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

Why would you want it to run cool? Everything I've read indicates that hot (I'm talking 80-100C) is better than cool. Better mileage, less engine wear, etc. I think the engine was designed to run at 80C.

My thermo said it was 171 F but it tends to run around 90C. My gauge may not be totally accurate, either. In any event it's been over 100 F the last few days here and the car runs at the same temp. it has since I put the T-stat in.

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Ralph

1985 300D Turbo, CA model
248,650 miles and counting...

The cool I am talking about is 100C with full AC on in desert heat.
That is the way it ran when I purchased it (in 1984).

Right now I am getting 100C with no AC, and what I perceive to be about 110C
with AC on. Have not had to idle in traffic yet and am worried it may not do well.

Saw Brian Carlton suggestion to go without thermostat, but don't know if I want to try it.

With our gasloine powered hot rods in the 70's we concluded the thermostat slowed down the water so it would get cooler in the radiator before returning to the engine. Just our theory...

Still want to know what t-stats are people buying ?

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

The one I just replaced with is rated at 186ºF (85.5ºC). It's what they had in stock at Advanced Auto. My temp. was jumping badly before, and is stable now, but seems a tad on the warm side still.