I block my radiator almost completely in the winter and the coolant temp gauge sits just below 100 C. Is that well within the safe limit and how much higher can it go? Per the OM "During severe operating conditions and stop and go city traffic the coolant temp must not rise above the red marking". The red mark is 125 C or 257 F. What is the optimal temperature to run the Mercedes diesels with cast iron heads for best longevity? Economy?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

You know...........the designers at M/B did equip your engine with a thermostat.........

I don't think that blocking the radiator is necessary until it gets so cold that you have starting problems with diesel engines. So it really is a moot point. As Brian says, the thermostat should keep the engine at the correct temp regardless of the weather.

The only time I ever had to block my radiator (and that on a gasser, a '65 Olds F-85) was when I was driving across Nevada during the winter of 1990 – it was -30F all day.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

The 'stat on my '98 is shot and it runs at 65C most of the time so I temporarily installed the "Kentucky" version until I can buy a new one...

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

These engines are designed to run at an average temp of 80C with the proper thermostat. My car runs at 100C here in the desert with the AC on full blast in summer in temps of 115*F in the shade, so yes I think it is a bit hot, but not damagingly so, just uneccessary. We only used to do this in Alaska where coolant would thicken in really cold temps. Holes about 2 inches around were cut into canvass shields placed in front of the radiator and spaced about 6 inches apart, but keep in mind this was in temps of 25*F BELOW ZERO or colder! Your thermostate should do an adequate job of regulating the engine temp in your area.

Yeah I don't think cardboard is necessary at all...if the thermostat is working correctly it should run at 80C even if its -10F out....mine does...

MB's are well engineered, they take care of themselves in various environments. No cardboard required.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I've run my wagon this winter with a piece of cardboard. It works pretty well, it seems to get up to temp faster and stay there. The advantage of a radiator "jacket" is to keep all the coolant in the system at a similar temp. So instead of the block being around 80 and radiator -10, it keeps it closer to the same temp overall, not a big jump in cold weather. Just take a look at trucks, most of them have some type of radiator "jacket".

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-Randy Wakefield

1969 220D 4 speed (parts car)
1976 280C
1976 280S
1981 240D 4 speed (parts car)
1982 300D
1983 300TD (Ivory)
1983 300TD (gold)
1985 300TD (gray)
1987 190D 2.5
1970 280SEL (sold)
1977 240D 4 speed (sold)
1974 280 (rusted to death)
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1927 Chevy 4 door sedan
1938 Chevy 2 door sedan
1950 Willys Jeepster
1955 Studebaker President 4 door
1977 Ford F250
1979 Glastron 17'
1948 John Deere A
1960 John Deere 2010
1979 Satoh S650G
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2000 Bichon (Doby)

I have been thinking about blocking the radiator, but that's only because in the mornings, my drive isn't even long enough for me to get heat. In the afternoons, I still don't get to operating temp going home from work.

Since I have moved here (in the last few months) and been driving shorter distances, I am getting a lot more smoke out of my tailpipe. I blame the injectors getting gummy from not burning cleanly at OT very often. When I take my trips every few weeks, I get to do a nice italian tuneup and the exhaust cleans right up.

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My Primary Driver - '85 300CD - 4-speed conversion, 2.47 rear, lowered, euro headlights, rebuilding (not restoring so much)

Wife's - '08 Saab Sportcombi Aero

Riding a '03 Yamaha Warrior

If the thermostat is working properly then there is no reason for cardboard. All coolant continues to circulate only in the heater core circuit and block when its cold....nothing goes to the radiator. I've had mine say 65C on the gauge and was blowing good heat inside, but the upper radiator hose and radiator were stone cold....no flow until it reaches 82C. And that was when it was like 10F out.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

That is a VERY bad idea unless you live in northern Canada or Alaska. Truckers continue to do it out of old-superstition ignorance thinking it actually does something beneficial.

You still have the engine fan pumping cold air over the engine, road draft flowing under the engine and cold air coming into the intake.

AAAAH HAAAAAA! Then the debates and arguments about using a electric fan and a temp relay, and the cold air intake under the hood being a bad idea because it sucks in hot air, would be a good idea then. NO?

Card board is bad, but Peterbilt and kenworth etc... selling storm fronts for their trucks is OK??? Or that bad too???

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works