I usually cruise in my 300D on the highway between 70-75mph. Yesterday I was in a hurry to get home and was sitting between 80-85mph. I noticed the engine temperature crept up to 90-95 degrees from its normal in the low 80's. Ambient temperature was 90 degrees, AC on, coolant level normal.

Is this unusual?

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1990 300D - 171K miles
http://nrl073.googlepages.com/DSCN66...646-medium.jpg http://nrl073.googlepages.com/DSCN66...654-medium.jpg

Doubtful. On your car you need to be VERY careful about overheating. Perhaps time for a new thermostata and a flush?

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

IMO 90 to 95 degrees is nothing to worry about.

That said, winmutt is right. You need to be very careful not to run that car hot! Just keep an eye on her.

....your radiator is not rejecting the additional heat.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

Not so much on the 90's 2.5L as was on the 87's 3.0L.

I'd look into doing an external radiator clean-out (Remove the radiator and blow/wash out the fins), citric flush and t-stat if it's been a few years since it was last done.

Check the fan clutch. Get the engine good and warm on a hot day and then open the hood and spin the fan by hand (with it off of course)... it should feel tight.

If it just freewheels with no tension on it at all then the fan clutch is shot.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

my cars engine temp goes up to like 85-89, i try to keep it under 90, but was wondering if its okay for it to go up higher? the gage goes upto 120. also is tha the way to check the temp of car? or is there another gage im missing?

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I can do 111mph with no gas, no oil, and no power staring, threw traffic. Can anyone else do this one a 20 year old car? I think not.

I used to have a g35, now I took this Benz and made it quicker, more agile, and much roomier then the g, **** Japan rock the German engineering.

Fan clutch shouldn't make a difference at the speeds he was traveling.......

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

Agreed. Clean the rad.

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2009 VW TDI Jetta Sportwagon 172k miles (rear-ended harder than Elton John on 8/4/13. Total loss)

1991 Volvo 240 142k miles (T-boned by a stop sign runner. Total loss)

i would start out troubleshooting with a digital laser thermometer instead of throwing parts at it- been there

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Brian

82 300d turbo 164k - passed on
83 sd - passed on
04 civic hybrid - DD
06 GTO for sale - passed on
84 VW Rabbit Diesel 4dr.- passed on
94 S350D - DD
94 S320 - soon to be DD

I would go with an even cheaper method of measurement than a laser thermometer, a candy thermometer. That will definitely tell you how hot your coolant is! You can get one for less than $5.00 at any grocery store! Been there, done that!

any 124 just runs hot for some reason. having no bottom plate underneath the engine has to do with that too. You have that plate?

Didn't read the speed, sry. Mine's been such a problem that's my first automatic suspicion.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

Has anyone tried Purple Ice made by Royal purple? I think its like that pink wetter to cool the coolant more.

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Rick & Michele in California
1985 300SD Turbo Deisel
300,000+ miles

1963 Mercury Meteor Stationwagon
1959 Montgomery Ward Silver Pigeon Scooter & matching bicycle
1974 IH Scout 4x4

If the cooling system is healthy you shouldn't need anything beyond 50/50 coolant and a non-acidic pH level.

If you need to try gimmicks like water wetter additives and drilling holes in the t-stat, there are other cooling issues that need to be fixed.