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2004 ML 350 w163
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56 Posts
Discussion Starter #1
Hi guys, aftwr not finding an answer in forum, allow me to ask a dumb question as newbi:
The operational temp for coolant and showed in gauge is little below the 100 line in gauge, but when in highway cruising in little effort or fresh ambient, the lever drops to 80 fast and goes back to previous with some effort in engine.....is that normal or a sign for some issue? My other MB sedans same period, do not fluctuate so much...this baby is E240 2.6L V6 w210 2000
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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3,667 Posts
That's normal. MB has real temp gauge, instead of dummy gauge that's in most other cars. Car will vary temps depending on load and cooling, very normal.
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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6,368 Posts
Make sure your radiator fan works properly. Some fluctuation is OK but not almost 20 degrees C. The thermostat opens at 87. A failing thermostat can cause such fluctuations. If you have not serviced the cooling system for a while, maybe you should.
 

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E320/E250 Bluetec Ford F350 6.7l
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36,492 Posts
What weather do you have in your country right now?
When few degrees variations are normal when you have real gauge, 20 C raise and drop with small load variations is not normal.
Check your fans to start with. If you have digital climatronic, you can observe real engine temperatures on it.
 

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2004 ML 350 w163
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56 Posts
Discussion Starter #5
weather here is ending summer in transit to autum, so hot days and cold evenings, but these variations ocurrs in same trip, if im going downhill idleing or fast flat highway, marker drops to 80, if I start to accelerate or uphill, rises to almost 100, always below 100 steady.
 

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w163 02 ML500 W210 97 E50Amg w202 99 C230K w124 - need more space, time to build again
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2,412 Posts
weather here is ending summer in transit to autum, so hot days and cold evenings, but these variations ocurrs in same trip, if im going downhill idleing or fast flat highway, marker drops to 80, if I start to accelerate or uphill, rises to almost 100, always below 100 steady.
jesbmw,

As relayed to you in your other posts, "you are within the normal range".

You dont need to post the same Q on multiple threads.....

 

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E320/E250 Bluetec Ford F350 6.7l
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36,492 Posts
weather here is ending summer in transit to autum, so hot days and cold evenings, but these variations ocurrs in same trip, if im going downhill idleing or fast flat highway, marker drops to 80, if I start to accelerate or uphill, rises to almost 100, always below 100 steady.
You need to be more precise than that. "Warm days" for me are 120F/50C, so is it the same for you?
You need to help us help you with proper feedback. Did you confirm the temperatures with digital meter as I suggested?
 

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1998 E320s sedan and wagon
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994 Posts
Possibly the radiator fan isn’t engaging or isn’t engaging properly. IIRC it should be blowing to some extent at idle when the engine temp gauge is above 95*C. Assuming single electric fan begins the radiator. Or do you have a mechanical clutch fan on the water pump pulley?

Sixto
98 E320 wagon 197K miles
 

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2006 ML320 CDi, 3.0-litre Diesel 7G-Tronic
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241 Posts
Take the car for a 20 minute drive.

Then let your engine run on your driveway, the fan may be running or should eventually run to cool the radiator. Switch off the engine.

The fan should continue to run for a few minutes then stop when the rad temperature drops.

The only reliable way to test your thermostat is to remove it, make sure it's closed, and drop it into boiling water to see if it opens.

So you may as well replace it with a new one, they are cheap.

.
 
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