johnny's E320

My temp needle on my '98 E320 reads just at around 80-95 C. I moves slightly (at 80 when I'm cruising and a bit higher in traffic) I know my 92 BMW's needle staying dead center unless it got hot and then it moved. Does your needle move slightly, or should it be in one place ALL the time if it is running according to specs?

Thanks all!

apl175

It's not unusual for it to move slightly while driving....
The temperature guage gets its signal from the CAN data bus.
The MB Service data indicates something to the effect of:
<i><br />
The display is a plateu display - the pointer stop at approximately 95C at temperatures between 95C and 115C. Temperatures in this range are not considered critical. The correct temperature is only displayed again from a temperature of 116C. This prevents the drivery from being disturbed by excessive needle movement in the display. The warning range starts at 116C. <br />
The coolant temperature sginal comes from the engine control module, and the guage is activated by a stepper motor.
</i>

johnny's E320

I was concerned since my BMW didn't move at all. I just had the belt tensioner replaced (included new pump, blade and other components) and I wasn't sure if that had anything to do with it. Thank you again..I like this new forum..I'm glad I joined!!

MBDriver

Yea, this is a pretty cool place to learn about ur car. I noticed this also when I first got my car also.

bamberger_1

If the needle moves slightly its ok. However if it moves slow to the "operating point" (under winter conditions) of around +80C, and moves beyond that while standing in a traffic jam and then driving again, and the needle falls below 80C , to slowly "recover" it could also be a sign of a bad thermostat in the coolant circuit which does not switch at the right temp.- points or does not switch at all. The same goes for the a defective (lame) fluid coupling for the main radiator fan, which may not have full operational speed anymore during high air demand, when driving under hot weather conditions and/or traffic jams.

rp718

Your temp gauge should not move more than 5C during normal conditions. Fluctuations typically mean a thermostat that is sticking. My 96 E320 stays rock solid at 82C once it has heated up. Even in summer stop-n-go with AC on does sit rarely go past 90C.

suginami

Actually, your temperature gauge should reflect the exact temp of the engine. It should move around if your engine temp changes.

This might sound stupid to most people, but MB's are unique. MB temp gauges tell you the exact temp of the engine.

All other gauges of all other cars - American, Japanese, Swedish, other German makes - have a buffer built in to prevent the gauge from moving. This is to prevent owners from freaking out if the temp moves away from the middle.

apl175

Well, let's not confuse anyone, the first reply I posted above comes directly from Mercedes Benz Service literature for 210 chassis vehicles. I believe however, this is only a recent "enhancement"

<i>
The display is a plateau display - the pointer stop at approximately 95C at temperatures between 95C and 115C. Temperatures in this range are not considered critical. The correct temperature is only displayed again from a temperature of 116C. This prevents the driver from being disturbed by excessive needle movement in the display. The warning range starts at 116C.

The coolant temperature sginal comes from the engine control module, and the guage is activated by a stepper motor.
</i>

suginami

Man, I guess you're right. Mercedes gauges in the past were always instantaneously accurate, but I guess in the W210 chassis they changed it.

It kinda makes sense because it scares people when the gauge moves so much.

In the summer months, the W124 forum is full of people afraid their car is running too hot when it goes to 100 degrees.

I guess keeping the temp readout constant at 95 degrees when the car fluctuates between 95 and 115 degrees keeps people from worrying.

BillB

I have had my 97 E 420 about a month. I observed an operating temp of 80 C, as the others above. Last week, I noticed the gauge moving upwards slightly during periods of turnpike driving - 75-80 MPH. I had not checked the oil level and decided that I should take a look. Sure enough, the car took 1.1/2 quarts to bring it up to level. Now, the oil temp gauge does not move off of 80 C during those periods of 75-80 MPH driving. It makes perfect sense, this is an oil temp gauge. Less oil means that the oil in the crankcase cycles more and builds up more heat.

By the way, the E420 V8 holds 7 quarts of oil.

MBDriver

This only happened when I turned the A/C on or if I drive for a cool while.

Mitias

My temp guage stays around 85 here in Dubai and only moves up a little after the A/C is on for a while. Talked to the mechanic here and he said it would be normal for it to be between 95-100C during the "warmer" months. I also have a 93 525 and it stays rock solid as well. I just wansn't used to it, however, after a little investigation, my anxiety was alleviated.

Also, I must agree. The message board is a great place. You will learn more about your ride here than anywhere else. I did the same with my e-34 and have saved time and lots of money that I turned into more mods for the car

Good Luck