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I've only had my 2001 SLK for about a month now, and I noticed that when sitting in traffic the temperature gage starts rising -- not into the danger level, but certainly above the mid-range level. For my other cars, the temperature never changed much once the car was warmed up. Is this normal for SLKs to run warmer in slow traffic or should I have this checked out?

Kenneth
 

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2002 SLK 32 AMG, bone stock. 1987 190E 2.3-16 valve (destroyed). 2005 E320 new toy.
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What temperatures are you running...

Anything up to 100 degrees C is in the normal range and not a problem. If you run much higher then that, you might want to check the radiator to see if it's blocked up. Assuming the radiator is clear, you might want to have it checked by a good mechanic.
 

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I believe somebody ?Kuhl? had a similar problem - they replaced the thermostat and the problem went away. But do a search - i am not sure if i remember it right.
 

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98 SLK 230
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My temp guage is normally around 80, but when stuck in traffic it will rise a bit to around 90. I also found this odd, since other cars I've had the temp. doesnt change.

So, I think this is normal. Although, make sure you replace you radiator fluid once every 2-4 years. If this has not been done on your 2001, go ahead and do it.

Cheers,
Pat
 

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2002 SLK 32 AMG, bone stock. 1987 190E 2.3-16 valve (destroyed). 2005 E320 new toy.
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Always a brilliant come back hey Linh.....

You'll always be a hero in your own mind..[:D][:D][xx(]
 

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1999 SLK 230- RED
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Mine did that....ran around 80 but would creep up to 100 in traffic snarl. They first replaced the thermostat. Next it was the radiator pressure cap that got replaced. It still does it but the rate of climb on the temp is much slower now. I think it might be due to the fans not comming on early enough in the temp rise cycle, thus allowing the engine temp to get a head start on the cooling system's ability to cope with above normal temps. Course the engine at idle rpm is lean for emissions purposes which leads to increased engine temp,and when you speed up, the engine goes richer on fuel mix and the speed of the car ramming cool thru the radiator helps the darn thing cool back down right away.

If you want more heat soak capability, add an inline transmission cooler in the line going from the tranny up to the radiator. In that manner you can pull off some load on the radiator, but the radiator heat will warm back up the tranny fluid (auto trannies need oil that is not too cold nor too hot....kinda like Lil Red Riding Hood and the porrage) before it completes its cycle back into the tranny. When most engines are running 230 and above, your auto tranny fluid is over 300 degrees, and they don't like that and will discolor the fluid although the engine has never been excessively hot. Changed my tranny fluid at about 50,000 mi. and it was too discolored and smelled as if the tranny had been hot. These new automatics don't have a lot of fluid capacity, and any heat can run past the tranny fluid heat soak capability (not as much mass to heat up before the temp. gets critical).

Regards
 

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MAX BLAKELY - 3/17/2005 5:54 PM

auto trannies need oil that is not too cold nor too hot....kinda like Lil Red Riding Hood and the porrage
Max, it's been a while since you had young kids...it was Goldilocks and the three bears that had the porrage issues, Lil Red Riding Hood had problems with a wolf, LOL. [:D][:D][:D]
 

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2006 SLK-55 AMG
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I don't know this to absolutely be true, but I *think* that the electric radiator fan is speed controlled by the finned heat sink device on the left front fender, and its speed is supposed to be proportional to the amount of cooling needed. Maybe someone with previous experience with the fan controller can elaborate?

If this IS true, then the sensor that reads the temperature of the coolant and decides how much fan cooling to add could also be at fault, as could the fan control module or fan. If the guage is going UP, it likely means the coolant temperature is going up also, even if the exact temperature reading is not correct or varies from one person's guage to another's. Most pressurized systems with glycol do not BOIL until the localized hottest spot in the engine is over 250 deg Fahrenheit (121 deg Centigrade on the guage), so a reading of 100C does not necessarily signal an emergency situation.

If the guage starts going WAY up in a long traffic stall, you can always open the roof and turn on the heater to temporarily add additional cooling.[:D]
 

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99 230 SLK Sport
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My needle moves too. At first I was worried but after letting the car sit and idle in hot weather (not much of that in California lately), the car never seems to go above 100. I don't see why the temp should fluctuate so much between cooler Highway driving (under 80) and the higher (100) when at idle. Do any of you with a stock 230 have a temp needle that stays at the same level all the time? My bimmer warms up and the needle never moves so the SLK still makes me a little nervious in traffic.

I agree with the previous post, the location of the themostat on our 230 makes it one of the easiest to change I have ever seen. I doubt this would take longer than 15 minutes!
 

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Mine too. 80 to about 90 depending on outside air temperature and pace of traffic. Now I'll have to watch it more carefully for a while.
 

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MrLan1 - 3/18/2005 12:43 PM

My needle moves too. At first I was worried but after letting the car sit and idle in hot weather (not much of that in California lately), the car never seems to go above 100. I don't see why the temp should fluctuate so much between cooler Highway driving (under 80) and the higher (100) when at idle. Do any of you with a stock 230 have a temp needle that stays at the same level all the time? My bimmer warms up and the needle never moves so the SLK still makes me a little nervious in traffic.
Many manufacturers "numb down" the guages so that worry wart customers will not see fluctuations and panic every time the needle moves. Mercedes doesn't do this to the extreme. Don't worry about it unless it takes off well above 100 C. There HAS to be an increase in temperature to trigger additional thermostat opening and fan speed increase; without this "signal" of higher temp, there would be nothing to trigger the response to make additional cooling actions occur; its basic signal theory. If you don't see needle movement in other cars, its because they have numbed the guages, not because temperature changes are not occurring.
 

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99 slk 230 sport
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YellowSLK230 - 3/18/2005 2:43 PM

Many manufacturers "numb down" the guages so that worry wart customers will not see fluctuations and panic every time the needle moves. Mercedes doesn't do this to the extreme. Don't worry about it unless it takes off well above 100 C. There HAS to be an increase in temperature to trigger additional thermostat opening and fan speed increase; without this "signal" of higher temp, there would be nothing to trigger the response to make additional cooling actions occur; its basic signal theory. If you don't see needle movement in other cars, its because they have numbed the guages, not because temperature changes are not occurring.
I agree with YellowSLK230, I have never been bothered by the fluctuations, similar to my old 944 may she rest in peace. My wife's Dodge never changes and I had always assumed they tweaked the gauge.
 

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2002 SLK 32 AMG, bone stock. 1987 190E 2.3-16 valve (destroyed). 2005 E320 new toy.
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The "problem" is actually the location of the temp. sensor....

The sensor doesn't only pick up the block temperature, it picks up the temp of cooler water exiting the radiator as well. The end result is that the temp gauge reads sometimes wildly fluctuating numbers. Not to worry, as long as you don't go more then a few degrees over 100 (say 105) your OK. The fan will kick in at that point. The normal operating range is 80 to 100 degrees C, and these cars will use it all.
 

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Discussion Starter #18
My friend also has a black SLK black (2002)(he boughht one days after I bought one -- he was impressed after he test drove it). Well anyway, I was in his car yesterday, and we were in heavy, slow-moving traffic for almost an hour on I-95 hear DC, and I looked over at his temp gauge and it was on 100. From the responses of others to this thread and my own observations, this seems to be a normal phenomenon for SLKs.
 

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Discussion Starter #19
Just got back from a B Service, and I asked the senior tech guy about the temp running high in traffic, and he said just wait until its 98 degrees in the summer. He said it is normal for SLKs, just as long as it does not go into the danger red area.

Kenneth
 

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Hey Bruce!

Maybe if you ask real nice, Linh will explain to us how to "squek on a coolant hose"?
 
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