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1992 300CE, Engine M104, (2002 E320 4matic Wagon—Retired)
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329 Posts
Discussion Starter #1
So...I have been trying to troubleshoot this temperature issue. The car was in the shop for some suspension work and I mentioned the issue: high coolant temp at stop and go traffic gets close to a 100, but does not quite hit it. The temperature goes back to above 80 at highway speeds. Thermostat got replaced...Coolant is flushed...The issue is still here. The question is is this normal? (take a look at the photo)

Many other members have mentioned similar issues...Do these cars run hot? I know that the thermostat opens fully at 95 degrees...But isn't this temp supposed to be somewhat stable? Any thoughts would be greatly appreciated.
 

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2001 C320 W203 Black on Black. 1997 E320 W210 Silver (RIP). 1995 E320 W124 Pearl Black.
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595 Posts
That look normal to me, both my 95 and 97 stay the same spot as yours, as long as it not pass the bar above I would not worry even if sometime it creep up and came back down when traffic came to snarl and gained speed later, if it getting close to 120 mark then it would be concern to check the thermostat and the life of the coolant.
Hope this comfoort you a bit.
 

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'01-E320 & 02-ST2
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Kmani1 ducks, and I jab. ;)

I am a bit more concerned and consider it closer to outside the normal band.

Does the 4matic variant have a fan clutch and electric fans? I'd verify that whatever fans you have are working properly. If they are and you know the cooling system has been properly mantained, then I'd feel more comfortable about it.
 

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2005 W215 CL500
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I don't suppose you have the full ACC?

If you do press REST 'till the display changes. Then press the left hand auto adjuster until 6 is displayed on the left. The reading on the right is engine temp. 87oC is about right.
 

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1994 E320 Wagon,1999 E320 Wagon,2000 E 320 Wagon, MGB Track/Rally, ,1988 300E ,more....
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6,019 Posts
THE T-STAT

IS FULLY OPEN AT 87C your info is slightly a kilter ;)
If the fan operates properly you are just on the nearly but not really high end of the normal range.
My opinion:D
Or add a botttle of redline water wetter and chill
 

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2001 E320 - Brilliant Silver/Ash: 107,000+
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17,193 Posts
That's a little higher than mine usually runs and although it varies up and down it has never hit 100C. Could it be that the 4matics run a bit higher because the engine is powering both axles?
 

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1997 E320, 1997 S320
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dude, imo you have been chasing ghosts and wasting money for no reason. your temp is normal. temp will go slightly above 90C in traffic and move back right above 80C in highway. regarding the auxillary fans, even if you had one know that auxillary fans don't kick in until 105C so that is not your issue. imo most important part of auxillary fans is when they kick in when ac compressor pressure builds up to lower it.
one thing is for sure, if your coolant mix is higher than 50/50 (coolant/h2o) than you will experience slightly higher temp. it's not like mechanics will use graduated cylinder when measuring the coolant mixture, they just dump it in there by eye approximation. i think i asked you a few weeks ago to double check on that, coolant tester is $2. redline watter wetter that ohlord mentions will problably lower temp a couple of degrees, but it also leaves an oily residue on the reservoir. imo water wetter is more for racing applications where no coolant is used but just watter.
good luck
 

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1992 300CE, Engine M104, (2002 E320 4matic Wagon—Retired)
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329 Posts
Discussion Starter #8 (Edited)
I had them check the fans. The fans seem to be working fine (thats what they say).

I am more suspicious of the radiator fan as it was probably disconnected for a water pump job, and this problem started happening after that. It has been about a year plus. I wonder if it is kicking in, but not spinning fast enough. I did do that engine stop test where it seemed to rotate about 2-3 times after the engine was turned off.

Coolant was replaced last year and again few days ago with the thermostat. Here is the Q though: I just payed for a job that was not really necessary since the thermostat and coolant were not the culprit. They keep saying, it is working normally. But, I disagree.

Or could it be the water pump or radiator? It only heats up in stop-go traffic. When I force the fan on the temp goes down.

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tirona, I have one of those testers...I will do a test. I get a bit nervous when that needle goes up to near 100 degrees...

the water wetter thing...I am a bit weary about additives, but I will look into it...
 

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R230 SL350 Presnt, Past - W208 CLK230K 2000, W203 C Class, W202 C Class, W210 E Class, W201 190E
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I have had 190E, C-Class W208, E-Class W210 and now CLK W208 and they all behave the same with regards to temperature and the image you sent is perfectly normal. It will sit at 80oC on driving normally and go to the next bar up around 90oC to 100oC when in traffic and racing. Thats the way it is.
 

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1992 300CE, Engine M104, (2002 E320 4matic Wagon—Retired)
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Discussion Starter #10
In my case the needle actually goes up even higher...close to the 100 degree mark...
 

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E-ZGO 53 HP., 99 E 430 sport, 04 E55 AMG, 2008 Tahoe LTZ Sold Porsche to Brother
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So...I have been trying to troubleshoot this temperature issue. The car was in the shop for some suspension work and I mentioned the issue: high coolant temp at stop and go traffic gets close to a 100, but does not quite hit it. The temperature goes back to above 80 at highway speeds. Thermostat got replaced...Coolant is flushed...The issue is still here. The question is is this normal? (take a look at the photo)

Many other members have mentioned similar issues...Do these cars run hot? I know that the thermostat opens fully at 95 degrees...But isn't this temp supposed to be somewhat stable? Any thoughts would be greatly appreciated.
In your pic the temp is low. In my car on a 60 degree day the needle stays at the top of the 8 on a tangent. On a 90 degree day in heavy traffic with A/C on it will go to just below the 100 mark. Yours sounds normal.
 

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'01-E320 & 02-ST2
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I had them check the fans. The fans seem to be working fine (thats what they say).

I am more suspicious of the radiator fan as it was probably disconnected for a water pump job, and this problem started happening after that. It has been about a year plus. I wonder if it is kicking in, but not spinning fast enough. I did do that engine stop test where it seemed to rotate about 2-3 times after the engine was turned off.

Coolant was replaced last year and again few days ago with the thermostat. Here is the Q though: I just payed for a job that was not really necessary since the thermostat and coolant were not the culprit. They keep saying, it is working normally. But, I disagree.

Or could it be the water pump or radiator? It only heats up in stop-go traffic. When I force the fan on the temp goes down.

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tirona, I have one of those testers...I will do a test. I get a bit nervous when that needle goes up to near 100 degrees...

the water wetter thing...I am a bit weary about additives, but I will look into it...
Personally I'd never use an additive to mask an underlying problem. That's like pancaking makeup over zits instead of eating better. ;)

The fact that it started after work was done is really, really suspicious. If it didn't do it before, but does it now, then that's enough for me to explore that. And the fact that the temp comes down when the fan comes on tells you that there's nothing wrong with the radiator or the water pump or the thermostat.

Either the fan is not working properly or the temp sensor it relies on is malfunctioning.
 

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1992 300CE, Engine M104, (2002 E320 4matic Wagon—Retired)
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Discussion Starter #13
"That's like pancaking makeup over zits instead of eating better. "

Nice quote! I guess I will ask them to check the temp sensor and fans again...It is funny how many people think it is normal though...Maybe it is, and I never noticed it before...Or, a lot of people have the same issue.
 

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^^^ I still have to disagree. If it *does not do this* when the fan is on, then that's the problem. My car never varies very much even when I'm in Phoenix in the summer. But that's because the fan works properly.
 

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1992 300CE, Engine M104, (2002 E320 4matic Wagon—Retired)
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329 Posts
Discussion Starter #16
"you didn't notice it before because most likely your thermostat wasn't good to begin with, but a new thermostat fixed the issue."

Actually I think I just wasted a bunch of money going along with the thermostat replacement + coolant flush. Back to square one. It was behaving exactly the same way before the flush+thermostat replacement.
 

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1997 E320, 1997 S320
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Actually I think I just wasted a bunch of money going along with the thermostat replacement + coolant flush. Back to square one. It was behaving exactly the same way before the flush+thermostat replacement.
i wasn't talking about the second time you replaced the thermostat, but the original one you replaced along with the water pump, that's the one i meant it was faulty and not allowing to reach "fully hot" temperature. so both the coolant and thermostat you just replaced were good to begin with.
 

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E320/E250 Bluetec Ford F350 6.7l
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I am always amazed how much and how long some members can talks about the issue that takes about 20 seconds with infra red thermometer to diagnose properly
 

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1992 300CE, Engine M104, (2002 E320 4matic Wagon—Retired)
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Discussion Starter #19
Kajtek, how do you diagnose this with an infrared thermometer? I'll try it out.

Yep...I agree that the work was not necessary and it was a waste. I need to talk to the people at the shop.
 

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E320/E250 Bluetec Ford F350 6.7l
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I posted my idea of cooling system troubleshooting before, but let's try again.
Beware that some symptoms can show as the same defect and needs to be verify by actual removal. Typical is stuck close thermostat and broken pump impeller.
So first thing you have to recognize components and coolant flow. In MB I know the thermostat is on coolant return line, what is quite different than most of the cars. Than radiator flows the coolant sideways. You have to figure out what side is hot and what cold.
So at the moment your engine shows higher temperature -with it running confirm that the radiator on hot side is having the same temperature what engine head.
Than radiator temperature should gradually drop and return fitting (thermostat housing) should be way colder than the head. If whole engine is very hot and radiator way colder, that means there is no good coolant flow and you check the pump and thermostat.
If the radiator is all hot with fans running, that means the radiator has lost it cooling efficiency.
The thermometer also can diagnose fan clutch, but that we can discuss later.
 
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