SL/R230: 2004 sl500 running hot
11-08-2017, 01:50 PM
#1
Newbie
Thread Starter
2004 sl500 running hot
I am a new member here, I recently bought a 2004 sl500 and I notice that when I am in stop and go traffic, after the car has been running for awhile the temperature starts rising, it will get up to 100c, but when I am on the highway it stays at about 80c, I am thinking about replacing the thermostat, does anyone else have any thoughts?
11-08-2017, 02:41 PM
#2
Senior Member
Never had this problem with my '03 car but I wanna bet a fan engagement problem. See if it is on at idle A/C on full. 80 degrees while rolling same as mine but mine is 80-85 always. I feel this is a cool running car all the time. I really think the fan hardly runs at all with no A/C. I've never seen my gauge over 85 or so even on the hottest days with A/C blasting at a stop light. I'd like to guess the fan is not getting the signal to turn on or the fan may just not be working. We'll see what our other members chime in on this.
moretech
moretech
The following users liked this post:
Athlon572 (11-08-2017)
11-08-2017, 04:15 PM
#3
Senior Member
in my experience, thermostats fail in the open position to prevent overheating. Changing out the thermostat can't hurt and may help but my guess is not.. Mine runs 85-90c most times when idling. On the road it runs just slightly over 80c. Outside temp has a lot to do with running temp as well. During extremely hot weather, my car does run hotter. Changing the coolant is a maintenance issue but it may last 10 years or so. You'll want to go through your car and change all the fluids ie Brake fluid,Oil and filter,Differential fluid, ABC fluid & filter and Trans fluid & filter to establish a base line for future maintenance scheduling. Be very mindful of the ABC system as that is the one biggest weakness of the R230 above all else. Doing your due diligence before your purchased should have told you that. Anyway, welcome to the forum.
Good luck,
Bob
Good luck,
Bob
Last edited by mercy-me; 11-09-2017 at 07:12 AM.
The following users liked this post:
Athlon572 (11-08-2017)
11-08-2017, 05:26 PM
#4
Newbie
Thread Starter
More tech, Ok, so I checked further and the fan is not kicking on till it gets to 95 to a 100 and it doesn't stay on long, so I do believe it is a fan problem, it does kick on, but not soon enough or long enough, so I am thinking its the relay now.
Last edited by Athlon572; 11-08-2017 at 05:33 PM.
12-06-2017, 03:36 PM
#5
Newbie
Thread Starter
So, I checked the fuses, replaced the temp sensor, replaced the fan assembly, and the fan still doesnt kick on, so whatever gives it the signal to engage isnt working, at this point I dont know why it isnt kicking on.
The following 3 users liked this post by Rudeney:
12-08-2017, 11:33 AM
#7
Newbie
Thread Starter
But that's the problem, I don't believe the fan is kicking on, I have only seen it kick on once a little bit when it almost got to 100c. My concern is I know it's not normal for the car to get that hot on a regular basis, I believe the fan should be kicking on well before it does. In all my experience with cars the temperature gauge should stay halfway, if it gets to 3/4 of the gauge, something isn't right, it should not be varying that much.
Trending Topics
12-08-2017, 02:29 PM
#8
Banned
I don't know what temperature the fan is supposed to switch on. It may be c. 100 degrees. On my car they are not on at 90. W140 and R129 cars have auxiliary fans to assist engine cooling, and they do not switch on until the coolant reaches 103. Also, M-B sees nothing wrong with engine temperatures of 100 and stated so in a bulletin to their U.S. dealers.
There is a simple way to test the fan and its controls. Remove the connector to the coolant temperature sensor and insert a 120-ohm resistor of any wattage into the sockets. This will simulate a coolant temperature of c. 110 degrees and the fan should run.
There is a simple way to test the fan and its controls. Remove the connector to the coolant temperature sensor and insert a 120-ohm resistor of any wattage into the sockets. This will simulate a coolant temperature of c. 110 degrees and the fan should run.
The following 2 users liked this post by bobterry99:
Athlon572 (12-08-2017),
twinturbov12 (12-26-2018)
The following users liked this post:
twinturbov12 (12-26-2018)
01-24-2018, 03:19 PM
#10
Newbie
Thread Starter
Ok, so a quick update. I replaced the thermostat, that was the problem. I am not familiar with these cars, but I found out that the thermostats are 87c, I was assuming the 80c was the center of the gauge and that that is where it was supposed to be at, the factory thermostat states 87c right on it, as does the replacement, therefore getting above 80c is normal, running about 85-90c is normal, and the fan does not kick on till 100c. I wish I would have stuck with my instincts and replaced the thermostat in the first place, but now the car has new fuses, temp sensor and fan shroud, but all is good.
01-27-2018, 10:56 AM
#11
I'm new to all things Mercedes Benz and did experience a similar problem recently in stop and go traffic with an outside temp of about 50 F. This is what my manual said:
During severe operating conditions, e.g. stop-and-go city traffic, the coolant temperature may rise close to approx. 266°F (130°C). The engine should not be operated with the coolant temperature over 248°F (120°C). Doing so may cause serious engine damage which is not covered by the Mercedes-Benz Limited Warranty
I read in another forum that turning on the A/C even if the outside temp doesn't warrant it will activate both cooling fans and should help lowering the temp.
HTH
During severe operating conditions, e.g. stop-and-go city traffic, the coolant temperature may rise close to approx. 266°F (130°C). The engine should not be operated with the coolant temperature over 248°F (120°C). Doing so may cause serious engine damage which is not covered by the Mercedes-Benz Limited Warranty
I read in another forum that turning on the A/C even if the outside temp doesn't warrant it will activate both cooling fans and should help lowering the temp.
HTH
Last edited by arcom; 01-27-2018 at 10:57 AM. Reason: speling
01-27-2018, 03:02 PM
#12
Banned
07-03-2018, 07:03 PM
#14
Newbie
Join Date: Mar 2016
Posts: 7
Likes: 0
Received 3 Likes
on
3 Posts
89 560SEL and 94 SL500 , 2011 CL63 AMG
As the Owner of a 1994 SL500 for over 20 years I had never had an overheating problem until I developed a small crack in the plastic radiator tank in the top hose spigot. The net effect was a loss of pressure in the coolant system with a resulting lowering of the boiling temperature. I like so many others on this forum had never rally seen my aux fans kick in because I had never reached those temperatures. But now without pressure I suddenly was but by the time the fans kicked in the water was already boiling.
After doing a lot of reading and in particular the words of wisdom from Bobterry99 and his diagnostic information of the resistance values of the blue engine temp sensor I got to thinking. If this sensor is using the resistance value to turn on the fans then there is a very simple solution to 90% of the issues surrounding overheating and aux fans
Just purchase a 1K Ohm .5 Watt screw adjustable variable resistor. Solder it across the two pins of the wiring harness plug.
What this does is place a resistor in parallel with the sensor ( also a variable resistor by temp) and this lowers the effective resistance seen by the controller)
By presenting the value at around half way ( I set mine to 600 Ohm just using a standard multi meter) you can now adjust the value up or down to give you the cut in temp you want anywhere from 80 deg C all the way up to the original 110 deg C.
This means that for the cost of a $2.50 variable resistor we can all adjust the temp cut in point to suit our own individual circumstances.
The best part is if you operate in unusually hot areas you can bring the aux fans on earlier to assist.
In my case it let me bring the fans on as low as 85 deg C which meant while I took the time to fix the crack in the tank I could release the radiator cap to the first stop and the temp never went over 85 deg C so no loss of coolant and I could continue driving the car.
I have now fixed the crack and I am changing over to a waterless coolant that does not produce any pressure all the way up to 250 deg C so no strain on my radiator repair and I can just set the cut in temp of the aux fans to suit my ambient operating temperature
I can't believe such a simple fix wasn't introduced by Benz years ago to fix overheating in hot climates
Cheers
After doing a lot of reading and in particular the words of wisdom from Bobterry99 and his diagnostic information of the resistance values of the blue engine temp sensor I got to thinking. If this sensor is using the resistance value to turn on the fans then there is a very simple solution to 90% of the issues surrounding overheating and aux fans
Just purchase a 1K Ohm .5 Watt screw adjustable variable resistor. Solder it across the two pins of the wiring harness plug.
What this does is place a resistor in parallel with the sensor ( also a variable resistor by temp) and this lowers the effective resistance seen by the controller)
By presenting the value at around half way ( I set mine to 600 Ohm just using a standard multi meter) you can now adjust the value up or down to give you the cut in temp you want anywhere from 80 deg C all the way up to the original 110 deg C.
This means that for the cost of a $2.50 variable resistor we can all adjust the temp cut in point to suit our own individual circumstances.
The best part is if you operate in unusually hot areas you can bring the aux fans on earlier to assist.
In my case it let me bring the fans on as low as 85 deg C which meant while I took the time to fix the crack in the tank I could release the radiator cap to the first stop and the temp never went over 85 deg C so no loss of coolant and I could continue driving the car.
I have now fixed the crack and I am changing over to a waterless coolant that does not produce any pressure all the way up to 250 deg C so no strain on my radiator repair and I can just set the cut in temp of the aux fans to suit my ambient operating temperature
I can't believe such a simple fix wasn't introduced by Benz years ago to fix overheating in hot climates
Cheers
The following users liked this post:
twinturbov12 (12-26-2018)
