I decided to take my car to a very good independent that I have known for over 5 years. (The MB dealer already told me that they could not find the problem.) I explained what was happening and how the temp gauge would rapidly rise when standing still. I asked him to change the water pump and he did today with a brand new one. He confirmed back to me that it was still running hot and could not determine what was causing this as everything else seemed to be fine. He did say he will investigate more into it tomorrow.
I guess I don't know what to do next.
So far I changed the following:
New Fan clutch
New t-fitting at firewall
New Radiator
New Radiator Cap
New Water Pump
New Upper and Lower Radiator Hoses
New Temp Sending Unit
New thermostat
I'm going crazy trying to figure out what could cause my engine to heat up so fast at low rpm??
Could this be an air/fuel issue (running too lean)?
Timing too advanced?
I really like this car but don't know what to do next.
Has anyone experienced a car running hot due to something unrelated to the cooling system??
Very frustrated and ready to give up.
Hynek
__________________
1995 S500
1990 300E (Sold)
"Pay attention to the engineering of the past, many problems have already been solved" - Unknown
With all that do you think it's possible that there is a fault with the cluster, I'd say it's pretty unlikely being that 1995 has the newer cluster but you never know.
First, take a deep breathe and relax. Your Mercedes is going to be OK.
I went through the same panic attacks with my vehicle about a year ago. Same issues. Ran around 100C at speed with temp running up to 117C in traffic on very hot days. Never any hotter though. I did a lot of study on coolant calibration, sensors, fan relay gauge accuracy, etc.
In the final analysis I foung my gauge was running around 5-7 degrees higher than the actual coolant temperature. It was also non linear. I spent a month finding out why. The gauge in the instrument cluster is quite accurate as long as its receives a regulated voltage from the voltage regulator IC. Anyone who has experienced the problems with the mercedes instrument panel knows what I am about to say. The regultor wasn't working properly. Why was I not surprised?
In conversations with the Mercedes techs, it was agreed that coolant temps varied widely from car to car and were NOT a problem unless the temp went into the red zone. Their advice? Don't worry about it.
You should put your car in idle on a hot day with the A/C on. Let it run. If the temp does not intrude into the red zone, you're fine.
Now, go have a beer.
PS. Anyone that needs to discuss techniques for coolant temp calibration is free to ask. I've paid my dues on this.
Ken
__________________
1995 S320 -- built like a tank.
Location: originally:West Germany, now reside Central Florida
Posts: 168
Coolant system anomolie es going to be found!
Yes there are air/fuel and timing that can be an issue... both are related to feedback from sensors though, etc. Please do not stop investigation of coolant system... please consider following...Dutch
Are we sure the temperature reading you are getting es valid?
Has anyone ran a T type probe into the temperature sensor hole and ensured there es no corrosion and gauze buildup en the area. The only times I have noted this has been a circulation issue.
When running above idle there es plenty of pressure, etc. At idle there es minimum and flow can be restricted. What happens with temperature at idle when you turn on the cabin HEAT to full? Does the temperature lower? perhaps there es another restriction you and others are missing? I would not stop investigating the coolant system yet.
Has the backup coolant circulation pumps' operation been verified?
Sincere regets we all am not closer.... myself and my other mechanical MB technicians are very interested en thes anomolie.
If all the above are fine and no other incidence of temperature noted at , above or very near the RED zone. Then Dutch es en agreement with above and GO have a few beers (give friend keys) just keep an eye on things, should be fine!!!. ENJOY your Benz! You have covered all the Bases as I hear alot en my shop!
Regards....Dutch
Quote:
Originally Posted by 1995S500W140
Hello -
Not sure but I checked readings at position #6 on the HVAC and it also indicates a rapid climb.
Hynek
__________________ retired 32+ years: Mercedes Benz Technician
Sinndelfingen Facility Ein gut aufrechterhaltener Mercedes wird ebenso ruhig laufen wie eine Nähmaschine viele Jahre lang!
Last edited by Mercedes Mechanix : 10-24-2007 at 09:46 AM.
Here is where we are. Replaced practically the entire cooling system. Big cash, a lot of my time and my wife thinks that I am obsessed with the temp gage. I also purchase a non-contact pyrometer to verify and drove many miles with the sensor at position 6 on the climate controls giving me data which I recorded below.
Ambient Air Temp (50 to 70F)
Coolant Temp as recorded at position 6
It would be great to know if any of you have driven your 140's with position 6 active and watched the readings. Do these seem OK or are they higher than you have seen?
Those seem fine, as an exercise go find out what your thermostat should be, is it 80C or 92C? I'd say anything under 100C is to be ignored unless it's more like 60C which points to a problem with the thermostate.
In my experience with my w140 it's 89c to rarely 102C in stop/go traffic in 30C weather. I've only seen 115C in the mountains under heavy throttle on a 7-9 percent grade at 1000 meters altitude. I'll note my 92 300TDt hit 105C under full! throttle at 110 km under the same mountain conditions, normally it sits at 85-90C under all other conditions,.
1995 S500 STILL Running Hot 
Coolant system anomolie es going to be found! 
Linear Mode
