Car is running hot in traffic

Check for blocked air flow through radiator, you can get a lot of dirt and leaf matter clogging radiator. also, check between radiator and condenser as well. it sounds as it may be an air flow problem.

Radiator was flush and clean two times there is nothing like something blocked the airflow. I even changed the temperature sensor. one thing more I noticed but as per my mechanic he said me it normal but I do not believe him. The thing is that I have 87c thermostat the suction fan should start spinning at when thermostat open but in my car it start spin at 95c and stop at 93c and the speed is slow I feel that. second when I use air conditioner the fan do increase speed but it should be more faster I think and the last when I use full blast heater then the fan start spinning full speed very noisy like this in traffic temperature goes down to normal. now is it a fan problem I have doubt?

I have seen where the fan motor loose their strength and become weak not being able to pull the air through the radiator.

Here is a guide to show you what you are in for when changing out the fan motors.

https://www.2carpros.com/articles/replace-electric-fan-motor

and here is what it is like on your car (below)

I would change the thermostat out as well just to be safe.

https://www.2carpros.com/articles/replace-thermostat

Please let us know what happens.

Cheers, Ken

Hi yes this is the same suction fan above in photo,
I bought a temperature gun and what I figure out is while driving on highway high speed I stop onside of the road and check upper hose is 87c and lower is 82c this is good and now I tired idle the car for long time and checked the hose temperature upper is 90c and lower is also 90c suction fan is spinning and upper and lower hose are in pressure and because of too much pressure coolant not circulating properly at idle while opening heater temperature goes down to normal quickly is now radiator not doing his job to cool the coolant?

You can have some blockage like a plastic bag stuck in between the condenser and radiator?

I figure out the problem already it’s the suction fan not spinning on time and when it spin speed is slow need to be fast too to control increasing temperature. In my climate control there is secret menu in that option 10no blower control speed, in that I can see my suction fan speed running at 25% at idle but when I accelerate the speed increase but not much and then when I change the speed manually from there to 60% temperature goes down to normal at idle so maybe it kind of some sensor issue or it’s fan like fan need to be reprogrammed through computer??

Hi Farhan,

How long have you been using this vehicle and when did you start noticing this problem?

From what you have tested and the information provided I do not see any abnormalities as everything seems to be working within specs

When the thermostat opens, the fans would not start working immediately. It should start working only around the range of 90c and when temperature increases to 97c the high speed would be activated. The speed would reduce when the temperature lowers. If the cooling fan is not working at high speed all the time, cooling system is normal.

The cooling system works under pressure and with coolant in system, boiling point is is between 105c to 115c depending on condition.

K H Low

Hi KHLOW,

I bought this car last month from used car showroom here it’s a mecerdes e500 2004 Japanese spec, my friend have the same car and same model in his car temperature stay in middle which is 85degree it’s not moving up and down either ac is on or off and that the GCC Specs in United Arab Emirates. My car temperature stay on 80c which is 100c while I’m traffic but once I’m in highway temperature goes down to 85c..

HI KHLOW

Forget to mention before at cold start thermostat open at 87c and then the fan start spinning at 95c and stop at 93c, it’s starting winter now here the car is acting this way then what will happened in summer when it’s 50c hot this car can’t servive and one thing more as I know something is wrong with the car when the car temperature is at 98c I switch off the car and after 2mins switch on and see the temperature is at 103c so this is not good and normal

Hi Farhan,

There is nothing wrong with the vehicle just that the operating specs are wrong for your region. Over here our specs are similar with the Japanese and that is why I am saying the vehicle is ok. It is not a matter of reprogramming the system but rather a problem of replacing the hardware with the correct software. These ECM are non programmable as far as I am aware.

K H Low

Alright so that means in ur region or Japanese spec cars in Japan there temperature gauge is always quarter to 12? And can I know what is the boiling point of antifreeze 50 mixed with water? Before I gave the car in one garage they put all water in radiator air bubbles stuck in heater core and because of bubbles when my car is cold after 12hrs system is still under pressure

The boiling point of antifreeze ranges from 110 to 125 c depending on the concentration. For Japanese specs, the operating temperature is around around 93 - 95 c.

If you do not have any coolant in the system, it is going to run with a higher pressure and is not advisable.

Has coolant been added to your system?

We used to get overheating problem with European makes when they were imported used as the specs do not match. One of the things we did to overcome this was to replace the radiator with a higher capacity with better cooling efficiency. The thermostat is also replaced with one that opens at 82 c.

Maybe you can consider this option.

Yes the coolant was added, one of the bad thing about this car cooling system is closed system means no cap on radiator the cap is on revioser bottle and due to this I can’t check if the radiator is fully top up and the second thing about cooling capacity I read it’s 11.5quart but while refilling after draining all it was top up with two 4L gallons only..

Ya it won't be the same as the capacity because the system cannot be completely drained. Has anyone checked this engine for a blown head gasket? The problem could have nothing to do with the fans.

Here is a guide to help us.

https://www.2carpros.com/articles/head-gasket-blown-test

Please let us know what happens.

Cheers, Ken

Hi ken,

I was expecting it might be head gasket, the last 3 different garage I went they didn’t find any sign of head gasket failure.. oil was ok, not losing coolant neither engine oil, three time I flash the radiator and bleed properly with 50 50 mix coolant..and today I was in MB workshop they checked the fan operation and said me the fan should start spinning at 85c and stop at 83c but mine start spinning at 95c and stop at 93c something is wrong as per them so they did computer diagnose no fault except one (Can system fault).. as per them fan is ok and it’s speed also as per outside temperature fan will not speed up depend on outside temperature fan speed is increased, vechile speed sensor is also ok and as per refrigerant pressure when using aircon speed of fan is ok at idle... they suspect also head gasket but no sign of it then they suspect exhaust gas in cooling system which they can’t check And I try to find in auto spare parts shop they don’t have exhaust gas check in coolant device..

So is it possible when exhaust gas leaking in coolant it will delay fan operation by giving false ohms to cooling fan. Or maybe weak engine head?

And also for an example When driving temperature is at 85c normal and as soon I park the car ignition off and check after 15seconds I ignition swtich on and the temperature is at 88c overheat

Your results don't indicate a fault with the gaskets etc.

88 c is not overheating. When engines are turned off, temperature accumulates at top and the temp sensor at the top of the engine would register a higher reading. That is the reason most vehicle nowadays would have the cooling fan suddenly turn on after being parked for a few minutes. At 88c the fans don't turn on.

Your MB mechanics are using the specs for your region and not those of the Japanese. Have them check out the Japs specs. The Engine Control system would have to be remapped to make the fan comes on at a lower temperature.

This vehicle is equipped with a sensor to indicate when coolant level is running low and a warning indicator would show in dash so you don't need to worry about the coolant level.

Hi KHLOW2008,

Just yesterday I got my delivery (heat temperature gun) I examined it on two hoses after driving for 30mins , first the upper inlet hose 85dec and then strange to see lower outlet hose going to water pump is 88dec now what is this meant? I’m sure water pump is ok as checked by mechanics before I think it’s flow problem in block coolant jackets is blocked somewhere and that’s why at idle temperature jumps up slow slow up and once on highway speed circulation of coolant is ok but not on idle or traffic.. can coolant vapor block the flow in block or in head and is it a sign of head gasket or bad block or head ?

Blocked radiator core tubes often can't be cleared with a back flush, you will see water flowing, but that's no guarantee that you do not have a number of blocked core tubes, you will still get circulation but at a reduced rate, the only way to check this is to get the radiator removed and have the top and bottom tanks removed and manually clean the core tubes, this is done at a radiator repair shop, its a fairly common problem.

Radiator was removed and cleaned by removing plastic covers and after that two times flushed also I’m sure it’s not the radiator issue because the inlet and outlet hoses are same pressure and only the difference here is Lower outlet hose is more hotter then upper why!

It is not possible for the upper hose to have a lower temperature than the lower hose. Either the reading is wrong or you have recorded the hoses wrongly.

Hi KHLOW

Thanks for reply

The readings were correct there is no mistake
Remember I told u the car heater work normally because the car is having secondary water pump which circulate coolant through heater core when In used, from water pump one hose going to aux water pump, the new mechanic was way too experienced he find out my heater is blowing very very hot air when In used because engine water pump is not doing it’s job when at idle and that’s why lower hose connected to block is more hotter then upper.. I replaced the water pump and now my fan also start at 87c when thermostat open..
Before my fan start 95c coz ecm is confuse with fluctuation coolant and the mechanic find out this on oil cooler by heat gun temperature was coming low and high up and down.

The sensor will trigger fan automatically at 95c low speed and 104c high speed it’s rated on it but the ecm will trigger fan automatically by reading coolant sensor at 87c if no air in system and every thing in functioning properly. Very complicated

It sounds like a blown head gasket even though you have no confirmation. This happens from time to time becasue the test is only 75% accurate. This will pump unburnt combustion gases into the cooling system causing the heater not to work. You may have no other symptoms then what you have.

Ken,

I never said that my heater wasn’t working.. head gasket blown no way because 4 Mechnic confirmed me your car doesn’t have head gasket problem.. in my car problem was only at idle due to fan start late and second even if the aircon was on at idle fan run normally and it was still increasing my temp gauge slowly slowly up,, so in this car it want airflow problem it was coolant flow problem in block at idle due to bad water pump coolant not circulating.. and at cold start cap off when the car warm up thermostat open the coolant in radiator rises up normally but the level was not dropping after rise up so the mechanic said either ur radiator blocked or water pump is fault... after changing water pump the car is ok now.

Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers, Ken