First thing to confirm it is actually overheating, if you have no water loss or other symptoms. then it probably is not!

Get a thermal imaging camera or thermocouple and reader and check the actual temperature of the engine temperature sender. This will confirm if you have an issue OR the engine sender or gauge are at fault.

Good luck

 

I don't have coolant loss or other symptoms.
I will try to get the thermal imaging camera, just want to be clear where i need to check the temperature? Is it there where temperture gauge is?

 

Yes. I would check it where your red circle is or anywhere along the top of the head and maybe deduct a couple of degrees C as the reading will be external. It will certainly give you a very close guide!!

 

Nice clean engine.
My 400E is also running hot until I drive about 80 mph, then cools fine. That does seem like a fan clutch issue. hmm.
Anyway, thought here is to check the coolant for any traces of oil or sludge. I suppose this could come from the trans cooler lines or oil/water heat exchanger. The idea is that this sludge is coating surfaces and not allowing good heat transfer between the coolant and the surfaces. This is actually mentioned in MB manuals. I bought and added Blue Devil Coolant flush yesterday, we'll drive on that for a while. Fortunately the weather is cooler this week.

 

Define "hot". "Hot" is a broad term with very little meaning.
What makes you believe it's a fan clutch issue?

You've got an m119.
This is not the same as the m103/m104s
Just asking; what made you decide to use a 3rd party coolant flush?
What makes you believe you have coolant sludge issue?

You should be starting a new thread on your specific problem.

 

What else i noticed that after i changed my thermostat and coolant, when the temperture rise above 100C the lower pipe from thermostat is quite cold, much colder then the upper pipe to thermostat and also the radiator, uper part is warm but lower part of radiator is cold, could it been that thermostat is not opening or i have air in cooling system? Today i will try to change cooling system gauge, will see if it makes any changes.

 

I think you may have solved your own problem. You need an open/functioning thermostat and a working water pump to create a loop from the radiator to the engine. If you have a coolant hose that you can touch with your hand when the car is at operating temperature, then one of those two items isn’t working or, as you said, potentially air in the system. I think the air would work it’s way out eventually if the water pump and thermostat are working. Be careful that you don’t cook your engine.

 

Is there any easy way to test water pump?

 

Water pumps usually leak when they fail rather than just stop pumping. I usually squeeze the big coolant hoses and can tell if there is coolant in there or not. If they feel empty, then there could be air in the system.

On some cars, you can take the thermostat out TEMPORARILY to test if the pump is working and circulating coolant. At least you eliminate one possible problem if all of a sudden the car runs cooler at full operating temperature. This is harder to do when it’s cold because the engine would take a long time to get up to temp.

Some thermostats have a little hole with a check valve thing that needs to be oriented a certain way so that air and a bit of coolant can get through to prevent air entrapment. I had this on an 80’s Volvo, but I can’t say if that’s the case on these MB engines.

Is the coolant a 50/50 mix with water? The coolant itself is not as good as water as a heat transfer fluid.

 

I dont have any leaking. And the hoses feel good, not too soft and when in operating temperture they feel alright. And yes, i filled 50/50 coolant with destiled water.
Today I changed the coolant temperture sensor, while driving home the temperture was OKish.
Some day I will drive a bit longer so i can see if the temperture will stay ok or will rise again.

 

distilled water
not just any tap water ====> deposits galore
but hey, it's your ride, your decision

Mercedes OEM coolant - dis stilled water

While ordering some parts online I came across Mercedes coolant, which I know is obviously best to use in these cars (especially as Kent from MercedesSource teaches us). In newer cars the coolant is pre mixed, is the Mercedes coolant already pre mixed or do I also need to mix it with dis stilled...

www.benzworld.org

 

Citric acid flush before going further. Do not pass go. Do not collect $200

 

You just might have water pump with a plastic impeller. And after the first over heating you have melts the impellar down .Then the coolant will no longer circulate anymore .

 

I always test a new thermostat in a pot of boiling water on the stove, with a good thermometer, to make sure it opens at the correct temp, and is fully open at the correct temp. Why test the new thermostats? Because they can be bad right out of the box, and the test is simple enough, if you can get the right technical information about the correct thermostat for your car. From memory, the t-stat for my OM603 engine starts to open at 82 deg C and is fully open (8mm?) at 90 deg C. Compare test of new and old t-stat, and know for sure if you are replacing a bad t-stat with a good t-stat. Don't just test the opening, but also the closing, to make sure that as the t-stat cools down, it closes correctly too.

Where to get the technical specs for your car? From the Technical Data Manual for Passenger Cars that covers your car. MB published these, and they are chock full of technical data for all the cars made in the covered period, like which engines and which transmissions and which differentials were installed in which models, capacities, torque values, test values, spring / pad combinations, acceleration numbers, shift points, towing capacities. They are like the Cliff Notes version of the service manual, so an experienced mechanic who is familiar with the steps for a repair can just look up the required torque and test values for the job at hand, and not have to go back to the service manual each time.

 

I`m back to you guys.
From beggining I will tell what i have done again. So I have changed fan clutch, thermostat, coolant(50/50) and both coolant temperture sensors.
But my temperture gauge was working strange, you can see the video how it behaves. So car was running for like 6 min and the temperture gauge showed already 120C, when i shut down the car, the gauge goes up and down, when i turn back the ignition the gauge stays in middle, but when i start the car the gauge goes little above 100C. What you guys think, what is wrong here?
When the gauge showed 120C i checked the motor with thermal image camera and it showed like 82C and the lower coolant pipe was cold and the radiator was cold. And wehn thermostat was open and all cooling system was working full circle, the thermal image on engine showed like 89C.

Here is the video:
W124 E260 Temperture Gauge failure?

So I have feeling that actually my cooling system works fine and temperture is fine, but the temperture gauge i messing with me...

 

EZ enough to verify with a IR temp gun. In addition, I would perform a citric acid flush. These cars shed an average of 10-15C just by performing the citric acid flush.

Everything else after that is going to cost (a lot more)

Mercedes Citrus Flush

 

Good news on the NOT overheating. Just shows that in life you shouldn't always believe what you see or read. Check the facts and check again. Post #2

 

Yea. There is definitely something up with you instrument cluster or its power supply. All of the 3 needles are jumping around rather than rising gently and smoothly as they should.

 

Yes, for next summer I will consider a proper cooling system flush.
I saw that for one wire there was a small damage, I will try to fix it, maybe then my gauge will work better.
Here is the picture of my car, I love Mercedes and my W124 <3