To start off, I am a complete newbie to MB. To make the long story short, I recently purchased a 2011 E350 wagon for DD duties. Against my better judgment, I picked up a rebuilt car because I got frustrated with a long search. Yesterday I was on a ferry and let the car idling. I left the car for about 10 minutes and when I came back, the low coolant warning was on and the temp needle was at 120. I immediately shut off the car, but there were no other signs of overheating and the coolant level was correct in the reservoir. After I restarted the car to get off the ferry (about 5 minutes later), the warning light was gone and the temp was normal. I continued to drive for another 5 minutes and the coolant warning light came back on. The needle went from normal to 120 instantaneously. This time around I let the car cool off for a bit longer and started driving again. I continued to drive the car all day yesterday and today without any issues. I should also mention that this morning the coolant level was normal and there was no pressure in the upper rad hose. What could this possibly be? I searched already, but couldn't find a similar scenario. If the car legitimately overheated, there is no way the temp would go down to normal within 5 minutes after shutting off the engine. I also find it suspicious that it would go from normal to 120 in an instant.

 

I'd start by testing the gauge.

 

Regarding the sudden jump from normal to 120 on the cluster temperature gauge, the following is a good read

https://mbworld.org/forums/e-class-w...inda-liar.html

On the overheating when idling, and the temperature not going down when the engine I would check
1 - does the radiator fan run when you shut the engine off and/or when the cluster says it is overheating, or even at normal?
2 - did you have the AC on? was the radiator fan running while the AC was on?
3 - If the fan was not running, I would try to check for codes. I do not recall if there is a separate relay or built-in into the fan regulator.
4 - Perhaps a faulty radiator/reservoir cap? Get it tested for the correct relief pressure.

My 2c

 

KISS.

Pull codes. Replace ECTS.

Among other things, but that's my 2c, and where I'd start. With a rebuilt title, anything is possible.

 

1. The radiator fan was not running when the car was supposedly overheating. It does work however.
2. Yes to both.
3. What's a good scanner for these cars? I have software for my laptop that I use with my BMWs via an OBD cable.
4. I will check, but I did not observe any air venting. There was no evidence of any coolant leaks either (or smell for that matter)

 

Do you have any software/device recommendations? And yes, I am discovering a number of shoddy repairs already. I did buy the car for the right price and I do expect it to be somewhat of a project.

 

And the temp sensor...

 

I am a newbie regarding working on MB, so I may not have made the best decisions. So far, I bought the iCarsoft EU Pro so I could scan the European cars I had access to: 1 BMW and 4 MB (only 1 is mine though). The BMW was sold a few months back, so MB only now. However, I am planning to follow

https://mbworld.org/forums/e-class-w...u-version.html

and learn from there. Since you are already working from the laptop to the BMW, that is probably a similar workflow for you with minimal investment ($$) up front. It may require a bit of software setup and installation debugging though.

A separate thread with overheating issues on a 2013 W212 E350 is worth reading (some documentation as well)

https://mbworld.org/forums/e-class-w...erheating.html

 

Yep, understood.

iCarsoft is a fan favorite here

 

Been a week, we need an update.

 

Haven't gotten around to it, but I will report back when I find the culprit. I'm currently dealing with some transmission issues in my E90 M3 and some jackwagon hit my Z3M in a parking lot. When it rains it pours I guess!

 

Sorry to bump an older thread, but I have been driving the car almost daily since this issue first occurred and it never happened again. I thoroughly inspected the hoses and found some minor seepage from the rubber hose that runs from the expansion tank to the radiator. I replaced this hose and used this opportunity to flush the coolant. I noticed that the old coolant was generic green, so I replaced it with Mercedes blue.

 

I would just have your fan checked, because to me it looks like the culprit.

 

That was my initial thought, but I still don't think that the car truly overheated. The coolant was never low and the rapid movement of the temp needle also didn't seem right.

 

The dash gauge is dummy gauge and will not show temperature changes till they become critical.
I drive my MB with ScanGauge, mainly for diesel emission system monitoring, but I observe temperature as well.
When dash gauge is glued to 90C, the ScanGauge shows 78-85C variations on colder (80F) days.
I would double and triple check the coolant level. From your description you might have " hot spots" phenomena, where steam pockets will raise coolant level, but then will drop down after cooling.
And as concluded, engine staying cool at cruising, but overheating on idle is indication of cooling fans malfunction.
Green coolant is no-no on MB, although mix of old, pee colored coolant and new, blue one will result in greenish color.

 

One of our long time members had an Icarsoft MB2 for sale about a week ago, maybe contact "LilBenz" for availability and price?