Trerivers

Engine Compartment
Where is the Coolant Temperature Sensor on my 2009 ML 350? Please attach any link(video or otherwise) that may help in its replacement. I am a DIYer.

MJ50

moved to W164 forum...

Maj. Dundee

At the rear of the engine.

Trerivers

Found it, removed it, and replaced it. However, after install with new o-ring, part does not seem to fit as snug as the part I removed. Part numbers match(though it is aftermarket), and it also passed the eye test. Kind of afraid to top of fluid and start up. Don't want to cause another issue. Any insights?

Maj. Dundee

Aftermarket is the key word. Buy one from a dealer.

tmryan

Did you have any issues removing the sensor. any tips appreciated

Maj. Dundee

It's one screw, what could be the problem.

tmryan

Sound like it's no big deal. Always appreciate input from those who have done the task. Don't know--if you don't ask.

Thanks for the input.

Maj. Dundee

What year and model, gas or diesel is your veh., Ill give you the instructions?

tmryan

2010 E350 4matic

Maj. Dundee

You are on the wrong forum but here is the location.

Harinderassie

Hey Maj. Dundee can you help me i am looking for a coolant temperature sensor for a 2012 Mercedes Benz GL350 Bluetec. Also the circuit diagram for the radiator fan module to the ECM. As my car is overheating and the cooling fan doe snot move.

Maj. Dundee

The following diagram is for W164 CDI as I cannot gain access to X166 diagram, but it should be the same. Do not apply voltage to any line as you may toast the ECM.

Check fuse #7 100 amp at the Front Pre-Fuse Box for the fan M4/7, to see if it is blown.

Here is the diagram and legend.

Harinderassie

Thank You Maj. Dundee just wondering do you have a more clear WHIP (R) printout. IT is hard to make out the writing on the blackground paper.

Maj. Dundee

When it opens up it will be black, just scroll down.

Harinderassie

Sorry to bother you, but can you show me in a picture where this fuse is located that is outlined below sir

Check fuse #7 100 amp at the Front Pre-Fuse Box for the fan M4/7, to see if it is blown.

Maj. Dundee

There are probably two fuse boxes under the hood, one large and one small (Pre-Fuse Box).

Maj. Dundee

Do you have this under your hood?

Harinderassie

Ok after a lot of reading and testing we found out it is the fan module that is shot. ECM has good power going intot he unit. I guess i will be looking for a complete fan.

Maj. Dundee

Very expensive new.

Harinderassie

Thanks i have full power there.

Harinderassie

We took the radiator fan out and noticed that the outer bearing is broken and it would not move, we have removed the bearing and it moves freely. Now i just have to figure out what type of bearing this is an di might be good a few hundred dollars if i do not have to get the whole fan unit.

Maj. Dundee

A new fan from M/B is approx. $600.

If you get a used one or buy an aftermarket one, you might have the same prob. in 6 months. Choose wisely.

Liro

Hi Maj,
I have a ML 350 Bluetec of 2010, and on idle very ofter the RPM's stays at 800, but usually it should be at 700 RPM. I dont get any code at all and very difficult to know whats going on. Have you seen something similar from your experience? Could the coolant temp sensor intermittent signal cause that?

Maj. Dundee

Yes it could, BUT you should have a code # to back it up. Do you have a scanner type reader to scan all modules?.

Look at the PDF and see all the possibilities that could be the cause