donaldt

So my 09 sedan has just gave me a coolant low warning at just 30000km
Is it common or is it a heads up for headbolts problem

How exactly should I check

Thanks

Roswell

Just top it off & keep an eye on it.

If no white smoke coming from exhaust, I would say u are ok.

whoover

Check your oil dipstick for the presence of water. The coolant system is sealed so it's not trivial. I'd take it in to be checked and topped up. You have to use the right coolant, mixed 50-50 with water, preferably distilled.

abcut973

Yep check your level after topping up.
Check for leaks around the master cylinder or underneath your car for spots.
No need to panic trouble shoot step by step before jumping into conclusions.

Merc63

Preferably distiller water, master cylinder, white smoke from exhaust?

Hmmm

Could be nothing, could be a stretched or broken head bolt.

If you have warranty take it to the dealer, have them pressure test the cooling system. Record that you were in there with a low coolant message... Worst case and have them top it up.

Say you know that you are aware of the head bolt issue and would like it checked out. Your coolant system shouldn't be loosing fluid.

donaldt

Yea been driving for a long time it don't think I have ever had any coolant issues
Thing is this car is out of warranty
Will top it up with distiller water later and keep an eye on it

Might go get it checked later this week

Thanks for the advices

whoover

Not a great idea to top up with pure water. The 50-50 mix needs to be maintained to within a percent or two. You really want to get some of the right coolant at the dealer and mix it 50-50.

EC C63

Recommend following Merc63's advice. Nothing replaces the assurance of a pressure test performed by a Merc dealer, have it documented, and lastly have them top it off. Documenting the service visit may be useful to you later.

Ingenieur

Is this the first time in 5 or 6 years?
The car only has 18k miles?
Have you ever checked the level before?

Top it off per manual
Car should be cold (setting over night on a level spot)
It can be checked warm but cold is better imo
Use a flashlight to see better
In the tank you will see a 1/2 white and 1/2 black 'tab'
Adjust the level EXACTLY to the black/white transition
After you do that check it weekly in the same manner
Cold, same spot, etc
If checked hot it should be 15 mm higher
But do it cold to have a more consistent basis for comparison

Don't panic all cars use coolant
That is why the manual says to check/top off

donaldt

Yes wouldn't be as panicky if there were no headbolt problems
Anyway looked into the coolant tank it's really just slightly down
Filled about half a bottle of mobile one coolant then another half a bottle of redline water wetter and it was already full
Was gonna finish the whole bottle of water wetter and add water if needed
Will check again in a few days but yes never really had to fill coolant in over 10 years of driving
I must be lucky

Ingenieur

How many ounces/ml total?
The tank is only about 1/2 full correct, ie, at the middle of the tab

Merc63

Slightly down on a closed system...

Get a pressure test. But I wonder if a pressure test would show a slightly stretched bolt. Engine would need to be running to create enough pressure for the leak.

donaldt

Damn
Should it be only half full lol
First top off ever
Any idea on how to drain it now
I sound like a first time car owner

Ingenieur

Yes
About 1/2 full
There is a tab or level marker at the joint where the black/white halfs are joined
You need a squeeze bulb and remove some

Ingenieur

Again, some loss is normal since NO system is perfect
The caps leak abit
Hoses weep
Joints seep
Etc

If you lost 1 oz per year for 6 years no issue
If you lost 6 oz in a week there is an issue

Look in your manual index 'coolant check level'
It says to check and ADD if required

The system holds 400 oz
If I lost 1 or 2 % 4 or 8 oz over 6 years and 500 hours of operation I would not consider that an issue

http://www4.mercedes-benz.com/manual...30_2389_31.jpg

Level must be below the small hose entering the front of the tank

How much did you add?
It may be the sensor

donaldt

We'll I didn't top it off to a point it spills I mean I know it heats up and expands hahahahahaha
Will check again when it's cold tomorrow

So it should be just above the clear part of the bottle right

whoover

What is Mobile 1 coolant? The correct coolant is Zerex G-05. It's a fairly different chemistry from most and is designed for the metals of our cooling system and to work with the silica gel packet in that overflow container. If you've used an incompatible coolant, you should probably get the coolant changed at some point before long.

BTW, the level sensors sometimes fail and give false alerts.

Ingenieur

Look in your manual
How much did you add
Driving the car over-filled will make it run hotter

Haven't you read anything?
There is a fill level marker IN the tank
http://www4.mercedes-benz.com/manual...30_2389_31.jpg

Ingenieur

Mobil makes a MB 325.0 spec coolant

donaldt

If this is the case I believe it might have been a sensor fault
When I filled the coolant the overfill bottle actually had fluid inside
I think probably less than a liter of coolant was added

I thought mobile one was safe

Damn it I sound like a noob(ok I am one)

Ingenieur

You added less than a liter and it filled it basically to the top?
Yep guessing you weren't actually low
Adjust to the proper level
If you do this before running the car you will remove 1/2 of what you put in

The coolant bottle should have specs on it
Look for MB 325.0
Was it dark blue/green?

whoover

The approved coolant list:
http://bevo.mercedes-benz.com/bevolisten/325.0_en.html

Yes, there is a Mobil product on the list, but I've never seen it for sale. The only one that my local parts place carries is the Zerex G-05. Just advising being careful.

whoover

The good news is that coolant level sensor failures are much more common than head bolt failures.

And the technology in these cars is pretty advanced, so minor screw-ups like this are understandable if you're used to normal cars.

If the coolant wasn't the specific approved Mobil GS 333, have the system flushed with the right stuff to avoid expensive problems like water pump leaks or radiator failures in the future. Then you'll be good for 150,000 miles.