Ntuck

I have been on vacation for 2 weeks and drove my GL 10 hours to get to my destination. Almost every day since I've been here I've had a warning light pop up on the dash saying, "Check coolant levels." So the first day I panicked thinking the thing was low and ran out to buy some antifreeze. Get home, open the hood and check the level and it's almost full. I also then read that you have to add special MB coolant anyway. Does me no good even if I needed to add it because I'm on Nantucket, MA and there are no MB dealerships! Plus the car is 11 months old and never heard of one running out so fast. So anyway, was wondering if anyone else has had this light come on before and had the level at a normal range? I will be taking it in next week once I get home for an oil change and will ask them too but just thought I would ask since I'm out of town. It's a Diesel too if that matters.

Thanks!

JimBarnhart

I've never seen the coolant light come on, either in my X164 or X166. Sounds to me like a faulty sensor if it's full when you check it.

Ntuck

Thanks Jim! Could be...hopefully they can fix it.

Missykins

Nice ride, dude.



The same thing has happened to me with my C320 4MATIC wagon--light comes on, coolant within correct amount.

Have you checked your windshield washer fluid level lately? I swear to God--once I refilled the wiper fluid reservoir I no longer had check coolant issues again--the sensors must be linked somehow.

methos1969

Mine comes on every couple thousand miles. In only add about a half inch to top it off and lights goes out for a few months.

ogre.

I can't resist chuckling at the car suggesting: 'check coolant levels'.

You checked it, as instructed, all ok. I can imagine that car responding: 'I never said the coolant level was low.'

cyberorth

You are just fine adding a bit distiller water as mb dealers often do. My GL did that shortly after delivery. It seamed a bit coolant had splashed on the underside of hood from predelivery. I talked to my mb dealer and they recommended adding distiller water. 8k miles later and the coolant is fine. I was told by the as that x166 has a very sensitive coolant sensor and slight fluctuation sets it off.

Ntuck

Dealer fixed it. Must have been some weird sensor issue. Thanks for the replies!

a3grimlock

The position of the vehicle can trigger the coolant level if you are driving in a hillside, I have this message too when I'm driving coming from the beach towards the mountain area. Just in case you do have a low coolant level and want to be safe, using a distilled water are better than using a wrong type of fluid. Just make sure top off with MB star coolant once you get home.

cyclrder

Car sat out overnight in20s temp....My coolant warning came on on startup.... 4k on the odometer.... I have noticed chalky water spots in the engine bay.

Checked coolant and maybe it is down 1/4 inch.... After checking... The light went out.

Adding to my list.....

awiner

Are you guys also adding coolant to the auxiliary turbo cooling reservoir under the engine cover ?

43221B

That isn't the issue. A top off of the main reservoir turns the light off. My light came on with about the same mileage as cyclrder's. I don't have any leaks but I can barely smell antifreeze after pulling into my garage when the engine is hot which makes me think there is a small air leak that is slowly letting some evaporation take place. Not a big deal as long as it doesn't get worse. I added about a cup of pink antifreeze/distilled water and I've been watching the level. If it is evaporating, it is doing it very slowly because I haven't seen a change in about 4 weeks.

awiner

I understand that, but I have seen more than a few X166 (GL550) models with low auxiliary reservoirs. Most owners have no idea that a second coolant reservoir even exists under the engine cowling.

cyclrder

I haven't noticed a second reservoir and I have even replaced my air filters requiring removal of the upper engine facade.

I too have smelled the traces of antifreeze...... But the chalky residue on the left side of the top engine bays makes me wonder.....

clueless newbie

We bought a GL350 BlueTec in late September. We arrived in NH yesterday and and parked outside overnight (so, cold). I came out this morning and the Check Coolant Level light is on. I checked, and if I am reading the right thing as the indicator, it is maybe two inches below that level. There is no dealership anywhere near here and since it's New Year's Day, auto parts stores are closed. I freely admit I know nothing about cars and have no idea whether this car can be driven without hurting the engine. Should I add some distilled water, as described earlier in this thread? I can't get MB-approved coolant before driving back to MA and don't know how to find out whether other brands are ok (I've googled and not found anything that seems like a reliable source.) Is this not actually a big deal? Why would I need to add coolant when the car is only a few months old? I haven't seen any puddles or evidence of leaks in the garage. Thanks!

cadetdrivr

Don't worry about it---you are just barely low enough to trigger the sensor and the system is quite sensitive, IMHO. I'd still keep an eye on to insure there are not drastic level changes, but at the current level you are fine.

Stop at the next MB dealer and have them add a bit when you have a chance in the next few weeks.

43221B

Agree, you are fine. They are filling the reservoir too low at the factory for some reason. If you have to, add distilled water, but be aware that you start lowering the boiling temp if you just add water without antifreeze.

blittle

Perfect advice....been there and done that ...as they say!