myalias-1234

Less than 3 weeks into our first MB ownership, the "check coolant level" message on the dash appears on our Certified Preowned 2011 E350. No signs of problem driving throughout the day, but the message appeared when we started the car for our trip home - some 30 miles away. The message quickly disappeared and the drive home was uneventful though I monitored the temperature closely on the instrument cluster (the needle went up only slightly above halfway).

When we got home, I checked the manual, and couldn't locate the marker bar in the filler neck to determine if my coolant was low or not. Judging by the attached photo which shows the coolant level below the expansion tank (photo taken while engine was still hot after the 30 mile drive), I'm guessing coolant level is indeed low but wanted to get some input before I head for the dealer.

What I'd also like to know is whether this is just a simple top off, or if there is something else like a leak. Should I be asking for a pressure test of the cooling system? It is certified preowned with 11K miles - I would expect topping off fluids and checking the cooling system to be a part of the CPO certification process. If coolant level was correct at delivery 3 weeks ago, should I be overly concerned?

Car has about 2 years of the new car warranty left, in addition to the 1 yr/100K CPO warranty. Should we expect to pay out of pocket to get something like this looked at and serviced? We purchased the vehicle from an out of state MB dealer, and I'd prefer not to take the car back there with the long drive, so am considering taking it to a local MB dealer.

TIA!

Raymond Lee

I would check it out by taking it to dealer. It is nothing to worry about with the symptom.

ghstudio

It is not normal for a car to lose coolant.....however, if it's a slow loss there is little risk in harming anything. It is, however, important to find the cause of any coolant leak....it could be very minor like a loose connection, or it could be major with a bad head gasket or engine head.

Get it checked out...and I would be very wary if the service tech says "oh, that's normal"

Arrie

As you said it should be part of the CPO process to check all fluid levels. If indeed this was done and you lost the coolant in three weeks to the point of alarm I would be very worried about it.

It is normal to loose some coolant over time. All of this loss should be only thru the breather of the expansion tank, i.e. when coolant temperature raises up and expands and then flows in the expansion tank some of this hot coolant would evaporate out thru the breather. But this is very slow way to loose coolant and if the level was correct at the beginning for sure the level will not go down to the alarm point in three weeks, i.e. if the level was correct when you received the car then you have a more serious issue with it.

Take it in and have them fill it up and then see how it goes. If it does the same again in such a short period of time then you have a real issue like an external leak, which you should see under the car or a bad head gasket that you don't even want to think of...

You could also have the leak at the heater core, which can be difficult to see as the leak most likely comes out with the AC condensate that you always see under car when AC runs and you park. Check this puddle of water for presence of coolant.

thenew3

Just because you bought it 3 weeks ago doesn't mean the CPO checks were done 3 weeks ago. They could've performed the CPO checks months before you bought it.

Also, it could be a faulty coolant level sensor, not necessarily a leak.

Since it's under warranty, just bring it to a dealer and have them check it out.

myalias-1234

Thanks all for the suggestions. Do any of you think the level in the tank looks low (when hot), or can you not tell based on my picture? Either way, I will call tomorrow and have the dealer look into for further investigation.

@thenew3 - Perhaps it is a faulty coolant level sensor - I've driven the car for most of today and so far, the check coolant level message hasn't reappeared again. If the level is indeed low (and the sensor functioning correctly), shouldn't the sensor detect each time the car is started and display the message?

thenew3

A failed or flaky sensor could sometimes report low and other times work fine.

I had one on a BMW before where 2 to 3 days a week it would report coolant low, while the rest of the time it worked fine.

but still, since its under warranty, why not just take it to the dealer and have them check it out? It won't cost anything other than your time to drop off and pick up at the shop.

Arrie

For me it looks kind of low if this picture was taken when the the engine was hot.

And yes, the sensor should report the low level every time the level is low.

Just checked the level in mine and it is only about one inch below the top of the expansion ganister well above the white half of it. And this is cold, car not driven today at all.

myalias-1234

Thanks Arrie. Photo was taken within 10 minutes of a 30 mile drive so engine definitely hot. Looks low to me too yet the sensor hasn't messaged "check coolant level" at all today. My wife told me this evening that she saw the message once on Friday afternoon too, so we know it's been on at least twice.

@thenew3 - I checked the CPO inspection and certification report (which I got a copy of at delivery - thanks in part to your suggestion to my first forum post a few weeks back), and the certification took place in early August 2013 and the "engine compartment/antifreeze protection" line item passed OK, which I assume includes checking the coolant level. Anyway, we'll see what the dealer finds.

Arrie

The dealer will probably just fill it up. You drive it and if it goes down again to the alarm level or to a level that you can see in the white part of the expansion ganister in just a few weeks you have a problem and if you dont see coolant leak under the car or mixed in the AC condensate under the car then it means your engine is getting rid of it. And that is no good news as it almost always means a head gasket problem.

If you look in the expansion ganister the coolant should look clean. If you see kind of "milky" coolant it usually is an indication of a head gasket problem.

Not trying to build a scare here but as you spend a lot of money to get in the MB you need to have this issue diagnosed correctly and repaired correctly.

Bottom line is coolant level should not go down almost at all and for sure not to the alarm point on a car with only 11000 miles on it.

Have them fill it up and see how it is. If the level goes down quick again the dealer should fix it under warranty. If they give you the "this is normal" rant take your car to a tuning shop and ask them to check cylinder pressures. It will cost you some but it will prove if you have a head gasket issue or not.

myalias-1234

@Arrie: The head gasket problem is what scares me from my searches on the forum, and seems to be the worst case scenario. Thanks for taking the time to follow up.

Raymond Lee

If head gasket is blown, you'll see milky gunk in the oil cap. I'll say most likely head gasket is OK.

CEB

C'mon guys. Aren't you all over-reacting a bit.

Nobody knows when the coolant level was last checked. It might have been at CPO or it might not have been checked. At most dealers, the "check" is a visual inspection of any coolant in the expansion tank.

Coolant level goes down with time and temps. If the level was accurately checked when the outside temps were in the 90's and the temp when the low coolant was detected was in the 60's then that could account for it as well.

What the OP needs to do is calm down and top off the fluids - at the dealership if it makes him feel more comfortable. The next morning (cold engine) he should mark the level with a piece of masking tape and monitor the level every few mornings. Small variations based on ambient temps are normal but any major loss will indicate a trip to the dealer for further tests.

Applying the logic used in this thread I should get a brainscan because I worke up this morning with a slight headache.

Arrie

I agree, you need a brain scan.

You obviously did not read any of my posts or if you did you did not understand any of it.

My posts are very clear and simple troubleshooting steps and it does not need negative input from you. Your post did not brin anything new to this topic, only negative critic.

The OP has spend lots of money to get the car he has and sweeping a possible head gasket issue under the rug is not a good thing to do. I think I explained quite well how the coolant level should get down very slowly and there should be no issues if the level was correct three weeks ago at reseiving the car.

Someone needing a logic check is you and not the others who have posted on this topic.

CEB

I realize that you don't like me for some reason (and feel the need to be insulting as well) but I see no reason to even raise issues like head gaskets.

When I bought my S6 in 2002, I got a "low coolant light" about 500 miles after I picked my certified new-to-me car with 3000 miles. I topped it off with a cup of distilled water from a highway rest stop and drove the rest of 600 miles back home.Yes, I kept an eye of the gauges but I never thought of a major issue. I sold the car with 100k miles and never saw that light again - and stuck with the recommended 10k oil change intervals.

Unless the OP knows exactly where the fluid level was when he bought the car, then his first thought should be "it was low when I bought it."

My first step after I buy a car is to check all fluid levels and tire psi. I note that, along with the date, on a sticky and put it in the glove box. If I get any fluid or TPMS errors, I top it off and annotate it on that same paper. If I get an unexpected error thereafter it is time for a visit to the dealer.

What every new owner should do is read the manual and spend some time researching common faults and how cars work in general.

Part of the problem is that we don't teach these things in the US. IIRC, one of the questions on the German driver's license test when I took it 30 some years ago was "What is the normal oil temperature on an engine?"

I certainly don't fault the OP for asking the question but I do fault the responders for suggesting "worst case" scenarios right out the gate.

Arrie

Head gasket is the worst case scenario and the OP obviously was thinking about it already before he posted. You would notice this if you read this thread and think when doing it.

If I was him I would absolutely welcome comments like I have been giving to him. You sound like you are somehow connected to the mighty MB and trying to avoid a customer from making a warranty claim. Are you? (other than obviously being German).

Issue like this with coolant level possibly dropping in very short time can be a very serious issue. Why don't you let THE OP make the decision what he wants to do with HIS CAR and not try to make him feel comfortable about it as he obviously is not. I'm trying to give him info / tools to fight the MB dealer who likely will give him the "this is normal" rant after it happens again. IT IS NOT NORMAL, PERIOD!!!

What comes to the insulting part read your own first post. Your "Applying the logic used in this thread..." is a big insult towards me. I have been giving very professional advice to the OP about his issue and there is absolutely no logic issue with this.

I don't sugarcoat my sentences. I try to give the best knowledge based instruction I have and with this one I know I am 100% correct. Everything I have said is correct and you know what the best part is? When you go thru all this and find out it is not the head gasget you want to go and pop that Champagne bottle and feel good about it.

It is much better this way than living the false thought not having the head gasket issue and then finding out perhaps too late after warranty is over that it was.

Like I posted very early in this thread the first troubleshooting step is to fill the coolant expansion ganister up and drive the car. If it goes down to the alarm level again in just a few weeks then he needs to have it looked at. Also milky coolant or bubbles coming in the tank during engine run would indicate head gasket issues. I think I mentioned this earlier too.

Kaine

There are some of us that are pretty comfortable around our cars and others that are not. Others might feel more comfortable taking the time out of their day to bring it to the stealership.

Either way, do what makes you feel good.

Viewing your pics, it does seem low for a hot engine. Also, don't be all caught up with the CPO label. It all comes down to the quality of workmanship at the dealer. I once test drove a CPO vehicle at Fletcher Jones and when I popped open the hood to check out the engine, we found a ratchet in engine compartment. So, if they're able to leave tools in the engine bay it's not too hard to believe they can't overlook coolant fluid.

If it were me, I probably would've just topped off when engine was cool then monitor it afterwards. If it continues and I was still under warranty, I'd take it in.