2010 GL550 135k miles I took the GL on a 2 hour round trip but prior to leaving I took the GL to Autozone and they load tested the battery, alternator, and starter. Everything checked out just fine. I then took it to my local MB dealership to have the recall checked and have an alignment done. My GL wasn't affected by the recall. My S.A. then called and stated they couldnt preform the alignment because my steering rack was shot. The tech came into the office and stated the bushings were shot on the rack and it had a small leak. I still took the GL on the trip. I got to my destination (an hour there) and the "SHUT OFF VEHICLE ENGINE TEMP TOO HOT" light clicked on. I parked and went into to the wedding i was attending. Before departure back home I looked under the GL and didn't see any puddles.

I stated the GL and about 12 miles down the road the GL began to over heat. I pulled over and let it cool down. I eventually made it to a gas station and shut the GL off.

Sat at the gas station for maybe 30 mins, attempted to turn on the GL and it wouldn't crank. The dashboard illuminated with all the lights and I kept getting the tick, tick when attempting to start.

I then noticed a puddle of leaking antifreeze under the GL. Left it over night and had someone pick me up.

Called a tow truck today and just picked it up. The tow operator hooked up a jump pack and it started right up.

My question is, could it have been possible that both the battery AND coolant both went at the same time or is it something my dealership might have done.

Note: I had a full coolant flush 2 years ago at my local MB dealership and had a new battery installed in 2017.

Tomorrow I'm going to get under the GL and attempt to locate the coolant leak, but again, everything was fine prior to taking it to my local dealership.

 

Until you determine the cause of both problems, its a guess. I don't believe that MB stealerships would wilfully damage your car as a business policy. They're making enough out of us all anyway. Let everyone know what the cause of the issues are.

 

Thermostat failure is more likely than a leak, which would have popped up an indicator for low coolant.

You could easily have multiple concurrent problems. Never constrain yourself to looking for a single causal factor.

 

Edit: Why can't I delete a duplicate post?

 

@eric_in_sd I'm glad you replied. I know you did extensive research on the best battery to buy for the GL. I'm aware it needs to be an AGM, but what was your final conclusion? I tried to locate your thread but was unsuccessful. I will say I'm not replacing the steering rack. The master tech at MB said I have a minor leak on the rack but it's the bushings that are shot. I've seen several threads here stating it's not that difficult of a job. I cannot locate my coolant leak, yet. More searching today. ​​​​​​​​​​​​​​I did note when I turned off my GL I could hear air bubbles which I thought may have been in the coolant system but never had any issues until I was Roadside. Eric- since you used to live in St Louis, my tow bill wasn't bad, from New Haven MO to St Louis MO was only $200. It's an 2 hour round trip.

 

I concluded the following reasons for favoring AGM:
1) The increased lifetime more than offsets the higher cost.
2) The front SAM is in the well along with the battery; you definitely don't want sulfuric acid fumes around electronics.
3) In case of rollover, you don't want battery acid dripping on your hapless front row passengers, or you.

Keep on top of alternator and starter health, and keep a battery maintainer when garaged for more than a day or so, and the battery will last a nice long time.

If you don't have low coolant in the reservoir, you don't have a leak. My money is on your thermostat having gone bad.

 

 

Coolant tank was bone dry and I had a steady stream before the battery died.

I'm aware the power steering reservoir leaks extremely bad. I actually filled the power steering reservoir up prior to leaving for my trip. But that would not cause my vehicle to over heat.

I can't find where the coolant leak is coming from.

I did note when it was over heating I pinched the upper radiator hose and there was no pressure in the system.

 

When it first overheated, that was a sign that something was wrong and you should have checked the coolant level at that time. You'll only get a puddle if the coolant level is above the leak spot once you shut 'er down. Once it started overheating, you should not have tried to drive any further without checking things out.

Fill it back up and look for the leak.

or

Pressure test the coolant system and look/listen for the leak.

The battery and coolant... I'm not sure how they would be related. Check battery connections for clean and tight as a starting point. Check the resting voltage of the battery and the charging voltage (after the cooling system is filled, of course).

 

When it first over heated I pulled over Roadside and let it cool down enough to drive 2 miles to a gas station. I was on a dark country road.

When I did check it, it was indeed empty.

The battery compartment is dry and I see no signs of water intrusion

 

Jus to keep things straight to help with diagnosis... that was the second time it overheated.

Please re-read my post about the battery - I wasn't referring to the compartment being wet or dry in any way.

 

Jeez dude, you're all over the place. One thing at a time.

You have a coolant leak; refill with plain water and find where it is leaking from. When you drain it later, replace with coolant. Forget about the battery and power steering right now. By far this is the critical issue to be dealing with.

This is why I want to get an android head unit. The dash temperature gauge is useless. Mine reads 90C when I know the tstat starts to open at 100C and Torque tells me the engine computer agrees.

 

I have an old '97 BMW and the dash gauge is even more useless. I actually found out there is a 50*F buffer built into it before it starts to swing off "normal"! I watched my plug-in scanner report exact temps as I watched the dash gauge needle. Now, in my '98 Suburban -- diesel, if it matters -- the needle responds to the exact temp in real time. I suppose the luxury car thinking is that they don't want customers coming in to complain that something's wrong since the needle doesn't stay right in the middle!

 

Yeah, it's weird. I would think the German obsession with precision would rule this out, but no. Americans are oddly more pragmatic about it; they'll have a tractor-like set of gauges, but dammit, they work.

The other is the inanity of the trip computer switching over to a cartoon of a car at a filling station when the tank drops down to a gallon or so. At the most critical time, it stops giving information.

 

Dennis- Yes, that was the second time it overheated. My error I was reading rather quickly and must have looked over your response. Eric- I was trying to keep/reuse as much coolant as I possibly could due to having the full coolant flush a couple years ago from the dealership but I suppose I'll have to purchase all new due to the fact I'm unable to locate the leak. I have a feeling it's coming from my radiator. Upon further inspection of the battery well I observed the following. Unable to tell exactly what the fluid is so here's a few photos... ​​​​​​​



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Yup, I can't tell what that fluid is in the compartment, but it looks dried up so not really worried about it. If it's coolant, though, that means bigger issues as your heater core is likely leaking. Maybe it's battery acid... maybe it's a leftover cleaning solution that's dried up? Hard to say. But again, that's not important right now.

What about what I asked about in Post #9? I think this is the last time I'll ask that question - you're wearing my finger tips out

 

I am fresh off of struggling with coolant leaks, so hopefully I can be of some assistance.

If you haven't already, take off the belly pan. Even so, it can be difficult to discern the leak source, if coming from around the radiator, as the radiator is on top of a flat horizontal cross beam that allows fluid to run from one side to the other.

If the power steering return hoses, which go to the radiator, leak, the power steering fluid may drip onto the lateral heater hose that runs beneath the radiator, which will then leak. This can be replaced with 3/4" heater hose at considerable savings versus the OEM shaped hose. If when you inspect this hose, the section on the driver's side, you find it is mushy, greasy, or funny looking, there is one likely culprit.

The radiator may have started leaking from the side tanks.

The coolant expansion tank and its cap can also leak.

Don't worry about the cost of the coolant. It is trivial compared to the parts you will likely be replacing, let alone the potential damage from overheating the motor.

Do you have a history of needing to top up coolant? Did you get a coolant low error message before the overheat error message? If not, then I go back to thinking your thermostat failed in the shut position - and the reason your coolant is gone is because it boiled off.

 

Dennis- my apologies again. I did fill the reservoir tank back up and looked for leaks. I thought I observed a few drips coming from the upper radiator hose where it connects to the actual radiator, but couldn't be confident. I haven't checked any voltage yet due to trying to sort out the leak first. Eric- I think you're on to something. The antifreeze leak is coming from the drivers side and my power steering fluid is leaking bad. I've had an intermittent "top off coolant" light but most of the time when I cold check it its at the proper level. I just took these photos under the power steering reservoir which is soaked but I can't pinpoint what exact fluid it is. ​​​​​​​​​​​​​​​​​​​​​

 

Fill with water, start idling, top up the water as necessary after air is burped out, cap the reservoir, wait for it to start leaking, observe source.

Depending on the miles you have on this thing, I would plan on replacing: radiator, thermostat, upper radiator hose, lower radiator hose, lower heater hose, power steering return lines (one is custom, one can use ordinary fuel hose), power steering reservoir, and o-ring type seal where reservoir mounts to pump, coolant reservoir, reservoir cap.

The main reason I would replace the radiator is because of the o-rings where the power steering fluid heat exchanger goes into the driver side tank, and where the transmission fluid heat exhanger does likewise on the passenger side. Also there are giant o-rings between the side tanks and the aluminum fins, but I would bet those take forever and a day to fail.

You could hold off on the coolant reservoir and cap if you can confirm they are not leaking. But if you have to top up coolant occasionally, there is a decent chance one or both is leaking. Mine started leaking where the upper (small) return tube goes to the radiator, and the cap started leaking shortly thereafter.

While you have the power steering reservoir off, change the exhaust cam magnet to new type if it is not already.

It is intimidating to do all these things at once, and it increases the odds that a repair will have some glitch while you are in there, but trust me, these things are all physically in each other's way and the labor savings will be yuge.

 

If it's leaking as quickly as it seems like, I think you'll find the leak pretty readily once you fill back up. It may or may not do it till it reaches operating temp, though, so be patient. Or just pressurize the system as I noted above - it's sometimes easier because you can get a better look at things while the engine is off (safer, too).

 

perhaps look at life po4 lithium, which i done thrilled to bits with it.

 

Thanks for all the replies. The GL has been sitting as I've been out of town. I will report back when I figure all this out.

Note: My GL550 has 138xxx miles on it.

 

UPDATE I used a jump pack to start the GL. As soon as I started it the cooling fan went into automatic highest (fastest) setting on a cold start. I added coolant and waited for it to reach operating temperature.

The cooling fan stayed on high the entire time.

Just below the upper radiator hose it appears there's a power steering hose that connects to the radiator and it appears that's what's leaking. I took the following photos.

 

Is your PS fluid the green LiquiMoly mineraloel stuff or is that prestone green coolant seen there?

 

I poured in the green pristine antifreeze and I also use CHF 11 power steering fluid.