Hi all! Unfortunately on my birthday yesterday heading back from dinner , my beloved high mileage w166 did exactly what the title says.
I was driving around 100-110 km/h on the highway last night, and while passing a car I felt a slight hesitation from the engine and then my dash had all lights appear. (I always have an engine light due to swirl flap delete I had half *** without a resistor). I managed to pull off to the shoulder as I couldn’t accelerate anymore. Breaks worked fine and steering wasn’t too bad. Felt a little stiff but not anything crazy. For context my car is a 2014 model with 440,000 kms on it. I got it from its original and only owner at around 290,000 km and it had all service records - only serviced at the dealer. It is in great shape other than it burning / spraying oil (which I top up roughly every 2-3 weeks once I realize it’s low.
I got it towed from the highway back to my property which we have our own shop, I first took my scanner and no new codes were presented to us. Battery voltage was somewhat low, but all electronics, engine fan, and power windows worked. After a bit of scanning we noticed the battery went from 11volts to 7v within an hour. We tried to actuate the starter on our scanner tool and it wouldn’t even engage. I am gonna try to put in a new starter tomorrow from my project GLE350d I’m waiting on body parts for - thankfully I have this around to try certain parts without waiting for them to come in as I need my ML back on the road asap.
We put in the battery from the GLE which is brand new and nothing changed. Electronics light up, and dash - but no crank, however we do hear a slight click from the outside of the car when standing at hood. It is harder to hear from the cabin alone. We ruled out fuses as we checked every fuse in the car - and none seemed to be blown.
The car has a quarter tank of quality diesel, had a new alternator installed only 30,000km ago. We are at a loss for ideas and we are typically very handy and can figure out issues with our cars… we have done the oil cooler seals at 390,000km ourselves… as well as various other repairs or maintenance.
I checked the oil after it got off the flatbed that brought it home, and the oil was actually pretty low. It doesn’t seem like it could be significant though as I have driven it further distances around the same oil reading (just reaching the min mark on dipstick). The strange thing is usually the dash alerts me and gives the oil level low, fill at next refuelling warning. I did not receive that message at all, and the level was as low as when I’ve got the warning once or twice before - as I’m usually good at topping up my oil as I know it consumes it. I opened the oil cap when it first died down and there was no metal shards anywhere, so I hopefully ruled out me blowing the engine. Some smoke came out of oil fill hole when I took off cap, but I’ve seen that smoke when adding oil in the past after it being consumed down close to min. But again I doubt being at minimum on the dip stick would be low enough to cause damage. I could be wrong though… I did not hear any loud noises or really any noise at all, if I had I’d say 100% the engine blew. It has original timing chain as well, so it is a possibility it went but when we inspected it at 390,000km when doing oil cooler seals… it was in very good condition.
I am so lost with this issue, I thought maybe Mercedes has a low oil pressure shut off to try and save the engine if the computer feels it is too low? We haven’t tried to add more oil yet - but I am going to try to top it up to full tonight as well as replace the oil filter and see if it was just shut off due to being low on oil… which again I don’t really think will work as I have driven it many times with it on or close to minimum level.
Tomorrow we are going to attempt to crank the engine manually to see if it will crank - or if it really is blown.

I apologize for the long read, I just want to be as detailed with the information as possible as there could be so many variables to what this issue is. Any and all help would be appreciated - if you have any ideas speculation or thought to what it could be, please share it with me as I could really use the help. Need to get this up and running by the end of Wednesday as I can’t miss work - and transit isn’t an option unfortunately. If I can’t get it sorted I will have to buy a cheap car for the meantime - as my GLE I bought is awaiting its body kit and headlights to be fixed and drive able for me.
If you need any other details to what exactly has happened and what I’ve tried or noticed please feel free to ask. I tried to cover everything but I may have missed some important observations.
Thank you guys in advanced, lots of smart people here so I’m bullish we can solve this!

 

You have a high mileage 450k.Km diesel that died at highway speed -

-- Currently...

1. refuse to crank
2. scanned No faults
3. new starter
4. new battery

-- Now Read status :

1. EIS module live data for "drive authorization"
2. ECU data for starter activity

Do not drain the main battery charge by scanning longtime. Use an external power supply as need.

 

Have you checked for fuel pressure.

 

Yes fuel pressure seems to be fine

 

What exactly are the steps to attempt step 1? (EIS Module) Thanks!

 

you want to check "DRIVE AUTHORIZATION"...

1. connect a power source to battery
2. connect your scanner
3. set IGN to position 1 to stay awake
4. Locate "IGNITION KEY SLOT" Module (EIS)
5. Read its live data
6. Report findings.

 

is there anything specific I should be looking for in the live data?
thanks!

 

Since you have other threads started on the subject, I'll ignore those now and respond here: How much oil comes out of the oil pan drain hole?
Your symptoms describe a sludged up engine to a T. The oil level sensor thinks it is full because it is sludged up. Your engine knows better than that because it was starved for oil and died from lack of lubrication.
Just a guess based on presented evidence here and in your other thread (engine can't be turned over at the crank)

 

Yes, indeed: the status of "DRIVE AUTHORIZATION" and misc other significant data displayed on your chassis.

 

I will check how much oil comes out and report back. We are going to try to remove the serpentine belt and crank by hand as maybe it’s a different seized component on the belt like ac. If it won’t budge I’m sure it seized up:/ Wish me luck!
My main question is would I have necessarily heard a loud noise if it did get starved of oil causing damage? Thanks a lot for the help!

 

A motor starved for oil at highway speed does not simply quit... it throws rods with a proper big-bang finale included.

 

do you believe it being ran at just reaching min level on dip stick is low enough to starve the engine?
I was told previously by my old mechanic that it’s safe as long as I top it off before it’s completely dry on dip stick. Mechanic was probably talking non sense but worth asking!

 

but yes driving at highway speeds I didn’t hear any noises and had no passengers making noise or music playing… very weird that I didn’t experience anything but loss of power and lights coming onto dash

 

Do you do your own oil changes? If so:
when filling the crankcase at the end, were you able to fit the proper amount (8.5 quarts, IIRC) in without it being too full on the dipstick? If the dipstick says that's too much oil, that's a pretty sure sign of sludge buildup in the oil pan - that is, the sludge takes up space that liquid oil should occupy so the fresh oil has nowhere to go but higher on the dipstick.
Side note to that condition: when the low oil light comes on, you've got way less oil that is useable than you think.
Second side note to that condition: When sludge buildup gets excessive, the oil level sensor is covered in sludge and thinks everything is fine.

Hopefully I'm wrong on all counts.

Edited to add: When I got my diesel, I did an oil change and couldn't get the recommended 8.5 quarts in without it being too full. So I did an engine flush treatment, dissolved all the sludge built up in the engine (mind you, that was at around 50,000 miles...) and after dumping everything out the plug I was able to put in 8.5 quarts and the dipstick showed right in the upper half of the "good" zone.
With 400K km on your engine, anything is possible.

 

bottom dipstick mark is 90% chance ok.
2 Quarts less would be bad news.

It sounds like something electrical caused your engine to quit.

Scanner should help chassis survey else it can be a dozen different items like low voltage, drain by driving, loose battery straps....

 

Is this related to the chassis with the defective saddle-tank pump running dry ?

if so then do a good job double checking you fuel supply - No pump like running dry as it gets too hot.

 

yes I do my own oil changes , never noticed it being over when filling the recommended amount. I haven’t had the pan off in a long time , only at 370k when I had to change the gasket. But back then there was no sludge
however the past while I’ve been going 4000km over the 10,000km oil change interval due to having to add like 8L of oil a month to keep up with the oil loss.
im sure at this point the engine is 100% seized though sadly as we took off serpentine pulley and tried to crank the engine by hand again. Still no budge