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My 2010 ML 350 blutec refuses to start when it gets below zero overnight. My block does not have the factory bung for the block heater, that was my first hope. I installed an oil pan heater, that throws a CEL and is only moderately helpful with starting in the morning. I have also tried a new battery and adding more anti-gel than comes from the pump (it's required by law here). The dang thing just won't start without a long struggle of about 10-15 glow plug & cranking cycles.
Is there a tank heater that can be put in line with the lower radiator hose?
Also, make darn sure that all of your glow plugs are working well.
I have been thinking about how to heat the coolant. I really don't want to cut into a hose and so far that is the only method I have found. I came across a freeze plug heater that says it fits, but I can't confirm and it looks questionable.
Yes, all glow plugs are fine. I had a Mercedes mechanic look over the car and told him to fix everything.
Update!! -16°F right now and it started. I had the oil pan heater auto turn on at 3am so it was on for 4 hours when I went to start. Oil temp was 25°F so no worry about burning. Bad news, it threw a CEL code saying the oil temp was higher than the water temp. I hope that is one that will clear itself after time. The local parts shop dosen't clear codes anymore (O'Riley's).
Glad it started!
As far as codes go, that is one of the absolutely necessary tools for all owners of mercedes... well, really ANY car... that is more than warranty years old. A decent one is cheaper than your time to drive to the auto parts store to get the code read.
A CDI diesel should be able to start well into the single digits without any glow plugs. It may take a few seconds of cranking, it may smoke like a campfire for a minute, but it should start.
I'd check compression and fuel pressure.
Last edited by rapidoxidation; Dec 1, 2024 at 10:03 AM.
Glad it started!
As far as codes go, that is one of the absolutely necessary tools for all owners of mercedes... well, really ANY car... that is more than warranty years old. A decent one is cheaper than your time to drive to the auto parts store to get the code read.
A CDI diesel should be able to start well into the single digits without any glow plugs. It may take a few seconds of cranking, it may smoke like a campfire for a minute, but it should start.
I'd check compression and fuel pressure.
Yeah, I need to get an OBD tool. I am just overwhelmed with all of the options and garbage that is difficult to weed through. Been lazy since O'Riley's is right here and they used to lend out a pretty decent code reader. I am thinking about getting a basic one today, just to read and clear standard codes. The extra MB codes make the costs and choices unbearable to pick; I don't have the $500 to buy the fancy ones.
Mine starts just fine in the single digits, it gets rough at about 0 and below -5F it takes multiple starts; yesterday took 10 starts. It has that auto crank thing, so it quits cranking after about 10 seconds on its own. The biggest issue is when it gets really cold overnight, -22 two nights ago and -11 last night. I have the heater setup to only be on for the coldest hours of the night, but I go to work early enough that it is still in the negatives when I have to leave for work.
For diesels I strongly advise monitoring scanner, like ScanGauge to observe mainly DPF regeneration, but you can monitor everything with it.
The advanced SG3 can be had for about $240, when older SG2 are much cheaper, but also much harder to operate.
With hard start, I would start with basics.
-new air filter
-new fuel filter.
Monitoring scanner will tell you fuel pressures, what would point you in right direction.
For diesels I strongly advise monitoring scanner, like ScanGauge to observe mainly DPF regeneration, but you can monitor everything with it.
The advanced SG3 can be had for about $240, when older SG2 are much cheaper, but also much harder to operate.
With hard start, I would start with basics.
-new air filter
-new fuel filter.
Monitoring scanner will tell you fuel pressures, what would point you in right direction.
Its only hard start around below -5*F overnight. I bought my MB last year and replaced every filter and fluid at the 150K mile mark about a month after purchase. Only used OEM and all work was done by an MB mechanic. That mechanic is out of ideas about the hard start other than "it's too cold" where I live... I move in two weeks so that should help the problem...lol!
I just bought a scanner that is specifically for German automobiles called a
. It has all of the features everyone says it needs and the reviews specifically say they had success on DPF and DEF system work. Thank you both for pressing me enough to finally pull the trigger after over a year of poaching (>.<). Hopefully the cold snap will go away and when the scanner comes on Thursday I can clear the code and put the heater away anyhow.
Current temp is -5*F at noon, car has been starting good all morning.
I guess its just a cold AF issue like the mechanic says! Unless you all have other ideas?
Glow plugs would be most likely culprit (or glow plug relay), or your fuel is not flowing properly, like the fuel station did not put in winterized fuel. There are plenty of YouTube videos of these cars starting well below zero with no oil pan or coolant preheating.
If your coolant temperature sensor thinks it is warmer than it actually is, the glow plug relay won't stay on as long as it should thus resulting in hard starts at cold temps.
A decent scanner will tell you what the sensor thinks the coolant temperature is. You can compare what it thinks to what the actual coolant temp is and go from there.
Glow plugs would be most likely culprit (or glow plug relay), or your fuel is not flowing properly, like the fuel station did not put in winterized fuel. There are plenty of YouTube videos of these cars starting well below zero with no oil pan or coolant preheating.
That guy starts at the same temp I have been having issues with. I have not tried multiple glow plug warm ups though. Will give that a shot when I don't need to go somewhere, just in case
I am curious if his temperature report was extended or just a dip in the temp. Mine was at over 24 hours below zero F without attempting to start.
Oh!!! And he seems to be not in the US, so can probably get #1 diesel, which starts better at low temps.
If your coolant temp sensor is acting up, I seem to recall that unplugging the sensor (just have to find which plug!) will make the ECU think it is as cold as it ever can get and will activate the glow plug relay accordingly.
Might be worth a quick try, if you can find the right sensor to unplug.
Also: Always always ALWAYS add a diesel fuel additive to each and every tank of fuel. Personally, I've been using Power Service in the gray bottle since about 2001 and have literally had zero fuel related problems in 3 chevy trucks ('96 6.5L, '03 and '05 6.6L duramax and 3 benz diesels ('85 300D, 2005 E320 CDI, and my current ML350) when I use the additive. Two years ago, I neglected to add it to a couple sequential fillups in my '05 Duramax during a cold week of way sub-zero (like reliably 20 to 30 below) and paid the price via a waxed filter. The truck would start fine, but any real demand for fuel, even after warmed up, and the engine would be starved for fuel. Sure, the fuel stations should have winter diesel with the juice already added... but I like to roll my own in addition. A half gallon bottle of Power Service lives in my Chevy and my ML350 year round, with about a cup (8oz.) added with each and every fill up.
The '05 Duramax has 330K miles on it and starts like it is new. Injectors haven't been touched since I got the truck with 130K on it; can't say what happened before that. ML has just over 80K, owned since 50K.
Last edited by rapidoxidation; Dec 1, 2024 at 08:28 PM.
That guy starts at the same temp I have been having issues with. I have not tried multiple glow plug warm ups though. Will give that a shot when I don't need to go somewhere, just in case
I am curious if his temperature report was extended or just a dip in the temp. Mine was at over 24 hours below zero F without attempting to start.
Oh!!! And he seems to be not in the US, so can probably get #1 diesel, which starts better at low temps.
In the US you still get blends and what not even though listed as #2. It prevents jelling. More modern diesels will start at very low temps without issue, not like the oldies where if they werent plugged in you may as well forget it. I think the coldest Ive started my cummins was -15F, not plugged in and the intake heater (version of glow plug) is disconnected. Sounded rough and smoked but fired right up. A 2010 should start regardless, seems to be something slight under the radar that needs finding.
The only time mine didn't start, it was about 15F and it had been outside all night. It sounded like all was well cranking wise, but there was no sign of fire. No smoke and no popping. I called AAA, expecting I'd need to have it towed somewhere warm, but he put a jump box on it and it fired right up. I replaced the battery and haven't had an issue since. Thinking back, no smoke should have told me that it wasn't injecting any fuel. My guess is it was not quite reaching minimum cranking speed and the injectors were not being activated.
I've never needed any additives to prevent jelling, except one time in the tractor, when I tried to start it in sub-freezing temperatures on fuel I probably bought in August.
The factory block heater is an inline unit.
Under normal operating conditions, since the oil cooler is water cooled, oil temp higher than coolant would be a sign of a big problem. I'm sure the code will clear on its own.
My TOPDON EU vehicle specific scan tool came in yesterday. I cleared all the codes and drove it around today. Then read the codes again. There were two: passenger courtesy light is out and this one below. Scan tool findings
I looked into it with the tool a bit and got scared with the number of things the tool does. Decided I would ask you all if you know what that means. It is part of the ECM scan. Thoughts?
If you don't have an Ebay (aka "bootleg") copy of WIS on your computer, it might be time to pony up the $20 and get it. Then ride the learning curve so you can find out exactly what those control units, modules, components and circuit relays are. THEN you can start to know wtf you're fighting.
If you don't have an Ebay (aka "bootleg") copy of WIS on your computer, it might be time to pony up the $20 and get it. Then ride the learning curve so you can find out exactly what those control units, modules, components and circuit relays are. THEN you can start to know wtf you're fighting.
I don't own a computer that WIS it works on. Is there a code lookup reference? To me it sounds like relay N10/1 on the front SAM module needs to be replaced. Just don't know what that means. I found a diagram, but it is not helpful.
Or maybe it is relay 87 that controls the SAM that is switching late?
What does your scanner tell you about the engine coolant temperature when you jump in first thing in the morning? Does it say the engine is the ambient temperature or does it say the ECU thinks the coolant is warm (and thusly not turning on the glow plugs)?
What does your scanner tell you about the engine coolant temperature when you jump in first thing in the morning? Does it say the engine is the ambient temperature or does it say the ECU thinks the coolant is warm (and thusly not turning on the glow plugs)?
Air, coolant, fuel temp = -10°C. Held the key in start position and it fired right up after a few chugs...but I had forgotten to turn on the glow plugs again after taking all the readings...oops.
The relay at the pictures position controls the module. The error says the relay is closing late. I believe it is in the box in the engine bay, second from the lower right. If anyone can confirm that is correct. It is for the module that fires off the glow plugs, and that makes sense. Also, looking up the current relay part number from mbparts it shows it was replaced with a new model that is sold out. Sounds like this is a known issue and they are selling out of the replacement part. W164 engine box
According to MB new relay p/n is 000 982 29 23
If your car has keyless go and that's how you've been trying to start it (just push the button!) maybe try the following to let the relay catch up:
pull the button out of the key fob socket
put in the key fob, turn the car to ON/RUN position without starting. Leave it there for a solid 10 seconds to let the relay activate and thusly the glow plugs can be allowed to do their job
Turn the key the rest of the way to "start"
Did it work?
Try swapping the relay with a like-one. See if the problem persists or follows the relay.
Relays are dumb - nothing special I personally haven't heard of this being a "known issue". If you need a new one - take it to your local parts store to match it up. There's nothing special about that relay where another brand wouldn't work just as well. Heck, that one isn't even German!
Closely inspect the relay spades and where they plug into for corrosion.
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