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Expansion tank replacement as preventive maintenance?
I coincidentally saw a guy taking apart the entire dash to replace the heater core - he revealed that he was doing so because the desiccant bag in the expansion tank had come apart and the heater core was blocked - he had already flushed 3 times and replaced radiator and thermostat etc., but their was still no cabin heat . The job looked absolutely horrible and I was wondering should I be concerned with a 2015 m350 with 160k miles and replace the expansion tank preventively? - is this a common failure? I installed new camshaft position censors and pigtailed the wires to the magnets to prevent potentially oil wigging through to the ECU as that is a relative common failure.
Thank you in advance
Martin
I coincidentally saw a guy taking apart the entire dash to replace the heater core - he revealed that he was doing so because the desiccant bag in the expansion tank had come apart and the heater core was blocked - he had already flushed 3 times and replaced radiator and thermostat etc., but their was still no cabin heat . The job looked absolutely horrible and I was wondering should I be concerned with a 2015 m350 with 160k miles and replace the expansion tank preventively? - is this a common failure? I installed new camshaft position censors and pigtailed the wires to the magnets to prevent potentially oil wigging through to the ECU as that is a relative common failure.
Thank you in advance
Martin
Do you know if he backflushed? or just flushed like coolant normally flows?
I do not know if he back flushed, but VW+ has similar problems and a full cooling system components replacement seems to be the repair. An expansion tank is 75$ and though you can get a lot of barbiturate's for those money it might actually make me sleep the best to just to replace it as it is an easy job. Thank you for confirming it is common for Mercedes.
Does this apply to the 2016+ models with the same engine too?
MB has been using the "silica pack" in its cooling system for decades. I am a firm believer that the coolant expansion tank/reservoir MUST be changed anytime the coolant is replaced, especially if a different fluid than the previous one is used. One thing is the silica pack wearing out "normally," and another is to have a chemical shock between two different coolants.
Well that makes me nervous, I have a 14' Bluetec with 285k km and I've done a coolant replacement with oem coolant. I haven't really heard of the W166 having this issue on the forums, is it really that common on the w166?
Well that makes me nervous, I have a 14' Bluetec with 285k km and I've done a coolant replacement with oem coolant. I haven't really heard of the W166 having this issue on the forums, is it really that common on the w166?
it can happen to ANY MB. The silica pack is standard part of the coolant expansion tank. I would need to search specifically for a failed W166 case to confirm.
We have 2 W166, and we have not changed coolant yet @96K, nor @146K, but I am very aware of the issue. The 2012 W166 is approaching 15 years old, so it will need a full coolant flush and a new reservoir.
Found an instance,
From another group, and a very collaborative MB tech there, Louis,
From Caleb Holmes (also a MB Tech in those groups),
I watched a video on what the schedule maintenance is for a typical MB taxi in Germany is and it suggested at 80,000 miles replace the expansion tank, water pump, upper and lower hoses - since they are mostly plastic.
At least the maintenance schedules for the 2008, 12, 14 and 15 states 150k miles/15 years. All our cars still have original water pumps. The 2008 had coolant service, and coincidentally the reservoir nipple was crumbling about the same time anyway, @140k miles.
Shorter service interval should not hurt, unless mistakes are made during installation or selecting replacements. The more the system is disturbed, the higher the chance something goes wrong.
I just acquired a 2014 ML550 with 92K miles, and the expansion tank was coated with dark gray goo. It still had the gold coolant in it, and I doubt it was ever flushed. It had broken down and I believe it was eating the surfaces off the radiator. I replaced the tank as well as most of the hoses and then did a full flush of the system.
I just acquired a 2014 ML550 with 92K miles, and the expansion tank was coated with dark gray goo. It still had the gold coolant in it, and I doubt it was ever flushed. It had broken down and I believe it was eating the surfaces off the radiator. I replaced the tank as well as most of the hoses and then did a full flush of the system.
Maintenance schedule for coolant is 150K miles/15 years (our MLs and the 2014 E are still on original coolant). It was still within specifications. I would not be surprised the silica gel pack in the tank broke down or someone mixed coolant types. For the 2014, I believe is the pink coolant (MB 325.6 / MB 326.6) for 2014+ ( https://www.fcpeuro.com/blog/engine-...-your-mercedes) .
Glad it did not clogged your radiator or created other issues.
it can happen to ANY MB. The silica pack is standard part of the coolant expansion tank. I would need to search specifically for a failed W166 case to confirm.
We have 2 W166, and we have not changed coolant yet @96K, nor @146K, but I am very aware of the issue. The 2012 W166 is approaching 15 years old, so it will need a full coolant flush and a new reservoir.
Found an instance,
From another group, and a very collaborative MB tech there, Louis,
Louis here, Thanks for the kind words!
Just a little more info on this:
166 chassis coolant reservoir has a 'hanging' desiccant POUCH (which is synthetic/plastic).
I'm not sure how many other chassis have pouches like these, but a lot of vehicles have a plastic box with slits on the sides (similar to charcoal filter cartridge in a fish tank?).
Although both types can fail, it seems like the POUCHES may be a little more susceptible to failing. The pouch has a 'hoop/loop' on one end and attaches to the top of the reservoir. My assumption is that the pouch can swing around when the coolant is low (probably moves from coolant flow too) and may cause a weak point in it. Thus tearing & letting the desiccant circulate in the system... then clogging it.
This is why we may recommend a new tank preemptively while doing repairs (depending on age/mileage).
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Expansion tank replacement as preventive maintenance?
