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Hey guys just purchased a higher mileage R550, I figured if I was going to buy a "minivan" it had to be a V8 one and after doing some research and driving 2 and a half hours I ended up purchasing this one;
I have some body work to do as well as the the arches beneath the protective film are rusting and the passenger rear taillight is cracked, moisture in the front corner lights and a couple other things that bother me.
Mechanically the typical rear hatch failing to lift on its own and not closing properly causing the interior light to be on when the button in the overhead controls is not turned to the off position, next up is the coolant temperature message comes on and the rad fan is blowing full speed whenever the vehicle is running but the temp of the coolant does not exceed 90'C, also wife mentioned that when the heat is turned on it is only blowing luke warm air, so thermostat? I assume that if it was the water pump my engine temp would be significantly higher.
The SOS system calling out can sometimes take forever(I haven't read much into this system I just know that my wife finds it annoying that she has to wait for it to do its thing before she can listen to music)
I am not particularly fond of the rims(or tires for that matter) so I intend on picking up some factory Mercedes wheels as well as maybe a little exhaust work so that I can hear the 5.5l
The R550 is going in this Friday to a reputable shop to have the first two issues looked at as well as a full inspection of the vehicle as the previous owner "changed all the fluids" but has no receipts to prove what he says he did when he took it out of storage. Now I need to buy some more tools and pick up a decent priced scan tool and Mityvac so I can get my hands dirty myself.
I have to say it is damn hard to find information on this particular vehicle, from what I gather pretty much any info on the M273 is relevant to the R550 and I should be able to use info regarding the other models for everything else on the vehicle.
Hey guys just purchased a higher mileage R550, I figured if I was going to buy a "minivan" it had to be a V8 one and after doing some research and driving 2 and a half hours I ended up purchasing this one;
I have some body work to do as well as the the arches beneath the protective film are rusting and the passenger rear taillight is cracked, moisture in the front corner lights and a couple other things that bother me.
Mechanically the typical rear hatch failing to lift on its own and not closing properly causing the interior light to be on when the button in the overhead controls is not turned to the off position, next up is the coolant temperature message comes on and the rad fan is blowing full speed whenever the vehicle is running but the temp of the coolant does not exceed 90'C, also wife mentioned that when the heat is turned on it is only blowing luke warm air, so thermostat? I assume that if it was the water pump my engine temp would be significantly higher.
The SOS system calling out can sometimes take forever(I haven't read much into this system I just know that my wife finds it annoying that she has to wait for it to do its thing before she can listen to music)
I am not particularly fond of the rims(or tires for that matter) so I intend on picking up some factory Mercedes wheels as well as maybe a little exhaust work so that I can hear the 5.5l
The R550 is going in this Friday to a reputable shop to have the first two issues looked at as well as a full inspection of the vehicle as the previous owner "changed all the fluids" but has no receipts to prove what he says he did when he took it out of storage. Now I need to buy some more tools and pick up a decent priced scan tool and Mityvac so I can get my hands dirty myself.
I have to say it is damn hard to find information on this particular vehicle, from what I gather pretty much any info on the M273 is relevant to the R550 and I should be able to use info regarding the other models for everything else on the vehicle.
-Kevin
@MrFaust Congratulations! The R looks great. There are alot of helpful R owners in this section. Also browse through the W164 and X164 sections of the site, because there are some similarities with the R.
Figured I'd keep you all up to date, so the vehicle went into a reputable euro repair shop Friday to have a inspection performed on the vehicle and get a diagnosis on the "Stop engine coolant light" the vehicle blowing only luke warm air instead of hot, and the rear hatch not working, works on its own on rare occasion.
They found the front/rear pads and rotors needing to be replaced
Minor leak from oil filter housing gasket, recommended replacement of oil filter housing as the new gasket may still leak after replacement due to the mileage of the vehicle(288000km)
Minor leak on radiator, radiator must be replaced( they say this will fix the coolant engine light and luke warm air, I'm still new to the platform but I would have guessed thermostat or water pump, although the coolant temp avg when driving is 85'C never exceeding 90'C)
Engine oil, trans, and front/rear diff fluid should be changed
Rear tailgate switch has failed, they want to replace the hatch lock(164-740-03-00) and hatch switch actuator(203-821-74-51)
Total cost including labor was about $5000
I've ordered new pads, rotors, the rad, and oil filter and will be looking after the repairs myself, although I may leave the other fluids for them to do
The lift gate has begun operating as it should, I read that you should only use the button on the fob to open and the button on the bottom of the door to close it as it can fault again being operated any other way, so that's what I've been doing and so far so good.
Changed the engine oil, she was pretty dirty!
Replaced both front and rear pads and rotors;
The torx screw on the first rotor I worked on stripped and I had to break the rotor off with a sledgehammer and use a pair of pliers to remove the torx screw, no other issues other than that.
I've decided to let a shop do the transmission, front and rear diff fluid, it goes in for that this coming Thursday.
The new rad I ordered has arrived but I'm waiting for the oil filter housing and gasket and thermostat to come in before I do that job.
Anything else I should do when I'm in there? I think I read water pump somewhere.
Last edited by MrFaust; 09-21-2020 at 09:44 PM.
Reason: Picture
Might be good to ask ML550/GL450/GL550 owners in the X164 and W164 forums. It's the same engine and drivetrain on a similar chassis. The M273 engine was a rare option in the already rare W251.
Thanks for the help guys one last thing(for now) is that the vehicle does not blow hot air or air conditioning, it seems to be whatever temperature is outside, would this be a fuse or relay? Heater control valve? Vehicle is out right now I just want some ideas so that I can hit the ground running when my wife comes home with it
Re: HVAC not blowing warm/hot, @MrFaust is the cooling system full? Check the reservoir when cold, and open the cap (when cold) to release vacuum or pressure. Are there any losses of coolant (leaks or through the tailpipe)?
HVAC not blowing cold can mean thermal expansion valve, a switch mounted on the compressor, or the compressor itself has gone go heaven. And/or low refrigerant, needing a recharge.
Re: HVAC not blowing warm/hot, @MrFaust is the cooling system full? Check the reservoir when cold, and open the cap (when cold) to release vacuum or pressure. Are there any losses of coolant (leaks or through the tailpipe)?
HVAC not blowing cold can mean thermal expansion valve, a switch mounted on the compressor, or the compressor itself has gone go heaven. And/or low refrigerant, needing a recharge.
The radiator has a minor leak and after inspecting the coolant reservoir I noticed gold flakes sitting in the bottom meaning some yoyo put stop leak in the system and something is probably plugged, fluid level in the reservoir needed a small amount of fluid, I guess I'm going to have to have the system flushed and hope the heater core isn't plugged.
I have a R550 as well for 5 years now, 278,000km. Good car all around, have done all of my own fixes, lots of help on the web with cars with similar engines, drivelines and suspension to figure out what is going on. I like RockAuto, FCPEuro; can cross-reference parts from other MB's with similar parts and save some $$. Get the shop manual, cumbersome to navigate as it resides on your computer and operates under a Windows 7 shell, but helps with part numbers, procedures and the like.
Picked up some nicer looking rims, replaced engine air filters, going to have some rust removed hopefully in a couple weeks. Updated the license plate lights, ordered new fog bulbs but they dont appear to be the right ones
Had the trans, front and rear diff fluid replaced
Replaced the leaking radiator and then had a coolant flush done, unfortunately the rad fan is still on full when the vehicle is turned on and I still have the Stop Engine Coolant light on
As far as diagnostic tools, would this be what I'm looking for as far as what I'll need to be able to diagnose all the issues this vehicle can have? Can I get the same functionality in something cheaper like one of Autels tools? https://www.aliexpress.com/item/4001...archweb201603_
Had the dealer troubleshoot the radiator fan running high whenever vehicle running and they believe the ECU is faulty stating they could not control the fan speed and there is no communication issue between the fan control and ECU. I've since ordered a China C4 Star Diagnostic system and plan on doing some digging myself as an ECU replacement is going to suck considering what they want for it.
Still no one seems to know how to diagnose the heat issue, which is annoying as hell.
Unplugging the rad fan does not effect the HVAC temp so obviously its not related to that.
Had to pick up a rental today and schedule to have a shop replace the oil filter housing/flush coolant/replace oil as the housing gasket has failed allowing a small amount of oil into the coolant and a good chance of the reverse although the oil level is unchanged, decided not to chance it.
Can't wait to finish dealing with this stuff
This video was pretty helpful in completing this job, something I'd like to add is that we don't have as much space between the engine and rad fan so it makes it much easier to pull the fan at the start.
Going on a bit of a rant here, took the R550 to the indy shop to have the coolant flushed, oil changed, and interior heat issue diagnosed and repaired.
Coolant flush and oil change was performed but today is the second day they have been unable to determine why the heat is only luke warm at best, I spoke with the technician working on the vehicle and they have confirmed that hot coolant is making it through the heating core(hoses to and from it are hot), the auxiliary pump is working, for some reason they diagnosed the rad fan running high all the time(I had told them when I unplugged the rad fan it did not effect the air temp in the cabin) and believe the fan control resister is shorted(Mercedes diagnosed it as faulty ECU), he disconnected the rad hose returning to the coolant reservoir and felt that there should be more pressure/flow so today they were going to remove the water pump to inspect the impeller, however as of an hour ago I was told they decided not to do this and were looking at something else(the tech was dealing with an engine swap so I could not speak with him) and that's where we stand today.
Tomorrow morning they will get back to me with what was found but the vehicle has to stay with them another day.
So the shop ended up backflushing the heater core and noted that flow through it appears to be poor and gave it back to us saying the heater core will have to be replaced, we have slightly better heat now after a $1150 bill lol.... Is it possible to flush the core with some type of solution that wont damage it and clear the crap out?
Picked up a used radiator fan from a 2008 R350 and plan on slamming that in tomorrow to see if they are right about the rad fan resistor being shorted.
So the shop ended up backflushing the heater core and noted that flow through it appears to be poor and gave it back to us saying the heater core will have to be replaced, we have slightly better heat now after a $1150 bill lol.... Is it possible to flush the core with some type of solution that wont damage it and clear the crap out?
Picked up a used radiator fan from a 2008 R350 and plan on slamming that in tomorrow to see if they are right about the rad fan resistor being shorted.
C4 Star Diagnostic tool on the way
Flushing a heater core doesn’t appear often on this or any other car sites where I participate. It would be a temporary remedy in my view.
Replacing the heater core on any vehicle is a fairly big job. Doable but a lot of the interior needs to be disassembled.
09-08-2020, 11:04 PM
