Hello all,

I've started my search for a C55 AMG and thought it would be a good idea to have a buyer's guide for things to check when looking at the car for the first time.

From what I've read, here are items to look/ask for:

1. Oil consumption between oil changes - get an understanding of how much the car is using. Mercedes considers 1 qt/600 miles normal.
2. Valve cover and oil cooler leaks
3. Power steering pump pulley whine
4. Rust - not as pervasive on the C55 as it is on the C32s, but still worth checking for. What areas are more prone to rusting?
5. Heated seats working properly, as the bottoms are prone to failure if kneeled on the seat
6. Interior rattles
7. Climate control issues
8. Intermittent amplifier and stereo head unit issues
9. Engine mounts
10. Electrical issues with headlights/taillights
11. Service history - this is not specific to the C55 AMG, but oil changes, transmission, brake, and coolant services.

This is what I've come up with after reading about the C55. I'm sure I'm leaving things out. Please don't hesitate to correct anything if I have a misunderstanding about what are common issues/things to look for. If other members who have experience with this would like to pitch in, with more specific info as to what to look for, or how to check for it, that would be really helpful!

My hope for this thread is to become a comprehensive resource for anyone looking to buy a C55. I'll be glad to document more as I go through my search of finding a good candidate to add to my garage.

Thank you!

 

I just bought a 2005 CLK55 AMG with 108K miles. It has 2, 3, 5, 8. Had 9. 2 has been fixed twice and is back. Same with 5. Previous owner for 14 years was a rich guy who kept service records and had most of it done at the stealership.

Leaky valve covers are endemic. Mine also leaked LOTS of oil from the oil filter assembly. Independent mechanic fixed the leak, ONLY cleaned what he needed to right around the repair. What a mess.

I think these cars will be worth the struggle (If you can afford it). I plan on doing as much of my own labor as possible, but I am quickly learning that accurate diagnosis requires at least Xentry diagnostic setup and you need full dealer/certified diagnostic access for some things.

Good luck on the search!

 

Thank you for your response, when you mention 2, does it have both valve covers and oil cooler actively leaking? The valve covers are a prevalent issue (not exclusive to this platform) but they are relatively easy to address.

What symptoms did it present with the power steering pump? (other than the whine)

Are you planning on addressing heated seats or the amp issues? If so, what have you done so far? How frequently do the stereo issues present themselves?

I'm fairly mechanically inclined and this would be a 3rd vehicle so not looking to daily it. If it has to be down for a bit to address some of these things, I'm not overly concerned.

Thank you!

 

Really not sure about the power steering whine, I have many of these cars and the whine that is heard is mostly from the oil pump in the amg cars, and I believe that the ones that whine are the dual sump ones like the e class and c class. None of the 8 amg cars or non amg cars from this era have ever experienced power steering whine. Or sounds like the power steering pump but isn’t

 

I´ve read that if you turn your steeringwheel to the lock and hit the throttel hard, you can ruin your power steering pump.
Some ruin it at burnouts...

 

Keep an eye on the radiator too because the radiator ends are made of plastic and will break sometime.
I had to change mine because of that.

 

Interesting, good to know. I had read about people having issues with power steering, and my main concern is to not find myself needing a new power steering rack. That's one thing I don't really want to mess with.

I would guess age would cause the failure. Is it a big job to replace the radiator, or is it fairly accessible?

Thank you all!

 

No, it´s not a big job and it´s fairly accessible.

 

How common are alternator issues with the C55s?

 

It's somewhat common on M113 cars

 

I would say the alternators seem to go faster on the cars with more accessories. Seems to be around 100,000 miles for alternator issues. Seat module issues are far more problematic, as are power window switches. The fuel tank senders seem to crack as well.

 

As far as I know the first thing that breaks down is the voltage regulator within the alternator. I changed mine after 80.000 km
but still use the original alternator after 230.000 km. The next thing that goes is the bearings in the alternator that wears out, then you
have to change the whole unit.

 

Thank you all for your responses.

I'm happy to share I picked up a C55 AMG this weekend. I brought it home to Colorado and had a mostly uneventful trip.

At one point in the Utah desert, I lost all gauges, blinkers, power windows, and climate control. The steering wheel returned to its raised position to exit the car. However, the engine and transmission kept working. I made it about 30 miles (in which the odometer did not read a single mile, despite displaying the miles) to the next auto part store. I restarted the car and everything came back to life. I had them check the alternator and battery while I tested all the relevant fuses. First thing the guy from the auto part store said was "I hate German cars"

Luckily, the alternator was fine, but battery tested low. Slapped a new battery in and the rest of the trip went smoothly. I had a couple of power surges where I could see the headlights get brighter for half a second. Then yesterday, I drove over a pothole going 10 miles an hour and same thing happened where I lost all gauges. I checked the battery and it was not installed correctly so it was flopping around in the engine bay. The person who installed the previous battery did not properly secure it, and while replacing it in the parking lot of the auto part store I didn't realize there was a bracket in the tray. I'm hoping that's solves it.

It has a few small issues, namely valve covers are leaking, the key fob does not work unless you are really close to the infrared sensor (checked fuses in the trunk and they seemed fine), driver's heated seat bottom does not work, and there's a whining noise that matches the revs, I suspect one of the pulleys, but haven't properly diagnosed it just yet.

Nothing I didn't expect out of a 20-year-old German car. I'm loving it. It's an amazing freeway cruiser, sound is great, and it is very athletic! It has some deferred maintenance that I plan to address over time, but I started with an FCP Euro. My plan is to switch to Liqui Moly 5W40 - PO ran 0W40, engine filters, and alternator voltage regulator to hopefully address the power surge. The part is so cheap it is worth to do even as preventative maintenance. Oh, and windshield wipers





I will update my first post with additional items to check for so this can be a helpful guide for anyone looking to buy one of these cars.

Cheers!

 

Nice pickup!

I had my C55 for ~10 (?) years and ran it from 46k to 218k miles. Key items that I had:

1) Valve covers and the little covers on top of the covers can leak.
2) Engine pulley whine sometimes comes from the idler pulley. It's a cheap part and easy to replace. I replaced this 2 or 3 times.
3) 1 qt of oil per 600 miles is a little far fetched. I was losing about 1 qt every 3,000 miles, and that was towards the end of my ownership. This was due mostly to a leaking rear main seal, like many other Mercedes engines.
4) Rust normally occurs on the exhaust, certain steel components of the rear subframe, and the rear wheel suspension components
5) Front suspension arm bushings normally go out (mine at 120k)
6) Engine mounts can go out, but you're never really sure heh
7) I replaced a MAF sensor (that actually turned off the engine while I was in the middle of a turn, luckily I just coasted straight into a diagonal parking spot with no traffic around me)
8) I think I replaced a voltage regulator once, but honestly don't remember
9) Replaced the starter at ~215k or so
10) A/C unit and HVAC fan would sometimes randomly shut off for about 5 minutes, right when you needed it in the heat of summer. I was never able to replicate the issue, it would happen randomly once or twice a year.
11) Power steering pump whines a little, but it's normal, even with new CHF11S.
12) I don't remember if I replaced a front wheel bearing or not
13) The original Mercedes battery lasted 9.5 years. Since then I will only buy the original Mercedes battery.
14) Slight jerkiness in the 2-3 transmission shift was normally made better with new ATF. (I think it was the 2-3 shift...)
15) HID ballasts go out after a while (replaced 2 or 3 of those). The ballast controls the headlight leveling as well....

As for your car turning off, check the ground points of the battery to the chassis - sometimes this causes strange issues with the car.

 

Thank you @Viper98912 for all those points. I'll work on updating the first post with your notes and comments, those are very helpful!

Thank you for the lead on the ground points, I've checked them and they looked fine. I think the battery moving around when going over a pothole caused that intermittent issue - knocking on wood, we shall see!

 

I would second checking the ground. I had this exact problem with mine and after cleaning and re-tightening the ground lug in front of the ABS valve box, it never happened again.

 

Oil cooler was fixed by PO. Valve covers were leaky.
Power steering feels "lumpy" at low RPM. I changed the reservoir, which contains a filter, and flushed with new fluid. I have not properly tested since then.
Amp has been replaced with OEM equivalent, BUT it now needs to be coded to the chassis. I have the Xentry system to do that, but have not done so yet.
Heated seat is dead last on priority list. There was a note on one the the dealer receipts that is was previously "hard wired per customer request...". Sounds janky to me.
Basically, I am on a lengthy "while you're in there" train that will be resolved in a week or so. RMS, both Guibos, support bearing (there was a road-speed-dependent whine), changed Diff oil, full transmission service + blue-top shift solenoids for firmer shifts. This is my first automatic in a long time, not sure if it will grow on me or not, but might as well tighten it up "while I'm in there".