What to look for when buying a 1996-2002 Mercedes W210: A Buyer's Guide

"There's nothing more expensive than a cheap Mercedes." - Owner, Cheap Mercedes

First thing's first, I'm not telling you how to buy a car. If you don't know how to check the tires, windows, Heat/AC, etc, you shouldn't be buying a car - I'm aiming to point out the car's biggest weak points to make your buying decisions easier. No surprises. 

We'll start this out by saying this isn't a definitive guide for those looking to buy into the W210. This is a culmination of information I've put together by having many W210's, servicing those W210's, and daily driving those same W210's. Even though I'm fairly well versed in the chassis and by driving them often, I've found each and every car is different in it's own right and some things may be wrong in different parts of the country and some things won't - it's strictly up to you to decide whether or not those problems are something that you're comfortable dealing with. If you see something in the guide that you feel should be added, leave it in the comments or send me an email and I'll add it in. There's always "something" that pops up, even as these cars age.

With that out of the way:

The W210 is a very do-it-yourself friendly chassis. If you're mechanically inclined, servicing a W210 is easy. So much so, that I'd rather work on any W210 than any of the previous "E" class cars (W123, W124). There are some computer systems that aren't accessible unless you have the Mercedes HHT (Hand Held Tester) or a higher end scanner (SnapOn Modus). While build quality definitely isn't on par with the earlier cars, the simplicity of diagnosing and repairing W210's outweighs the build quality when choosing it as a car to drive everyday. Don't get me wrong though, they're still tanks compared to other marques of similar years.

While they don't have the soft and plush ride of the earlier cars, I'd take a W210 over the earlier cars for trips over 4 hours. The soft, bouncy seats in previous generations tend to take a toll on the body with their general lack of support. W210 seats are firm and support you in the right places - you may not feel it initially, but your body will thank you for any extended journeys. The rack and pinion steering is very direct and feels nimble. They're also much easier and less expensive to repair/replace than the earlier recirculating ball box steering of the earlier cars.

Some engines (M119, M104, OM606 NA) carried over from previous generations, just ultimately refined and the best of breed...while some new engines were introduced (M112, M113, OM606 Turbo). You can't go wrong with any of them though, they each have their quirks, but they're all extremely stout and reliable engines.

We'll start with what you should be keeping an eye out for across the model range, regardless of year:

****Rust****

You guys that live where salt doesn't show it's face, consider yourselves lucky, but not free of trouble. If the cars have been anywhere in the rust belt, then there are some very key points to be looking for in terms of rust. Some of it strictly cosmetic, but it's the stuff you don't see everyday that gets you at the worst time. Prevention is key. MB going to water based paints in this time sure doesn't help the issue.

Spring Perch
The front spring perches on these cars are absolutely notorious for rusting away and then dropping springs, leaving the nose of the car on the ground. While it still may be driven to safety, it's not a pleasant sound or feeling to have your car dump to the ground. 

While this may "seem" alright and not catastrophic, it's what's underneath the Mercedes applied seam sealer that is going to get you. If you even remotely see some rust spots on or around your spring perch towers, get a wire wheel and get rid of all the seam sealer in the area to expose any rust. Coat with POR 15 or other sheet metal protective product and then apply a few heavier coats of rubberized undercoating over that to prevent future failures. When caught, problems are prevented.

Here's a perch that has finally detached itself from the unibody. 

Here's a picture of what was a small speckle of rust that was investigated further. Seam sealer removed and you can see how far the rust has penetrated. 

A completely severed spring perch. This get's bad and is a fairly easy check when buying a W210. Take a screwdriver and start stabbing away around the spring perch. If you get stuff that's flaking away, make it a point to either prepare to deal with it, or run away. 

This is a Mercedes technical bulletin on priming the new metal surface when redoing the spring perches.

Outside of MB, there are a few aftermarket suppliers of new stamped spring perch replacement panels. Fitment is generally good with whichever route you go, as long as the welding (riveting) and prep work is done properly, it'll last the lifetime of the car.

This is the "direct from MB" document on the new procedures for spring perch replacement.
https://drive.google.com/file/d/0B1msLYvXfXNpMjNmejJTR1NiTzg/view?usp=sharing

Front Lower Control Arm
This one may not show it's face as easily as the spring perch, but when it fails, it's a bit more catastrophic if you're at speed. What happens is the outermost portion of the control arm, where the spindle meets ball joint and ball joint meets control arm, snaps clean off. This doesn't happen on new parts due to their redesign, nor does it happen to cars that are void of rust. All happens because of some terrible drainage holes in the control arm itself. They get clogged, they keep water and debris for ages, and they weaken the welds and snap off.

The best and only method of checking this properly is to get the car up in the air, take the wheel off, and start stabbing the drainage holes with a very thin screwdriver to punch through any debris. 

You may get lucky and not lose the wheel completely, but don't count your chickens before they hatch. 

Here's a picture of one that is still together, but about to pop. 

Body Rust

I'm going to put this as blunt as I can, these cars are apocalyptically rusty. There are so many places for it to rust, that if a W210 doesn't have rust, I'll be wary. You should be too.

Fender Rust
Front fenders are known to dumbo ear at speed when the lower mounting screws completely rust off and let the fender fly free in the wind. It's just bad water drainage. If you ever have a chance to just remove the fenders from your W210, get in there with a wire brush, POR 15 and some heavy doses of undercoating and you'll be fine.

Most of this is caused by years and years of debris collection in between the fender and trim pieces and vibrations rubbing through the paint. Standing water and salt expedite the process and you'll have floppy fenders in no time at all. Usually, the mounting peg behind the fender itself will be rusty too, but not to the point where it can't be treated and used to mount a new fender.

The fender lips on all four corners are also prone to rust a lot. Thin paint, poor metal treatment and many rock chips make these areas more prone to rust than anywhere else on the car. Rusty fenders aren't a huge deal breaker for me, rather, they're letting me know there's more than I should be looking out for. 

Doors

Yes, doors. They suffer some odd fate of having random rust bubbles popping up out of no where. Most of it is centralized around the very bottoms of the doors and along the trim pieces. I'll drill a few 2-3mm holes along the bottom of the door to aid in water drainage. If I have the door panels off, I'll clean out the inside of the doors and coat the bottom of the door with POR 15, or just some random spray paint that will provide an additional layer before the water get's down to bare metal. The trim pieces suffer from trapping debris and vibrating it down to metal. Those areas rust and if left unattended you get catastrophic results to the door's structural integrity. 

This is a rather extreme example of what happens, but you get the idea. It CAN happen.

This is what "usually" happens if the rust in those areas get bad enough. Definitely requiring a new door because this isn't worth saving. 

Mercedes does have a recall campaign for the doors. Only, it's literally just wiping some excess silicone sealant off the bottoms of the doors as they trap water. Service campaign 200503005 


Headlight Buckets
The area behind and around the headlights is a terrible spot. The drainage plugs in those areas get clogged up and leave standing water behind, leaving all sorts of problematic, oddly difficult to repair rust.

This is how you'll usually find the headlight area on rust belt cars. This is relatively simple to repair if it hasn't completely rusted through and you'll be able to do it in a few hours. You can get a paint matched aerosol can from paintmatch.com or some other online retailer and once you've removed all the rust and prepped/primed the area, spray away. It's not really a vital area to look out for, but it's somewhat easy to see on either side of the car if you really look for it.

Same goes for under that same area. 

In general, there are few other places the W210's rust. Everything beyond these areas is pretty much standard rust for Mercedes cars. Look around the rear subframe bushings for excessive rust (difficult to repair) and get a general idea of how the bottom of the car looks. Rockers usually stay solid, as do the floors. Keep an eye out for rust and you should be in good shape. Drivetrain's usually last longer than the bodies of the cars themselves, thankfully.

Overall

722.6 Transmission
So the 722.6 5 speeds are electronically controlled. They're a super stout transmission and rarely fail mechanically. They're the 1st in line with the Mercedes "sealed for life" service campaigns, which is a huge sham. The transmission should be serviced every 30k miles - filter and fluid draining. Try finding a car that has had it's transmission serviced often. Aside from that, the transmissions have a conductor plate that usually fails before anything else. It will set the transmission in limp home mode (2nd gear only) or it will be stuck in whichever gear it failed in. With conductor plate replacement and a transmission control module reset, the trans will be good as new. The last two W210's I've had I bought with "blown" transmissions. Only to replace the conductor plate and have two of the most reliable W210's I've ever owned. The transmissions also have an o ring and plastic plug that go into the transmission that will leak trans fluid - sometimes that fluid will wick up the wiring harness and get into the TCM, causing a failure - though it's rare.

Window Regulators 

You'll mostly find the rear regulators going out on all W210's. This isn't year related, it's just a fact of life. It's not a particularly weak design, as when the window tracks are lubricated every so often, window regulator replacement is a moot point. The main plastic guide breaks away when it gets caught up on a poorly lubed window track. Every W210 I've bought had a broken rear regulator at some point in it's life. 

Sunroof 

Broken sunroofs are common as well. They're not too difficult to repair, but they have their moments. Frequent use usually prevents failure, believe it or not. There's no lubricant for the sunroof sliders, as they run along a polished metal surface on felt pads. Not using the sunroof frequently gums up the sliders, the sliders grab and the sunroof cables buckle and break out of their mounts. If the sunroof opens, awesome. If not, there are a few websites and DIY articles that show you how to go about fixing it. The best thing you can do is to open the sunroof all the way and take a clean rag or a couple q-tips and clean the sliding tracks. They're polished and look chrome, clean them of and use your sunroof once a week or so.


Heated / Self Dimming Mirror Delamination
The heated and self dimming mirrors on some cars equipped with them delaminate and the fluid that MB used in them leaks out and creates a fishbowl look. The mirrors turn brown when it's starting the process and it'll look like brown liquid sloshing around when it finally breaks through. It's very unsightly and replacement lenses for the self dimming is expensive. There are stick on replacement mirrors on eBay for around $15 and they'll somewhat transfer the heat during the winter. You lose self dimming, obviously. 

Front Suspension Knocks / Squeaks 
In addition to those front control arms catastrophically failing now and then, the front suspensions develop on odd deep knock when going over bumpier roads. Luckily the knocking is usually an easy fix: sway bar links. They wear out every 50k miles or so, not a huge ordeal in cost or time to replace. Should be about 45 minutes at most to do both sides. Front control arm bushings go out at the normal rate, crawl under the car and check for cracking in the rubber. Cracking = replace. Lower ball joint boots should be soft and relatively pliable. If they're leaking grease, they need to be replaced ASAP. They're not expensive and take about an 1-2 hours per side dependent on proficiency. Same story for the upper ball joints. 

Key Fobs
Replacement keys are about $230, so take care of yours. The early cars with the switchblade keys have sensitive tumblers. Don't have a janitorial set of keys hanging from your key ring when running your W210 - the tumbler will wear prematurely and failure means you won't be able to turn it. If you replace it as preventive maintenance the part is $70, if you replace it because you can't turn it, expect the repair to reach $1200 + any tow fees. I'll replace the battery's in the fob every 2 years.

Early cars also utilize infrared receivers in the door and trunk. They have some cheap plastic-like glass that will wear out and become very brittle. When working, opening the car a green light flashes, when closing a red light flashes. If you're not getting any flashes from the sensors, then they've gone kaput. Replacement door sensors are about $380, trunk sensors are about half. Or if you can live with them not working, free.

This is how the broken IR sensors look. Once they get to this point, all hope is lost.

Vinyl Interior 
Some early cars had some cheap vinyl armrests that wore through over the years and get sticky and really unsightly. Late cars had leather stitched stuff that lasts longer and wears much better.

Interior

Seat bolsters wear from getting in and out of cars. It's more prevalent on drivers sides. Same deal, but the B-pillar trim pieces will wear away if the seat is set further back (tall people). Headliners can sag, although it's extremely rare. Lift up the carpets and make sure they're dry - if they're wet, the sunroof drains are clogged and most likely leaking. If the rear headrests are up, test the button on the dash for auto down. If they don't drop down instantly, there's a vacuum leak.

Catalytic Converters
They just get noisy. They break away from their mounts and start rattling up a storm. Usually you'll hear them causing a ruckus when you're in one spot at idle. You can give it a small test by holding your foot on the brake and trying to accelerate a bit, if they're rattling away, guess what? Cat time.

Instrument Cluster Pixels
This goes for just about every single Mercedes with digital clusters. You'll get dead pixels on the instrument clusters. It may be one line, or all the lines - it's up to the cluster to decide which ones it doesn't want to display. It's relatively simple to fix and there are many companies that do the repairs for not much money. More of an annoyance than anything else.

Brake Lamp Switch
A faulty switch will throw ABS and ETS lights on the dash. Super simple and cheap fix!

MODEL SPECIFIC 

DIESELS
The OM606 diesels are fantastic engines. Smooth power delivery, much quieter than earlier Mercedes diesels. They aren't without faults though. Although, their faults are small and annoying.

Glow Plugs
The 606's use really long glow plugs. The glow plugs also have an odd taper at the sealing end that doesn't seat too well and let's some soot stop up the threading a bit after many heat cycles. This causes problems come time for removal because they're known to get stuck in the heads. Often times requiring cylinder head removal for replacement. If anyone has followed my posts on replacing these, the best trick ever is to plug in the block heater for a few hours before doing the job. I used my 20v Dewalt 3/8" impact driver to break the plugs free then just spun them out by hand. The biggest thing is heat, the hotter the engine when removing the plugs, the better for you!

Fuel Lines
Not sure why Mercedes decided to use plastic fuel lines on these, but what's done is done. There are about 6 different plastic fuel lines scattered all around the injection pump to supply and transfer fuel between various components. There are twice that of O-Rings used to seal these plastic lines. With modern day Biodiesel and people attempting to run vegetable oil through these very precise diesel injection systems (rather than the more crude systems in earlier generations) - the orings deteriorate rapidly and cause air and fuel leaks. Luckily, it's fairly easy to spot air leaks on these engines because of the plastic lines as you'll see air bubbles flowing through them. The same air leaks can cause the engines to not start, or start roughly. Repair is replacement of o-rings and possible fuel lines if they're brittle.


Shut off Valve
The shut off valve suffers the same problems with fuel leakage. There's a single O-Ring behind the valve where it attaches to the injection pump. Fuel can leak profusely from this spot. Just as well, a failed SOV will struggle shutting the car off and will throw fuel temperature codes. An annoyance, but it's about a $115 part on eBay / AutohausAZ.

EGR

EGR's on these are sensitive and allow dirty sooty exhaust into the intake tracts and usually clog them up. On naturally aspirated cars, you can block off the exhaust outlet with a block off kit and then route the EGR so it takes in fresh air from the air cleaner box. This works well because the car will still think everything is working correctly, only it will be taking in fresh clean air. On turbo cars, the EGR is a bit trickier - there are a few forum posts all around that show a few electrical modifications you can do to make the EGR function differently.

Resonance Flaps
Because the EGR's soot up the intact tracts, the resonance flaps in the intakes get stuck and will throw check engine lights. They're usually remedied by removing the flaps, soaking them in acetone and taking a brass wire brush and getting the soot off. Make sure the flaps hold vacuum and open/close properly is another step in making sure they're in good working shape before reinstalling.

Vacuum Leaks
There aren't many vacuum lines on the OM606 as it's mostly electrical (which is nice). Those vacuum lines that are present are often overlooked and will cause some odd problems with the resonance flap system. Replacing lines is a surefire way that you won't have any problems.

GASSERS

M104

Sans V8 cars, the M104 straight 6 is the smoothest running of them all. Though, isn't without faults. 

Timing cover

The front upper timing covers leak profusely and often. If resealed properly, the seal job will last about 50-60k miles. It's fairly easy and should only take about 2 hours to do the job. You can't use a ton of RTV as that's what causes more leaks. Being frugal with RTV or using the proper Mercedes sealants (or something similar) will yield great results.

Head Gasket
When the engines were first assembled, the head gaskets were somewhat weak. Within about 100k miles of heat cycles, the right rear corner of the head gasket will start leaking oil. Rarely do the gaskets pop and have coolant mix with oil - it happens, but rarely. New gaskets from Mercedes come with reinforced corners and shouldn't have to be done again for the lifetime of the engine.

Electronic Throttle Actuator (ETA) 
This is more prevalent on the 96 cars than the 97's - but the early throttle body's had some biodegrading wiring harness issues that affected the ETA wiring as well. With the car's age, chances are it's been replaced already, but if car has service records, comb through them really fast and see if you can come up with something.

Wiring Harness
Again, this really doesn't affect anything 98 and newer, early cars had odd biodegradable wiring harnesses. You'll find this across most German marques as it was some sort of attempt at helping the environment - only to make it worse because they had to make twice as many harnesses to replace the junk!


M119
M119's are super smooth, super reliable and super easy to maintain. They are legendarily reliable and have racing provenance. They do take up quite a bit space so they're a bit tight when you need to do something, but they're a great mix between great everyday power and fuel economy.

Cam OilersFor some reason Mercedes changed over from aluminum cam oilers to plastic in 1993. Why they did that, who knows. I'm sure it couldn't have saved them that much money in the mass production process. The plastic oilers will crack and break off and won't do their job - you'll get valve tick. Common practice is to find the early set of aluminum oilers and throw them on for essentially a bulletproof set up. Or get a new set of oilers from Mercedes and replace them every 100k miles or so. Not a bad job once the valve covers are removed.

Rear Main Seal
Not sure why this goes out frequently on these, but there's really nothing to do but replace it, or deal with a leak. A couple drips here and there for the rust belt guys is considered rust proofing, so take it for what it's worth.

That's it, really. The engines are damn near bulletproof. Timing chain guides get brittle like everything else and SHOULD be replaced every 200k miles or so and you'll get another 200k out of them. I wouldn't try to test the longevity of timing chain guides, not worth jumping a chain.

This is for both the M112 V6 and M113 V8 

Harmonic Balancer Recall Campaign No. 2005020003
Please make sure the car you are looking at has had this recall done. It will save you a headache, you can call the 1-800 Mercedes number with the VIN and check if the recall has been done on the car in question. 

M112
The M112 gets amazing fuel economy and have fantastic usable power. The 2 spark plug, 3 valve design makes for great performance from an otherwise very small package. Though, they aren't as forgiving as earlier engines for those individuals that don't maintain their cars very well.

Oil Cap Check
If you pull off the oil fill cap and see a white gooey substance, don't be afraid, it's not a blown head gasket! If the engine isn't allowed to get up to full operating temperature to burn off any water vapor in the crankcase, you'll get a milky substance hanging out at the highest point in the engine (oil cap). Wipe it off and drive your car further.

Any more than this and you REALLY need to take your car on a long trip.

Sludge
Carrying on with the whole maintenance and oil ordeals, the M112 (and M113) are known to sludge up rapidly if their oil services aren't done frequently. Mercedes and everyone on the planet will tell you change the oil every 7500 miles or so with synthetic. Screw that, I want my engines to last. Change oil hot and change oil often. My M112's get 0W-40 Mobil 1 and fleece filters every 5k miles - on the dot. Have had NO issues with sludge, ever. None. Zip. Nada. Don't buy into the sucker scam to ruin your engines. Pay the extra couple bucks or buy something Japanese.

Crank Position Sensor (CPS)
This will totally knock out the car. They're about $40 and can strand you anywhere. About 15-20 minutes replacement time. Dig through service records or ask the owner if it's ever been done - if it hasn't, JUST DO IT! Totally worth not getting stranded.

Outside of the harmonic balancer and sludge issues, the M112 is honestly an engineering masterpiece, internally.

M113
The M113 is the cream of the crop next to the M119. 2 plugs per cylinder, 3 valves each, it's a smooth and powerful (less powerful, but more torquey than M119) V8 bundle of joy. It returns slightly better MPG's than M119s and it's much more "drivable" than M119 cars, but that's mostly due to more electronic wizardry. It's a bit more expensive to maintain, but in my opinion, if this is going to be an everyday driver car and not some performance machine - who cares.

Sludging
Same deal as the M112's. Change your oil and don't fall victim to the extended oil life range craze of synthetic oils. Change oil hot and change oil often. I can't stand how many cars I've had come around that have had sludging issues and improper oil pressures and scoring camshafts.

Crank Position Sensor (CPS)
This will totally knock out the car. They're about $40 and can strand you anywhere. About 15-20 minutes replacement time. Dig through service records or ask the owner if it's ever been done - if it hasn't, JUST DO IT! Totally worth not getting stranded.

WAGONS

All the above applies for the wagons. They're 100% the same aside from being a foot or so longer and not having any rear shocks. That's right, no shocks. Wagons came with hydraulic self leveling SLS suspensions. Instead of conventional shocks, they have hydraulic rams with small reservoirs that act as the shocks. They're totally amazing when loading up the back or when towing. If the US got wagons in diesels, I'd be ALL over them. Though I won't discount a nice one when it shows it's face.

There are a few things to look out for when strictly buying a wagon - mainly having to do with the rear self leveling suspension.

Take the car over as many speed bumps as you can - if the rear feels bouncy, or extremely stiff than the self leveling accumulators are toast. They're not difficult to replace, just fairly time consuming. Get Mercedes or the best aftermarket than you can find, cheap replacements will only last about a year.

When looking at  wagon, load up the back as much as you can and rev up the engine to around 2k rpm. The rear should lift up to standard height within a minute or so. If it doesn't life up, there's either a weak pump (rare), the self leveling valve has a leak or has failed. They're more expensive fixes than the accumulators, but they're rare.

The actual hydraulic shocks themselves don't really fail (I've never seen or heard of one actually failing). What will happen is they will leak externally and drain your hydraulic system. That's about it.