Firstly , welcome to the forum .
Now , I may sound like the prophet of doom here , but please exercise caution .
I may have been particularly unlucky when I bought my 2003 C270CDI estate Avantgarde SE model a few years back . My car had just under 115,000 miles when I bought it , so only slightly more than the one you're looking at , and the consensus on this forum at the time was the 270 was the engine to go for .
Three weeks into ownership , the first diesel injector ( no 5 ) failed ( I was in Aberdeen for Christmas when it happened and had to drive the 150 miles home with it 'chuffing' , so it was knackered by the time I got back and took it to my local Indy ) , from memory that cost me something close to £500
A few months later the no 4 injector followed suit and it was the same again - at this point I asked for the others to be checked , and was advised no's 2 & 3 should be replaced too - so that was an £1100 bill - the injectors alone are/were something like £270 each from Mercedes for the genuine items - so the garage weren't putting a lot of labour onto the bill .
When I bought the car , it had the well documented 'bouncing door lock' syndrome - a new drivers door lock was something like £90
I was also advised of a worn ball joint - unlike on the older cars where you could by a £12.50 ball joint on its own and fit it , on these cars you have to buy the complete suspension control arm at £150+ , and that's just for one ball joint - there are a few !
The rear wash wipe unit gave up - I found that water had leaked into the motor unit , seizing it ( the screen wash is pumped through the centre of the motor unit and up the wiper spindle - clever idea - but when wear occurs water gets where it shouldn't ) an aftermarket unit from Eurocarparts was about £200 , but I never got round to replacing it .
The heater was always poor and the car ran cool - so the thermostat ( apparently a common fault ) needed replacing - I never got round to it . There is also an electric block heater which may have been faulty .
One of the 'keys' stopped working - wouldn't start the car - and the other didn't always lock/unlock the car - keys are more than £200 each from MB .
Latterly , the car started dropping into 'limp mode' randomly , would sometimes clear , usually on restarting - this was diagnosed as inlet port motor failure - look up 'swirl flaps' - this was potentially a major repair , although there is a modification which involves removing the inlet manifold and removing said flaps , then inserting a resistor to fool the ECU that all is well . The car still had this fault when I disposed of it . The 'official' repair involves replacing the inlet manifold and motor unit and is fairly labour intensive . Again , this is quite a common problem .
Also , towards the end , the glow plug lamp started illuminating with the engine running - this indicates one or more faulty glow plugs .
Lastly , on a trip to Wales to collect an engine for one of my other cars in my trailer , the fifth injector failed ( when I had already done a deal to trade the car the following weekend - so it had to go in for one final repair .
Besides the above , I had also spent a bit on routine items : new battery , five new tyres just after purchase and two more about 18 months into ownership ( I kept it just under two years and did about 40,000 miles in it ) , all the usual oils and filters , brake discs and pads etc - routine stuff done at home by myself and anything 'tricky' done by my respected Indy ( Merparts in Port Glasgow ) .
When I traded it , the rear exhaust box was needing replaced , just starting to leak at the back end .
All of the above defects were pointed out to the new owner before trading .
Good points ?
Well , to give its due , when running well it was smooth and quiet , the seats were comfortable and the heaters were excellent for my sore back ! I was slightly disappointed that they were only half electric , with the fore and aft movements still manual - this seemed very strange after being used to full electric operation in my W124 and W126 cars ! Fuel economy ( the main reason I bought this car - my first foray into diesel cars , although I'd bought my girlfriend a diesel W124 E250D about a year earlier ) was excellent , with the computer showing 47 mpg average pretty much all the time , and could be coaxed above 50 if i was particularly light footed . The car did feel nice and solid , and the bodywork was pretty good , despite the reputation for rust , for an ( at the time ) 10 year old car . One of the attractions of this car was that it had a factory detachable towbar , which I used regularly to tow my trailer .
Negative impressions , apart from the unreliability , were that it seemed very cramped and claustrophobic inside , with limited space in the back - but then I was coming out of a LWB S-Class ( W126 500SEL ) into this car - the outward visibility of the C Class seemed very poor , with thick A pillars so close that at junctions you could lose entire cars behind them ! Also a black car with a black interior seemed very sombre - once at a funeral I was asked by the staff at the cemetery if I was the undertaker ! If you need the estate and are coming from something bigger , also be aware that the C Class is only a 'lifestyle' estate and not a real load lugger : I previously had two W124 estates and before them a W123 estate which had much larger load areas ; also , every 'E Class' estate has self levelling rear suspension , so they stay level no matter what you put in the back - this is an option on the C Class and few of them have it ! I'm a photographer and videographer , and often carry a lot of photo/video/lighting/audio kit in my cars , and compared to my previous estates , the C Class struggled to carry everything . Oh , and when I bought the car , it had one of those horrid , skinny 'space saver' wheels - so one of the first things I did was go down to the dealership and buy a 'proper' steel spare wheel , which fitted straight in the well under the floor .
I was so disappointed with this car , I went back to a W201 190E ( I'd had two previously ) which I got cheaply as a restoration project , and ran it alongside the C Class for a year without spending much on it - the only significant fault being cylinder head corrosion - hence the new engine , now in and running sweetly ( and upgrade from 1.8 to 2.3L ) .
I swapped ( literally ) the C Class for a R129 300SL , which is what I'm currently running , and can see me getting another W124 estate at some point to complete my fleet with another load lugger . Speaking recently to the chap I swapped cars with , to remind him the C Class MOT was due , he told me it was off the road due to turbo failure ! ( I also have a friend with a C320 which is off the road for the same reason - but he has just bought a W123 300D to replace it ) .
My girlfriend's E250D was actually a very good car , although a bit pedestrian being a normally aspirated diesel , and she just felt it was too big , so she swapped it for a diesel Golf which was also a very good car . The E250D was sold onto another member here , he ran it for a while before exporting it to Hong Kong , which took it back closer to its origins since it was assembled in India !
Now , I may have been particularly unlucky with my C270 , certainly more than most , but all of the problems I outlined above are fairly commonplace and you will read of others on this forum who have experienced one or another of them - so please be wary , and give your car a good check over before buying .
I sincerely wish you good luck .
