1) The fuel/exhaust mix is controlled by butterfly valves in the intake. These are moved by an electric motor - the "swirl motor". This can fail if contaminated by oil, causing an expensive, or at least very time consuming repair to be required. Oil vapour from the crankcase is recirculated into the air intake pipe to reduce missions. The oil in this vapour condenses-out in the air intake pipe, finds its way past an oil seal at the junction with the turbo, and drips down onto the top of the swirl motor. Preventative measures are :
an up graded intake pipe,
an extra jubilee clip around the pipe
the sealing of the old type seal (orange)
The latest cure/preventative measure is to fit a resistor to the swirl motor plug, disconnecting the motor completly from the system but not triggering the limp mode or a fault light
2) The alternator – similarly prone to oil damage as alternator sits immediately below the oil filler, There’s a small plastic guard available which shields the alternator from drips
3) Two small diesel supply lines, which are made from rubber are prone to cracking, allowing diesel leak (and also kill the alternator). Check these pipes are in good condition unions are tight and drip-free
4) When out for a test drive listen for any knocks from the front end (worn bushes)
5) Check if any of the lights are misted up especially the front spots (common)
6) The wheels…… the alloy finish rots (same with all Chryslers). The only long-term cure is to have them powder coated. If the car you’re looking at has corrosion, don’t dismiss the car, because any car you find with perfect wheels will suffer the same fate soon enough!
7) Remove the engine cover and check the wiring on the righthand side of the engine, his applys to all 300c's.
See here for more details
8) The rear ABS tone ring on the rear drive shafts are prone to rust, replacment by the dealer is a whole new driveshaft, but the rings are now availible on their own at very little cost
9) The latest fault, which is becoming is a oil seal under the inlet manifold, its not a small job to fix but a normal mechinic can do it, Look out for oil leaks down the back of the engine
The CRD models have a some of issues new buyers should be aware-of, don't worry too much ALL cars have there problems and with the 300C generally these seem to be preventable with a few precautions.