Well for the car itself without the electronics it is easy any Car Manual place will be able to supply what you need.

The D-Jet Fuel Injection system is a different story though I've yet to find one anywhere.

There are two major modules in the car one is the Ignition module which in the 114/115 series Chassis is mounted at the front of the battery carrier on a plate that bolts onto the very front and hides the Ignition Module between the front inside of the engine bay and the battery rack. The other is a big unit which is behind the kick cardboard on the left hand side of the passenger compartment just in front and below the hood release.

The ignition Module can be replaced with a kit from Jaycar and it has the same contacts so it is an easy fit no extra wiring involved and costs about $50.00 AU I was quoted by Mercedes that one was available EX Germany but they had no idea of the cost as they had not sold one for a very long time but if should be somewhere around the $3,500.00 AU + GST as you can see the Jaycar unit is the best option.

The engine management module in another story though and you have to use one from Bosch that sought of fits the car that means any 6 Cylinder unit from the wreckers will most likely work.

If the battery is dead the car WILL NOT START so replace the battery first with a known good one and go for one of the bigger ones as these things draw quite a lot of power to start. It just might cure your problem, I know it did for me on a 116 280 SE and it didn't matter that the owner had left it there because it wouldn't start for 3 years and then her son tried to pulverize it into submission by attempting to jump start it of a 24 V truck. A new battery and it worked perfectly although I would never recommend this type of thing.

There are a set of points in the side of the Distributer which quite often give you problems as well because they loose spring tension and start to float at any sought of engine speed. While a bit of a pain to change they are not expensive and are very easy to fit after you have pulled the distributer out or removed the rocker cover which will allow you access to the 2 screws which hold them in. Removing the Distributer is the easiest way to do it though.

There is another trick with these cars if they still have the black plastic bit between the fuel tank and pump at the back of the car and the tank has been emptied completely these things do not allow the fuel to flow through until you have disconnected the fuel line at the pump and let some fuel flow out.

Actually in comparison to a lot of the EFI cars that are around now these Electronics are fairly robust and can take a lot of abuse so I really would start with the simple things first and work my way back from there. The fuel filters are also another potential problem as they can clog up if you have used contaminated fuel.

I've also seen the Ignition Modules off the latter cars 116/123 fitted to these cars as well they have a coaxial points lead which just pushes into the module and another plug with 4 wires coming out of it. A cheap replacement from the wreckers but a bit harder to wire in. The only down side is the points lead is part of the points and costs around $150.00 AU it is actually very similar to the original points lead in the 250 CE but instead of ending in a 2 pole cap it is split to an earth lead and the points lead at each end.

Also always check the Cam Chain as these do wear and I have seen instances where the Iginition get so far out of timming that the car will not start. But start by removing a fuel line {I find it easiest to pull one from the cold start injector on the inlet manifold and see if any fuel flows.} If not then check that the fuel pump is actually running and pumping fuel. You can run a power lead back to these and just check that the pump actually runs and if you crack a fuel line on the output of the filter you'll be able to see if any fuel is geting through. If not have a good play around there and check that the fuel pump is actually getting fuel and that the filter has not become blocked.

Also go over every earth connection you can find pull them off the body and reconect them after cleaning both the connectors and the body. There are a whole bunch of brown wires earthed on the left hand side under the dash which can give problems. Also if tyhe fuel pump is not running check the earth as I've seen cases on other cars where these have failed and stoped the pump from running. If there is any doubt run another earth wire to a different earth point.

I hope that is of some help to you.

Col