MERCEDES 230C PERSISTENT JERKING
QI have recently purchased a 1980 Mercedes 230C which, before I got it, had been standing for some years. Before starting it, I drained and refilled the tank with fresh petrol and then fitted a new battery. The engine started first time, but would not tick over evenly. I adjusted the points, which helped matters slightly. I then carried out an engine service and as well as replacing the oil and filters, also replaced the plugs, points, condenser, HT leads and distributor cap.
The tick- over problem having been dealt with, I discovered I now have a flat spot when accelerating and so I replaced the fuel pump. Unfortunately I still have the problem. Can you suggest what I should check next? David Conagon
AThe problem you have may be either fuel or spark related. Having replenished the fuel and replaced the fuel pump I would not suspect fuel delivery to be the problem. However, the diaphragm in the Stromberg carburettor may well have perished and I would suggest replacing this, and also checking the needle valve is free.
The other possibility is that the fault may be within the ignition system. Since you have already replaced the points and condenser along with the HT leads and cap, there may be a problem with the centrifugal bob weights. I would check that these move freely. It is possible that they have seized in place over the time that the vehicle has been standing. Staying with the distributor, the vacuum advance system should also be checked to ensure that this is operating correctly. So to sum up, I would replace the diaphragm in the carb as a matter of course given the age of the unit, and also check that the distributor advance and retard system is operating correctly.