I mentioned on the other thread....to clean the ground points on the car....guess this was ignored...

Before running out and buying stuff, clean the ground points and learn how the glows work..

I believe you are having other issues with the car besides the glow plugs. If injection timing is off, clogged fuel filters, leaking fuel lines, bad injectors, bad ground connections, worn starter, tight valves, bad battery cables can all cause issues relating to starting.

The early glow system, relies on temperature switch in the head to tell the relay when to operated and when to not operate. Unlike the later models that have the temperature switch built into the relay under the hood and sense the temperature under the hood. This is why the older w123's glow plugs don't stay or come on as long as the newer models.

The glows don't start the car, they simply heat the prechambers to combust the fuel. The starter builds the compression up in order for the fuel to combust. A good running engine will start with out the help of glow plugs.

Metal expands when it is warm and shrinks when it is cold. Thus there is a bigger gap between the rings and the cylinder walls the colder the engine is. The glows help heat this area to expand the metal...

These cars, take a multitude of things running correctly for easy starting and smooth idle.

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