I have a 79 Mercedes 300D that has been causing me a few problems these past few mornings. It strated with the dashboard glow plug indicator light flashing for about 30 seconds once the car started, that progressed to it becoming increasingly difficlt to tart the car in the mornings (only the first start of the day, all subsequent starts where fine). Last week it would not start at all.

After a glow plug change and a new air compressor pump it semed fine on the first few starts. The new 'issue' is that the dashboard indicator light is flashing when the key is turned to the 'glow' setting and starting is kind of difficult. It is turning over first time, but needs a good few seconds to fire up.

Should I be looking at the relay?

Thanks