Last week, my 1981, 240D, glow plugs stopped working. Thanks to Diesel Giant , I had two bad glow plugs.



Replaced the bad glow plugs, then went to start. All I got was loud clicking noise , from the glow plug relay. I just left the car and went inside, and later reading posts on glow plugs.


One suggestion, was to tap the glow plug relay. I did this and sure enough, everything works.


WHY did tapping the glow plug relay, cause everything to work?