Forum:
The 2.8 TD I have fitted to my Landie has the ACSD. How exactly does this work? I have the service manuals on CD but have not found a decent description. I understand there is a wax thermostat but how does it affect cold starts?
The 2.8 TD I have fitted to my Landie has the ACSD. How exactly does this work? I have the service manuals on CD but have not found a decent description. I understand there is a wax thermostat but how does it affect cold starts?
I was curious about this so
I was curious about this so did a few searches on Bosch VE cold start mechanisms. I believe the 2.8TD uses a Bosch VE (or Denso clone) injection pump. As I understand it, the ACSD advances injection timing according to coolant temperature by overriding the action of the transfer fuel pressure regulator. The increased transfer pressure causes the pump's internal timing mechanism to advance the cam roller assembly and inject fuel a few degrees earlier than would normally be the case for a given engine speed. Note the increased transfer pressure does not increase injection quantities, it merely advances timing to allow more burn time in a cold engine.
You are right in that a wax thermostat is used - this pushes against the cold start advance lever. A failure of the thermostat would most likely cause the injection timing to remain in a cold / advanced state