Volvo VNL 780 Operator's Manual page 351

T3008841
If necessary, once the engine has started, the preheater will reengage (post heating) for
the same length of time as the preheat time.
Engines Without Preheater
Engines not equipped with a preheater may, depending on coolant temperature, take longer
to start. If this should happen, DO NOT release the ignition key until the engine has started
(while still observing the 30 second maximum cranking time).
Ether Start
DANGER
DO NOT use ether or other combustible
starting aids on any Volvo engine.
Introduction of ether or similar starting
aids could cause a fire or explosion
resulting in severe property damage,
serious personal injury or death.
OPERATION 341