Design And Function; Intake And Exhaust System; Preheater; D12C - Volvo D12 Service Manual

Group 25 Intake and Exhaust System

Intake and Exhaust System

Preheater

Selected versions of the D12 are equipped with a pre-
heater. Its purpose is to warm air in the intake manifold
when starting the engine. This heated air eases starting
at very low temperatures and reduces engine smoking
when starting a cold engine. The following conditions are
required to engage the preheater:
•
The parking brake must be applied.
•
The power take-off must not be engaged.
The preheater does not engage at coolant temperatures
 
over 10 C (50 F). At a coolant temperature of 10

(50 F), the preheating time is 25 seconds. At coolant

temperatures below –15
55 seconds. Preheating time increases linearly between
  
10 C (50 F) and –15 C (5
The post-heating time is always the same as the pre-
heating time.

D12C

The D12C is equipped with a new preheater. The func-
tion of the starting heater is similar for both vehicle
variants, but the location of the relay differs. The pre-
heater on both engine variants is grounded to the engine
block through the intake manifold.

Design and Function



C (5 F), the preheating time is

F).
C
Fig. 2: Preheater, D12C
Design and Function
T2006975
Fig. 1: Preheater
W2003281
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