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D7.3L D-TRONIC DIESEL ENGINES - BRAVO MODELS
Page 9 of 90
ENGINE COMPARTMENT
WARNING
Boating standards (NMMA, ABYC, etc.) and Coast Guard regulations must be ad-
hered to when constructing the engine compartment.
Care must be exercised in the design and construction of the engine compartment. Seams
must be located so that any rain water, which may leak through the seams, is directed away
from the air intake system. Water, that runs onto the air intake, may enter the engine
and cause serious damage to internal engine and/or turbocharger parts.
IMPORTANT: MerCruiser will not honor any warranty claim for engine damage as a
result of water entry.
ENGINE COMPARTMENT VENTILATION
General Information
According to Boating standards (NMMA, ABYC, etc.) and Coast Guard regulations the en-
gine compartment ventilation system has multiple tasks. Included are the following:
1. To supply the engine with combustion air.
2. To maintain a low temperature in the engine compartment.
Fresh air should enter the engine compartment as low as possible and the heated air should
be discharged from the highest point.
If a separate air shaft (or similar) is used to provide engine compartment ventilation, or addi-
tional ventilation, care must be taken to prevent seawater and spray from entering it.
Combustion Air Requirements
Engine compartments with natural draft ventilation must have vent openings of sufficient
size and location to accomplish the tasks previously outlined.
Furthermore, in part, and according to, ABYC H-32-89 specification - “Compartment Ven-
tilation (Diesel)” states:
“Ventilating provisions and openings to the machinery space provided for suppling combus-
tion air shall accommodate the air requirements required by the engine manufacturer(s) for
each propulsion and auxiliary engine in that space. These openings may also function as
means of providing natural ventilation.”
IMPORTANT: The size of ventilation openings must be increased if any auxiliary
equipment is located in the engine compartment.
The combustion air requirement (per engine) for the specified engines at Wide Open
Throttle are shown in the chart below:
Combustion Air Requirements (Per Engine)
Model
Engine Air Requirements at
Wide Open Throttle
D7.3L D-Tronic and D7.3L D-Tronic LD
1000 ft.
3
/min. (28.2 m
3
/min.)