Automobile Parts User Manual

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.

/min. (28.2 m

/min.)