Exhaust System
Requirements
MCM (Stern Drive) Engines With Thru
Transom Exhaust
When designing and installing exhaust system, the
following must be observed:
IMPORTANT: It is the responsibility of the boat
manufacturer or installing dealer to properly lo-
cate the engine and install the exhaust system.
Improperinstallationmayallowwatertoenterthe
exhaust manifolds and combustion chambers
and severely damage the engine. Damage
caused by water in the engine will not be covered
by MerCruiser Limited Warranty, unless this
damage is the result of defective part(s).
Minimum Hose Size
Model
Single Outlet
in. (127 mm) 4 in. (102 mm)
4 in. (102 mm)
Dual Outlet
All (Except
Magnums)
5
Magnum
–
1.
Exhaust flanges must be of proper size to accom-
modate 4 in. (102 mm) I.D. exhaust hoses. They
must also be equipped with internal water shut-
ters, and use an exhaust flapper over each outlet.
Determining If Exhaust Elbow Risers
Are Required
On all engines to determine if exhaust elbow risers
are required, take measurements (a) and (b), with
boat at rest in the water and maximum load aboard.
Subtract (b) from (a). If (a) minus (b) is less than spe-
cified in chart, select appropriate size exhaust elbow
riser kit and exhaust extension kit that will correctly
position exhaust elbow.
2.
3.
The exhaust hoses and pipes must not be higher
than exhaust elbows at any point.
Theexhaustoutletmustbelocatedsothatamini-
mum of 1/2 in. (13 mm) drop per foot (305 mm)
downward pitch exists in the exhaust hose from
the engine exhaust elbow to the outlet. (This is an
American Boat & Yacht Council recommenda-
tion.) The drop must be constant so that a low
spot does not exist at any point in the exhaust
hose.
4.
5.
Exhaust outlet must be slightly above the water-
line with boat at rest in the water and full load
aboard.
Back pressure must not exceed 4 in. (102 mm) of
mercury when measured with a mercury manom-
eter to exhaust elbow outlets.
72700
Exhaust Elbow Measurement
a - From Waterline To Top Of Transom
b - From Highest Point On Exhaust Elbow To Top Of Transom
(a) Minus (b) Must Be
at Least
Model
All
13 In. (330 mm)
Index
90-823224--2 796
GENERAL - 7A-1
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1993, 1994, 1995, 1996, 1997 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
(4 votes, average: 4.5 out of 5)
Marine readers have rated 1993 1997 Mercury-MerCruiser GM V8 454 CID 7.4L and 502 CID 8.2L Marine Engines Service Manual Number 16 4.5 out of 5.0 based on 4 product reviews. Hugely helpful service manual! Perfect. Thank you!
Manuals are all Important for Technician
This book is invaluable if you do your own repairs. Great book.
Could not find a copy until a search brought me here.
Excellent print.
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