Measuring Exhaust Elbow Height; General Information - Mercury MerCruiser Product Applications Manual

Measuring Exhaust Elbow Height

General Information

The height of the exhaust elbows must be within the dimensions specified to prevent water
intrusion problems. Exhaust elbow risers must be installed, if needed, to obtain the proper
exhaust elbow height, and exhaust angle. Risers are limited to 203.2 mm (8 in.) on 8.1L
models and 152.4 mm (6 in.) on other inboard models. Measurement must be taken with
the boat in the water. It is important that the boat be loaded as outlined to simulate the
maximum loading conditions likely to be encountered in normal operation.
IMPORTANT: Exhaust elbow height is measured to the waterline inside of the water lift
muffler (instead of the water line outside of the boat) on applications so equipped. Refer
to Water Lift Muffler.
IMPORTANT: Load distribution recommendations are the responsibility of the boat
manufacturer. Any load distribution conditions that will affect the exhaust system must be
clearly communicated to the operator in the owner's manual. For example, the number of
people that can be located on the swim platform simultaneously should be included in the
manual, if this could pose a problem.
Measurements under all loading conditions must be within the following specifications.
MIE and V‑drive tow sport models
Tow sports inline models
Minimum Exhaust Hose Slope
Model
5.7 (350 cid), 6.2L (377 cid), 8.1L
(496 cid)
If the exhaust elbow height or exhaust angle is insufficient, modify the exhaust system or
install the appropriate exhaust riser. Refer to the appropriate Mercury Precision Parts
and Accessory Guide for part numbers.
The maximum exhaust riser height is specified in the table below.
Riser Options
Model
5.7 (350 cid), 6.2L (377 cid)
8.1L (496 cid)
90-863758060 AUGUST 2006
Minimum Exhaust Elbow Height
Model
Within 457 mm (18 in.) of engine Remainder of system (if applicable)
10°
Low
76 mm (3 in.) and 43 mm (1.7
in.)
51 mm (2 in.)
Specification
38 cm (15 in.)
33 cm (13 in.)
Specification
Medium
76 mm (3 in.) and 119 mm (4.7
in.)
152 mm (6 in.)
Exhaust System
3°
High
152 mm (6 in.)
203 mm (8 in.)
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