Mercury MERCRUISER - Testing the Exhaust System; Through-Transom Exhaust Back Pressure

Exhaust System
Page 6A-24 90-863758060 AUGUST 2006
7. Slowly take the finger off of the end of the hose to let the water level stabilize. The water
will seek the level of the water outside the boat. Keep the hose close to the exhaust
elbow and as vertical as possible.
8. The measurement between the water in the hose and the top of the exhaust elbow is
the exhaust elbow height. The maximum riser height is 20.3 cm (8 in.) on 496 models,
15.2 cm (6 in.) on all other models.
24866
a
b
Typical vertical water lift muffler
a - Minimum exhaust elbow height
with maximum load
b - Clear hose for measuring waterline
24867
a
b
Typical horizontal water lift muffler
a - Minimum exhaust elbow height
with maximum load
b - Clear hose for measuring waterline
Testing the Exhaust System
Through‑Transom Exhaust Back Pressure
IMPORTANT: Mercury MerCruiser recommends checking the exhaust back pressure on
all new applications with through‑transom or through‑hull exhaust to ensure that it is within
specifications.