Mariner Mercury 105/140 JET, Service Manual

Page: 49 / 797

1D-14 - IMPORTANT INFORMATION 90-824052R3 JUNE 2002
Trim “In” Angle Adjustment
Some outboard boats, particularly some bass boats,
are built with a greater than normal transom angle
which will allow the outboard to be trimmed further
“in” or “under”. This greater trim “under” capability is
desirable to improve acceleration, reduce the angle
and time spend in a bow high boat attitude during
planing off, and in some cases, may be necessary to
plane off a boat with aft live wells, given the variety of
available propellers and height range of engine
installations.
However, once on plane, the engine should be
trimmed to a more intermediate position to a avoid a
bow-down planing condition called “plowing”.
Plowing can cause “bow steering” or “over steering”
and inefficiently consumes horsepower. In this
condition, if attempting a turn or encountering a
diagonal, moderate wake, a more abrupt turn than
intended may result.
In rare circumstances, the owner may decide to limit
the trim under. This can be accomplished by
purchasing a stainless steel tilt pin (P/N 17-49930A1)
and inserting it through whatever pin hole is desired.
The non-stainless steel shipping bolt should not be
used in this application other than on a temporary
basis.
WARNING
Avoid possible serious injury or death. Adjust
outboard to an intermediate trim position as
soon as boat is on plane to avoid possible
ejection due to boat spin-out. Do not attempt to
turn boat when engine is trimmed extremely
under or in.
a
a - Tilt Pin
Checking Trim System Fluid Level
1. Tilt outboard to the full up position and engage
the tilt support lever.
2. Remove fill cap and check fluid level. The fluid
level should be even with the bottom of the fill
hole. If necessary, add Quicksilver Power Trim &
Steering Fluid or automotive transmission fluid
(ATF) Type F, FA or Dexron II.
Trim Tab Adjustment
Propeller steering torque may cause your boat to pull
in one direction. This steering torque results from
your outboard not being trimmed so the propeller
shaft is parallel to the water surface. The trim tab can
help compensate for this steering torque and can be
adjusted within limits to reduce any unequal steering
effort.
MODELS WITHOUT POWER STEERING
Operate your boat at normal cruising speed, trimmed
to desired position. Turn your boat left and right and
note the direction the boat turns more easily.
If adjustment is necessary, loosen trim tab bolt until
trim tab moves freely (does not rub against locking
ridges). DO NOT strike tab to make adjustments.
Make small adjustments at a time. If the boat turns
more easily to the left, move the trailing edge of trim
tab to the left. If the boat turns more easily to the right
move the trailing edge of trim tab to the right. Position
trim tab in one of the locating grooves BEFORE tight-
ening bolt to prevent damage to holding mechanism.
Torque bolt to 40 lb. ft. (54.0 N·m) and retest.
MODELS WITH POWER STEERING
Trim tab adjustment is not required. The trailing edge
of the trim tab should be set straight back.