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MANUAL TILT & POWER TRIM

Theory Of Operation

The Power Trim system consists of an electric motor, pressurized fluid reservoir, pump and trim cylinder.

The remote control (or trim panel) is equipped with a switch that is used for trimming the outboard “up” and “down”, and for tilting the outboard for shallow water operation (at slow speed) or for “trailering”. The outboard can be trimmed “up” or “down” while engine is under power or when engine is not running.

Adjustments - Trimming Characteristics

NOTE: Because varying hull designs react differently in various degrees of rough water, it is recommended to experiment with trim positions to determine whether trimming “up” or “down” will improve the ride in rough water. When trimming your outboard from a mid-trim position (trim tab in neutral, straight fore-andaft, position), you can expect the following results:

TRIMMING OUTBOARD “UP” (“OUT”)

• Will lift bow of boat, generally increasing top speed.
• Transfers steering torque harder to left on installations below 23 in. transom height.
• Increases clearance over submerged objects.
• In excess, can cause porpoising and/or ventilation.
• In excess, can cause insufficient water supply to water pump resulting in serious water pump and/or powerhead overheating damage.

Excessive trim “out” may reduce the stability of some high speed hulls. To correct instability at high speed, reduce the power gradually and trim the motor “In” slightly before resuming high speed operation. (Rapid reduction in power will cause a sudden change of steering torque and may cause additional momentary boat instability.)

Excessive engine trim angle will result in insufficient water supply to water pump causing water pump and/or powerhead overheating damage. Make sure that water level is above gear housing water intake holes whenever engine is running.

Operating “Up” circuit will actuate the “up” relay (located under engine cowl) and close the electric motor circuit. The electric motor will drive the pump, thus forcing automatic transmission fluid through internal passageways into the “up” side of the trim cylinder. The trim cylinder/trim rod will position the engine at the desired trim angle within the 20° maximum trim range. The power trim system is designed so the engine cannot be trimmed beyond the 20° maximum trim angle as long as engine RPM is above approximately 2000 RPM.

The engine can be raised beyond the 20° maximum trim angle for shallow water operation, etc., by keeping the engine RPM below 2000 RPM. If engine RPM increases above 2000 RPM, the thrust created by the propeller (if deep enough in the water) will cause the trim system to automatically lower the engine back to the 20° maximum trim angle.

TRIMMING OUTBOARD “DOWN” (“IN”)

Excessive speed at minimum trim “In” may cause undesirable and/or unsafe steering conditions. Each boat should be tested for handling characteristics after any adjustment is made to the tilt angle (tilt pin relocation).

• Will help planing off, particularly with a heavy load.
• Usually improves ride in choppy water.
• In excess, can cause boat to veer to the left or right (bow steer).
• Transfers steering torque harder to right (or less to the left).
• Improves planing speed acceleration (by moving tilt pin one hole closer to transom).

Operating “Down” circuit will actuate the “down” relay (located under engine cowl) and close the electric motor circuit (motor will run in opposite direction of the “Up” circuit). The electric motor will drive the pump, thus forcing automatic transmission fluid through internal passageways into the “down” side of the trim cylinder. The trim rod will move the engine downward to the desired angle.

Trailering Outboard

Excessive engine trim angle will result in insufficient water supply to water pump causing water pump and/or powerhead overheating damage. Make sure that water level is above gear housing water intake holes whenever engine is running.

While operating “up” circuit, the cylinder rod will continue to tilt the outboard to a full up position or trailering.

Tilting Outboard Up and Down Manually

Before loosening the manual release valve, make sure all persons are clear of engine, as engine will drop to full “down” position when valve is loosened.

With power trim installed, the outboard can be raised or lowered manually by opening the manual release valve 3 to 4 turns (counterclockwise).

a - Manual Release Valve

Power Trim Flow Diagrams

TRIM UP CIRCUIT

b - End Cap
c - Electric Motor
d - Reservoir Oil
e - Down Circuit Pressure Relief Valve
f - Down Circuit Pressure Operated Valve
g - Filter (2 shown for clarity)
h - Shock Return Valve
i - Up Circuit Suction Port
j - Oil Pump
k - Down Circuit Suction Port
l - Oil Fill Cap
m - Shuttle Valve
n - Up Circuit Pressure Operated Valve
o - Manifold Reverse Suction Valve
p - Manual Release Valve
q - Manifold
r - Tilt Relief Valve
s - Tilt Relief Piston
t - Memory Piston
u - Shock Piston
v - Impact Relief Valve
w - Cylinder

Trim Up

When the trim switch is activated in the up position, the electric motor (c) begins to rotate the oil pump gears (j), the oil pump draws a small amount of oil through the filter (g) and through the up circuit suction port (i). The oil pump gear (j) rotation forces oil into the passages for the up circuit. Oil, under pressure, will slide the shuttle valve (m) against the down circuit pressure operated valve (f). The shuttle valve will mechanically open the down pressure operated valve, allowing oil from the down cavity of the trim cylinder to flow into the oil pump. This returning oil, from the down cavity, will supply most of the oil required for the up circuit. Oil in the up circuit is blocked from returning into the reservoir by the ball inside the down circuit suction port (k). The pressure of the oil will force the up circuit pressure operated valve (n) to open, allowing the oil to enter the passages inside the manifold (q) leading to the trim cylinder (w) up cavity. Oil is blocked from all other passages by the closed manual release valve (p). Oil under pressure will enter the trim cylinder below the memory piston (t). With an increasing amount of oil entering the cylinder, the memory piston contacts the shock piston (u) and forces the piston rod (a) up and out, raising the outboard motor. Oil on the top of the shock piston exits through a passage running down along the side of the cylinder and enters the manifold passages. The oil is drawn back into the pump (j) through the open down circuit pressure operated valve (f) and enters the pump as supply for the up circuit.

Tilt Circuit

Tilt Up

In the up mode, as the piston rod (a) extends from the cylinder (w), the memory piston (t) clears or uncovers the pressure relief passage. Oil from the up cavity will enter this passage and, if required, causes the tilt relief piston (s) to open the tilt pressure relief valve (r). This valve lowers the amount of pressure available to lift the outboard motor. With the engine in forward gear, and at high engine rpm, the oil pressure available will not be able to overcome the propeller thrust, limiting the trim range to below the pressure relief orifice. When the engine rpm falls or if engine is not in forward gear, the oil pressure is available to extend the piston rod (a) up into the tilt range.

Maximum Tilt

With the piston rod at maximum travel, and due to no rod movement, the pressure inside of the trim cylinder (w) will increase to the pressure required to move the tilt relief piston (s). The tilt relief piston’s “pin” opens the tilt relief valve (r). Up pressure flows into the trim relief passage, and returns back into the reservoir.

Manual Release

Manual Tilt

To manually tilt the outboard engine, the owner will need to back out the manual release valve (p) 3-4 turns. With the valve backed out, the internal passages inside the manifold are connected together. These passages connect both the cylinder down and up cavities together, along with the reservoir, allowing the engine to be raised or lowered. Piston rod (a) movement will continue until the manual release valve (p) is closed, locking the fluid inside of the cylinder and manifold.

Troubleshooting

Support outboard with tilt lock pin when servicing power trim system. IMPORTANT: After debris or failed components have been found (during troubleshooting procedure), it is recommended that unit be disassembled completely and ALL O-rings be replaced. Check ball valve components and castings must be cleaned using engine cleaner and compressed air or replaced prior to re-assembly.

IMPORTANT: Power trim system is pressurized. Outboard must be in the full “UP” position (trim rod fully extended) prior to fill/drain plug, or manual release valve removal. Refer to instructions following if disassembly is required when servicing. Follow preliminary checks before proceeding to troubleshooting flow diagrams (following).

Preliminary Checks

IMPORTANT: Operate Power Trim system after each check to see if problem has been corrected. If problem has not been corrected proceed to next check.

1. Check that manual release valve is tightened to full right (clockwise) position.
2. Check trim pump fluid level with outboard in full “UP” position and fill if necessary. Refer to “Bleeding Power Trim Unit”.
3. Check for external leaks in Power Trim system. Replace defective part(s) if leak is found.
4. Outboard not holding tilted position (falls down to trim position) indicates debris or defective components in trim assembly. Clean or replace components as required.

Hydraulic System Troubleshooting Flow Chart

OUTBOARD WILL NOT HOLD TILTED POSITION DURING REVERSE AND/OR TRAILS OUT DURING HIGH SPEED DECELERATION.

TRIM SYSTEM LEAKS DOWN WITH MANUAL RELEASE VALVE CLOSED.

Troubleshooting the Power Trim Electrical System

b - Trim Switch (Panel Mounted)
c - Fuse Holder – Accessory
d - Remote Control Wiring Plug Connector
e - Battery
f - Starter Bolt
g - Down Relay
h - Up Relay
i - Solenoid
j - Trim Pump Motor
k - Cowl Switch
l - Solenoid
m - 3-Pin Connector
n - Main Fuse Holder - Fuse #3

Trim Switch “UP” is inoperative, but the Cowl Switch “UP” does operate.

Cowl Switch “UP” is inoperative, but the Trim Switch “UP” does operate.

Trim Switch “UP” and Cowl Switch “UP” are both inoperative.

Trim Switch “DOWN” is inoperative, but the Cowl Switch “DOWN” does operate.

Cowl Switch “DOWN” is inoperative, but the Trim Switch “DOWN” does operate.

Trim Switch “DOWN” and Cowl Switch “DOWN” are both inoperative.

Trim Switch “UP” and “DOWN” are both inoperative, but the Cowl Switch does operate.

Trim Switch and Cowl Switch are both inoperative.

Trim system operates (motor runs) without pressing the switches.

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