How to Speed Up the Trim of a Mercury Oildyne Style Outboard Trim Pump
Enhance the performance and speed up the trim of a Mercury Oil Dyne style outboard trim pump by following these steps. This guide includes adjustments to relief valves, optimizing the pump, and advanced techniques such as increasing voltage or using a speed controller. These changes should be done be experienced professionals.
1. Relief Valve Adjustment
Locate the Relief Valves: Relief valves are found on the pump in the reservoir area under the external UP and DN ports.
Measure and Record Settings:
Use a pressure gauge to measure current settings. Record the distance between the jam nut and the adjusting screw for accurate reassembly.
Adjust Pressure for Faster Trim:
Loosen the jam nut on the UP relief valve (associated with raising the trim).
Tighten the adjusting screw clockwise to increase pressure, speeding up trim operation.
Each full turn of the screw increases pressure by approximately 500 psi on the UP side, it's about 350 psi on the down side.
Retighten the jam nut to secure the adjustment.
2. Increase Voltage from 12V to 24V
Upgrading from a 12V to a 24V motor can significantly improve speed and responsiveness by providing more power to the pump.
Steps to Upgrade:
Ensure the motor is rated to handle 24V.
Replace or modify the power source (battery or transformer) to supply 24V.
Upgrade wiring and relays to handle the increased voltage and prevent overheating.
Advantages:
Faster motor RPM, directly leading to quicker trim adjustments.
More consistent performance under heavy loads.
3. Add a Speed Controller
Installing a DC motor speed controller allows you to fine-tune the motor’s RPM and optimize trim speed without permanently modifying the voltage.
How to Install a Speed Controller:
Select a speed controller compatible with your motor and voltage range (e.g., 12-24V DC).
Wire the controller between the power supply and motor, following the manufacturer’s guidelines.
Use the controller’s dial or software (if available) to increase motor speed as needed.
Advantages:
Adjustable control over trim speed.
Ability to balance speed and power consumption based on conditions.
4. Optimize Pump Size
Mercury-style trim pumps often offer various pump sizes:
.0098, .0187, .0246, .0321 CIPR (Cubic Inches Per Revolution).
Upgrading to a larger displacement pump increases the flow rate, allowing the trim to operate faster, provided the motor can handle the additional load.
5. Use Proper Hydraulic Fluid
Ensure the system is filled with hydraulic fluid compatible with the pump’s specifications:
Prop Power Trim Fluid or mineral-based hydraulic oil with a viscosity of 32-64 cSt (150-300 SUS) at 38°C (100°F).
Correct fluid reduces resistance and enhances speed.
6. Check for Debris or Air in the System
Dirty and or Air in the system can reduce efficiency and slow operation.
Clean and Bleed the System:
Cycle the trim up and down several times.
Keep the reservoir filled with hydraulic fluid during bleeding.
7. Upgrade Motor Performance
Use high-performance motors such as:
DC Permanent Magnet Motors (AE/BE) or Series Wound Motors (AM/BI) for increased speed and torque.
8. Review Circuit Type
Ensure the pump circuit (e.g., RR or RB configurations) is optimized for fast operation. Reversible circuits may require specific adjustments for speed.
Warnings and Best Practices
Always depressurize the system before making adjustments.
Do not exceed the system’s maximum rated pressure (typically 207 bar or 3000 psi) to avoid damage.
Use calibrated tools and follow all safety protocols during the process.
Consult an experienced mechanic.
By increasing voltage, using a speed controller, and optimizing other factors, you can significantly enhance the performance of your Mercury-style outboard trim pump.
Let us know if you need further assistance. Mike Hill at 714-697-1716
Flow Rate Differences for Gear Sizes
The flow rate differences for the various gear sizes (.0098, .0187, .0246, .0321) of this style hydraulic pump depend on the gear displacement, pump speed (RPM), and system characteristics.
Here are the flow rates of the gear sets:
.0098 in³/rev (CIPR):
Smaller displacement.
Produces the lowest flow rate, typically used for low-speed or high-precision applications.
.0187 in³/rev (CIPR):
Moderate displacement.
Produces higher flow than .0098 but remains efficient for medium loads.
.0246 in³/rev (CIPR):
Larger displacement.
Produces a significantly higher flow rate than smaller gears, suitable for faster actuation or higher volume systems.
.0321 in³/rev (CIPR):
Largest displacement available for this series.
Produces the highest flow rate, ideal for high-speed or large-cylinder applications.
Summary
A trim pump uses hydraulic pressure to adjust the angle of the motor. The system consists of an electric motor, a hydraulic pump, solenoid valves, and hydraulic rams (actuators).
The pump pressurizes hydraulic fluid stored in a reservoir, directing it to the rams, which either extend or retract based on the operator’s input. This movement tilts the motor up or down, allowing for optimized performance and fuel efficiency in various conditions.
These pumps are designed to operate efficiently under the extreme demands of high-performance boating. Most modern trim pumps handle pressures up to 2000 PSI, allowing them to lift heavier motors or respond faster in racing scenarios. Whether used in a 2-stroke Mercury V6 outboard or a MerCruiser sterndrive, Mercury Oildyne Style trim pumps ensure reliable and consistent operation.
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