Mityvac MV8255 Selectline Dual Vacuum/Pressure Hand Pump Instruction Manual

1. Introduction

This manual provides essential instructions for the safe and effective operation, setup, and maintenance of your Mityvac MV8255 Selectline Dual Vacuum/Pressure Hand Pump. The MV8255 is a versatile tool designed for both vacuum and pressure applications, making it suitable for various automotive diagnostic and service tasks, including brake and clutch bleeding.

The pump features a durable, molded PVC body, ensuring resistance to chemicals and corrosion. Its ergonomic design facilitates single-person operation, enhancing efficiency for both professional technicians and DIY enthusiasts.

Figure 1: The Mityvac MV8255 hand pump, featuring a clear pressure/vacuum gauge for precise readings.

2. Product Overview

The Mityvac MV8255 is engineered to provide reliable vacuum and pressure generation for a wide range of automotive applications. Key features include:

• Dual Functionality: Capable of generating both vacuum (up to 25" Hg) and pressure (up to 30 psi).
• Integrated Gauge: A compound gauge allows continuous monitoring of vacuum or pressure levels, crucial for accurate diagnostics.
• Durable Construction: Constructed from molded, chemical-resistant PVC for extended tool life.
• Ergonomic Design: Optimized for comfortable, single-handed operation.
• Field Serviceable: Designed for easy maintenance and repair of internal components.

Figure 2: The integrated compound gauge of the MV8255, displaying measurements for both vacuum and pressure.

3. Setup

The MV8255 pump is sold without accessories. For most applications, you will need to acquire appropriate hoses, adapters, and fluid reservoirs, often available in Mityvac hand pump accessory kits.

3.1 Connecting Hoses and Adapters

1. Identify the appropriate hose and adapter for your specific application (e.g., brake bleeder screw, vacuum line).
2. Connect one end of the hose to the desired port on the MV8255 pump. The pump has two ports: one for vacuum and one for pressure, typically indicated by markings or the position of the mode selector switch.
3. Connect the other end of the hose, with the appropriate adapter, to the component you intend to test or service.

3.2 Mode Selection

The MV8255 features a selector switch to alternate between vacuum and pressure modes. Locate the switch on the pump body and move it to the desired setting (Vacuum or Pressure) before operation.

Figure 3: The selector switch on the MV8255, allowing users to easily alternate between vacuum and pressure modes.

4. Operating Instructions

4.1 General Operation

1. Ensure all connections are secure and the mode selector is set correctly.
2. Squeeze and release the pump handle repeatedly to generate the desired vacuum or pressure.
3. Monitor the integrated gauge for real-time readings.
4. To release vacuum or pressure, consult your specific application's procedure or slowly disconnect the hose from the pump.

4.2 Brake and Clutch Bleeding

The MV8255 is effective for one-person brake and clutch bleeding. Always refer to your vehicle's service manual for specific bleeding procedures.

1. Connect the pump to the bleeder screw using an appropriate hose and adapter. Ensure a fluid collection reservoir is in-line to prevent fluid from entering the pump.
2. Set the pump to Vacuum mode.
3. Apply vacuum by squeezing the pump handle. Maintain a steady vacuum level (e.g., 15-20 inHg) as recommended by your vehicle's manual.
4. Open the bleeder screw. Observe the fluid and air bubbles flowing into the collection reservoir.
5. Close the bleeder screw before releasing the vacuum on the pump.
6. Repeat the process until no air bubbles are visible in the fluid.
7. Regularly check and refill the master cylinder reservoir to prevent air from entering the system.

Figure 4: Demonstration of the MV8255 hand pump connected to a vehicle's brake system for bleeding.

Figure 5: A closer view of the MV8255 in action, highlighting the gauge and the transparent hose for fluid observation.

4.3 Diagnostic Testing

The MV8255 can be used to test various automotive components requiring vacuum or pressure, such as:

• Turbocharger Waste Gates: Apply pressure to test for proper function and accuracy.
• Cooling Systems: Apply pressure to identify leaks that could lead to overheating.
• Vacuum-Operated Components: Test actuators, sensors, and other parts for proper vacuum response.

Important Safety Note: The MV8255 is designed to pump air only. Fluids should never be drawn directly into the pump to prevent damage to internal seals. Always use an in-line reservoir for fluid collection or dispensing.

5. Maintenance

Regular maintenance ensures the longevity and reliable performance of your Mityvac MV8255 pump.

• Cleaning: After each use, wipe the pump exterior with a clean, dry cloth. Avoid using harsh chemicals that may damage the PVC body.
• Seal Inspection: Periodically inspect the internal seals and O-rings for wear or damage. The MV8255 is field serviceable, meaning replacement seal kits are available. Refer to Mityvac's official resources for detailed service instructions.
• Storage: Store the pump in a clean, dry environment, away from extreme temperatures and direct sunlight.
• Handle Care: While durable, avoid excessive force on the pump handle to prevent potential stress fractures.

6. Troubleshooting

If you encounter issues with your MV8255 pump, consider the following:

7. Specifications

8. Warranty and Support

For warranty information, technical support, or to inquire about replacement parts and accessories, please contact Mityvac customer service directly. Refer to the official Mityvac website or product packaging for the most current contact details.