OTC Tools 7853 ABS Brake Proportioning Valve Depressor User Manual

1. Introduction

The OTC Tools 7853 ABS Brake Proportioning Valve Depressor is a specialized tool designed to assist in the bleeding of brake systems on specific vehicles. This tool is essential for properly bleeding brakes on various GM utility vehicles, vans, and pickups equipped with Kelsey Hayes anti-lock brake systems. It also functions effectively on rear-wheel anti-lock brake systems. For vehicles with four-wheel anti-lock systems, using two depressors is recommended for optimal results.

This manual provides comprehensive instructions for the safe and effective use of your OTC 7853 tool. Please read all instructions carefully before use.

2. Safety Information

Always observe the following safety precautions when working with vehicle brake systems:

• Wear appropriate personal protective equipment, including safety glasses and gloves.
• Ensure the vehicle is securely supported on a level surface using jack stands before beginning any work.
• Never work under a vehicle supported only by a jack.
• Brake fluid is corrosive. Avoid contact with skin, eyes, and painted surfaces. In case of contact, rinse immediately with plenty of water.
• Dispose of used brake fluid according to local environmental regulations.
• If you are unfamiliar with brake system maintenance, seek assistance from a qualified automotive technician.

3. Product Overview

Image: The OTC Tools 7853 ABS Brake Proportioning Valve Depressor. This image shows the compact tool, featuring a blue plastic handle and a metal depressor fork with an adjustable screw, designed to hold open a proportioning valve during brake bleeding.

The OTC 7853 is a compact, specialized tool designed to depress the proportioning valve rod in specific ABS brake systems. This action prevents the valve from closing prematurely during the brake bleeding process, ensuring proper fluid flow and air removal.

What's in the Box:

• 1 x OTC Tools 7853 ABS Brake Proportioning Valve Depressor

4. Setup

Before using the OTC 7853, ensure your vehicle's brake system is compatible with this tool. The 7853 is specifically designed for GM utility vehicles, vans, and pickups with Kelsey Hayes anti-lock brake systems, and rear-wheel anti-lock brakes.

Installation Steps:

1. Locate the Proportioning Valve: Identify the proportioning valve on your vehicle's ABS unit. This is typically found near the master cylinder or along the brake lines. It often has a rubber dust cap covering the port where the depressor is inserted.
2. Prepare the Port: Remove any dust caps or covers from the proportioning valve port.
3. Insert the Depressor: Carefully insert the fork end of the OTC 7853 tool into the proportioning valve port. The tool is designed to block the proportioning valve's rod from opening fully, or to hold it in a specific position.
4. Secure the Depressor: Ensure the tool is firmly seated and holding the valve rod as intended. For some applications, the tool may need to be adjusted or secured to maintain its position.

Note on Compatibility: While effective for its intended applications, some users have reported that this tool may require modification to fit certain non-specified vehicles, such as older Jeep models. Always verify fitment for your specific vehicle before attempting to use the tool. Modifications are performed at the user's own risk and are not endorsed by the manufacturer.

5. Operating Instructions (Brake Bleeding Procedure)

The OTC 7853 is used in conjunction with a standard brake bleeding procedure. A two-person method is generally recommended for best results.

Recommended Brake Bleeding Sequence:

Always bleed the brake system starting with the wheel furthest from the master cylinder and working towards the closest. A common sequence is:

1. Passenger Rear Wheel
2. Driver Rear Wheel
3. Front Passenger Wheel
4. Front Driver Wheel

Step-by-Step Bleeding Process (Two-Person Method):

1. Prepare the System: Ensure the master cylinder reservoir is full of fresh brake fluid. Keep it topped off throughout the process to prevent air from entering the system.
2. Install Depressor: Insert the OTC 7853 into the proportioning valve as described in the Setup section. If working on a four-wheel ABS system, install two depressors if applicable.
3. Connect Bleeder Hose: Attach a clear hose to the bleeder screw of the first wheel cylinder/caliper (e.g., passenger rear). Place the other end of the hose into a container partially filled with clean brake fluid.
4. Initiate Pedal Press: Have one person slowly and steadily press the brake pedal down.
5. Open Bleeder Screw: While the pedal is held down, the second person should open the bleeder screw approximately a quarter to half turn. Observe fluid and air bubbles flowing into the container.
6. Close Bleeder Screw: Before the brake pedal reaches the floor, close the bleeder screw.
7. Release Pedal: Once the bleeder screw is closed, the person inside the vehicle can slowly release the brake pedal.
8. Repeat: Wait approximately 15 seconds, then repeat steps 4-7 for the same wheel. This process may need to be repeated 5-10 times per wheel until no air bubbles are visible in the fluid flowing through the hose.
9. Move to Next Wheel: Once the first wheel is bled, move to the next wheel in the sequence and repeat the process.
10. Final Check: After bleeding all wheels, remove the OTC 7853 depressor(s). Check the brake pedal for firmness. If the pedal feels spongy, repeat the entire bleeding process. Top off the master cylinder reservoir to the appropriate level.

Using a Vacuum Pump: If using a vacuum pump for bleeding, follow the pump manufacturer's instructions, but maintain the same wheel bleeding sequence and ensure the OTC 7853 is installed to prevent the proportioning valve from closing.

6. Maintenance

Proper maintenance ensures the longevity and reliable performance of your OTC 7853 tool.

• Cleaning: After each use, wipe the tool clean with a cloth to remove any brake fluid residue or grime. Brake fluid can be corrosive to certain materials over time.
• Inspection: Periodically inspect the tool for any signs of damage, bending, or excessive wear. Ensure the adjustable screw (if present) operates smoothly.
• Storage: Store the tool in a clean, dry place away from direct sunlight and extreme temperatures.

7. Troubleshooting

Common Issues and Solutions:

• Tool Does Not Fit the Proportioning Valve:
  • Cause: The vehicle's proportioning valve may not be a compatible Kelsey Hayes or GM type, or it may be an older design (e.g., some vintage Jeeps) that requires a different tool or modification.
  • Solution: Verify your vehicle's specific brake system type and proportioning valve design. Consult your vehicle's service manual. If the tool is confirmed incompatible, do not force it. Seek an alternative tool or professional advice.
• Brake Pedal Remains Spongy After Bleeding:
  • Cause: Air may still be trapped in the brake lines, the bleeding procedure was not followed correctly, or there may be another issue with the brake system (e.g., master cylinder, caliper, or line leak).
  • Solution: Re-verify that the OTC 7853 was correctly installed and remained in place throughout the bleeding process. Carefully repeat the entire bleeding procedure, ensuring no air enters the master cylinder and that bleeder screws are tightened before the pedal is released. If the issue persists, inspect the entire brake system for leaks or component failures.

8. Specifications

9. Warranty and Support

For information regarding warranty coverage, technical support, or replacement parts for your OTC Tools 7853 ABS Brake Proportioning Valve Depressor, please contact OTC customer service directly. Refer to the official OTC website or product packaging for the most current contact information.

OTC Customer Service: Please visit the official OTC website or refer to your product packaging for contact details.