Convertible Top Pump, Cylinders & Hoses Installation or Replacement

Convertible Top & Weatherstrip Specialists 

Overview

This guide provides step-by-step instructions for installing or replacing the convertible top pump, cylinders, and hoses in 1968-1972 GM A-Body vehicles, including Chevelle, Malibu, SS, Skylark, Gran Sport, Tempest, LeMans, GTO, Cutlass, Cutlass Supreme, and 442 models. Disclaimer: This is an advanced automotive project. If you’re not comfortable with hydraulic systems, professional installation is recommended.

Required Tools and Supplies

·         Convertible top pump kit (includes motor, hoses, cylinders) — topsdown.com

·         Automatic Transmission Fluid (ATF)

·         Shop towels or rags

·         Container for old hydraulic fluid

·         Socket and wrench sets

·         Screwdriver set

·         Wire cutters and connectors (if needed)

·         Turkey baster or syringe

·         Pry bar or body panel tool

·         Assistant to help

Pre-Installation Steps

·         Lower the top completely to relieve pressure and improve access.

·         Disconnect the negative battery terminal to prevent electrical shorts.

·         Locate the pump, typically behind the rear seat on the driver’s side.

·         Remove rear seat and interior quarter panels for access to the pump, cylinders, and hoses.

Removing Pump and Hoses

·         Use a container to catch old fluid. Remove as much as possible from the pump reservoir with a turkey baster or syringe.

·         Unplug the pump motor’s electrical connection.

·         Disconnect the two hydraulic lines from the pump using an open-end wrench, keeping rags handy for any leaks.

·         Unbolt and lift out the motor and pump assembly.

Removing Cylinders and Lines

·         With the top down, remove bolts and clips securing the hydraulic cylinders to the top frame and body.

·         Disconnect hoses from cylinders and pull them out, noting they typically run under the rear package tray.

·         Take care to avoid spills, as old hydraulic fluid can be messy.

Installation and System Bleeding

·         Install the new hydraulic cylinders as outlined, using provided shoulder bolts and bushings.

·         Route new hoses from the cylinders to the pump, ensuring hoses aren’t pinched or kinked by moving parts.

·         Mount the new pump assembly, following the kit's instructions for the three-point mounting system. Ensure it has the correct electrical plug for your vehicle.

·         Connect hoses to the pump fittings, using thread tape to prevent leaks.

·         Reconnect the pump’s electrical wiring.

·         Fill the pump reservoir about three-quarters full with ATF. Leave the plug off initially.

·         Bleed the system by reconnecting the battery and cycling the top up and down, ideally with a friend helping.

·         Monitor fluid level and add as needed. Watch for bubbles in the reservoir as air exits the system.

·         Repeat until the top operates smoothly and no bubbles remain.

·         With the top down, top off fluid to about ¼ inch below the seam. Replace, but don’t overtighten, the reservoir plug.

Final Steps

·         Clean up excess fluid from the pump, reservoir, and panels.

·         Reinstall the interior quarter panels and rear seat.

·         Test the convertible top several times to ensure smooth, quiet operation and check for leaks.