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1997 Geo Tracker Bench Bleed a Master Cylinder

The Geo Tracker is a mini SUV that was manufactured from 1989 to 1997. When you need to replace your Geo Tracker's brake master cylinder, you must bench bleed the new cylinder before installing it. A new master cylinder has air trapped inside that gets pumped into your brake lines, if you don't bleed it out. These steps only take about 10 minutes and apply to any year Geo Tracker.

Tools Used: Replacement brake master cylinder (varies between models and years), Bench bleed kit (may come with the cylinder), Bench vise or clamp-on vise, Bottle of DOT 3 brake fluid, Philips head screwdriver

Bench Bleed a Master Cylinder

Remove the old brake master cylinder from your Geo Tracker. Look for the brake fluid reservoir, since it's attached to the top of the cylinder, on the driver's side of the engine bay toward the firewall. If you're planning on reusing the old brake fluid reservoir, remove it from the cylinder and clean it out well. Make sure to dry it off completely before installing it into your new brake master cylinder.

Clamp the new Geo Tracker brake master cylinder into a bench vise. If you don't have one of these, you can use a clamp-on vise to secure the cylinder to a work table. Make sure the cylinder is level.

Find the two fittings that came with your bench bleed kit and screw them into the outlet holes on the master cylinder. Depending on your Tracker's model year, the outlets could be on the sides or the top of the cylinder. Insert the two hoses from the kit into the fittings.

Bend the hoses up, so the ends sit inside the Geo Tracker's brake fluid reservoir. You may need to cut them to the right length; they should stick about halfway down into the reservoir.

Pour fresh DOT 3 brake fluid into the reservoir up to the maximum fill line. The tubing will be submersed in the fluid, creating a hydraulic system. Be careful around your SUV when pouring the brake fluid; if any fluid spills on the body, clean it up right away using an old towel with soap and water to prevent paint damage.

Get your Philips screwdriver and insert it into the new brake master cylinder. Firmly push the screwdriver against the piston to start pumping the fluid through the unit.

Keep an eye out for air bubbles going through the system. You'll be able to see them coming out into the brake fluid. If you use clear hoses, this allows you to see the bubbles much easier; however, some brake bleed kits come with black hoses, so you may want to buy clear ones instead.

Pump the piston on the master cylinder until you no longer see bubbles coming out. Leave the hoses where they are and carefully unclamp the vise. Remove the cylinder from the vise and it's ready to install in your Geo Tracker.

Tips & Warnings

Avoid letting the reservoir run dry, since pumping the cylinder without brake fluid will put air into the system and you'll have to start over. It's unlikely that the fluid will get low, if you put the proper amount in the reservoir to begin with.

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