To bleed a Mercruiser trim pump, fill the tank, and remove the lines from the trim cylinder and gimbal housing to drain the hoses. You need hydraulic fluid, a flat-head screwdriver, an adjustable wrench, a container and a pair of safety glasses to protect your eyes from splashing fluid.
- Fill the tank
Use the flat-head screwdriver to loosen the screw that is located toward the top-right section of the pump's tank. Use the hydraulic fluid to raise the fluid to the full marker on the tank. Re-tighten the screw.
- Drain the trim cylinder line
Use the adjustable wrench to remove the Up line that is located on the far left side of the trim cylinder. Use the container to hold the line's hose for draining. To drain the hose, push the trim cylinder's Up switch, and allow the hose to drain. Use the adjustable wrench to reattach the line.
- Drain the gimbal housing line
Use the hydraulic fluid to raise the fluid in the tank to the full line again. Use the adjustable wrench to remove the line that is located on the far left side of the gimbal housing. Use the container to hold the gimbal line's hose for draining, and use the adjustable wrench to attach a plug to the now empty gimbal hole. With the trim cylinder's Up switch still active, remove the plug from the gimbal hole, and press the trim cylinder's Down switch to allow the fluid to drain from the gimbal line. Use the adjustable wrench to re-attach the line to the gimbal housing, and use the hydraulic fluid to raise the fluid to the full line.