How to Bleed Brakes and Install Demco Hydraulic Brake Actuator with Electric Lockout DM8164311

Updated 02/10/2020 | Published 02/08/2020

Question:

I am replacing a 12,000 hitch with yours DM8164311/16,000 lb. I have a tandem trailer with rear only disc brakes. The boat weighs 12,000 lbs. I never received any installation instructions. I am concerned with the electrical connecting and how to purge the lines. I have looked on U tube and have an idea. I would like some instructions for this specific model please. I can down load the instructions if you can email them or what ever you think is best. Thank you.

asked by: Richard C

Helpful Expert Reply:

The solenoid on the Demco Hydraulic Brake Actuator w Drop and Electric Lockout # DM8164311 will have two wires coming out of it, a ground wire and a power wire. You'll need to connect he power wire to the reverse circuit on the trailer connector. To ground the solenoid, you could either ground the wire to chassis (recomended) or connect to an existing solid ground connection. When your vehicle's in reverse, this solenoid will ensure that that hydraulic actuator does not activate your trailer brakes, allowing you to back up your trailer.

Page 10 of the operator manual I attached walks through the steps of bleeding the brakes on the DM8164311 brake actuator. The steps provided are as follows:

1. Elevate tongue on trailer 4-6 inches.

2. Loosen or remove two 5/16” bolts that hold the lever guide and flat emergency lever spring. Remove master cylinder fill cap.

3. Using short strokes, pull forward on emergency lever, pumping master cylinder until brake fluid in master cylinder reservoir stops bubbling.

4. Attach a bleeder hose to a bleeder valve on one of the wheels (starting at wheel farthest from master cylinder ) and submerge other end into a transparent container partially filled with brake fluid to prevent possible splashing from container.

5. Loosen bleeder valve one turn and while watching fluid in container, use emergency lever to pump fluid as long as bubbles continue to leave submerged hose. When bubbles stop, close bleeder valve, move to next wheel and repeat until all brakes are bled. ( Note: Check master cylinder often (every 4-5 strokes) and refill above half full as needed).

6. Refill master cylinder and securely attach cap. Reinstall emergency lever spring, lever guide, lock washers and 5/16” hex head bolts. When tightening the bolts, make sure the lever moves freely in the groove in the guide.

I've attached an installation video on a similar actuator with electric lockout for you as well since the steps are basically the same.