Q: my son replaced a brake line on my cadillac deville 2001 but he cant seem to bleed them properly

Sometimes replacing a brake line or hose can cause the brake system to become air-bound. Try gravity bleeding the brake system first. With the brake fluid reservoir cap removed and the brake fluid level correct, loosen the bleeder screw at the wheel that corresponds to which brake line or hose was replaced. DO NOT TOUCH the brake pedal while the master cylinder reservoir cap is removed. Allow gravity and atmospheric pressure to get the brake fluid to drip from the loosened bleeder screw. This can take just a few minutes or several minutes but be sure the brake fluid level does not fall below minimum or you will just be introducing more air into the brake system.

Once the brake fluid begins to flow at the loosened bleeder screw, re tighten it, top off the brake fluid, and reinstall the brake reservoir cap. If a vacuum brake bleeder is not available, then grab a friend to help manually bleed the brakes. Start at the right rear wheel, then left rear, then right front, then finally the left front wheel. Have your friend pump the brake pedal 2-3 times, then hold the pedal.When you loosen the bleeder screw, the brake pedal should drop and fluid should squirt out. Make sure your friend does not push the brake pedal to the floor when this happens. I usually place my left foot under the pedal to make sure that does not happen. Once fluid comes out, tighten the screw, then have your friend release the brake pedal and pump it again. Bleed each wheel 2-3 times or until air stops coming out. Be sure to frequently check the brake fluid level and do not let it get too low.

If this does not get the brakes properly bled, then it might be best to have a certified technician bleed and flush the brake system to make the vehicle safe to drive.