Air in the brakes.

2001 dodge caravan. The brake pedal went to the floor, so I replaced the master cylinder and bled the system. I replace the rotors and pads on the front and again after 3 days the pedal went to the floor. I bled the system again and found that just the left front has air in the line and each time I bleed this line it has air bubbles in the fluid. Several mechanics have never heard of this problem and I would be open to suggestions as what is causing the ait to get into this line. There is no leak in the system and the fluid does not go down between bleedings. I have bled the system about 6 times now and it lasts for about 3 days of moderate driving. Is this in any way related to the ABS??
Thanks
Al:banghead:

2001 dodge caravan. The brake pedal went to the floor, so I replaced the master cylinder and bled the system. I replace the rotors and pads on the front and again after 3 days the pedal went to the floor. I bled the system again and found that just the left front has air in the line and each time I bleed this line it has air bubbles in the fluid. Several mechanics have never heard of this problem and I would be open to suggestions as what is causing the ait to get into this line. There is no leak in the system and the fluid does not go down between bleedings. I have bled the system about 6 times now and it lasts for about 3 days of moderate driving. Is this in any way related to the ABS??
Thanks
Al:banghead:

Welcome on your first post on AF.
Yes that may be the problem.
With Teves Mark 20 ABS brakes.
And you let/get air into the ABS system
My repair info says you need a ABS capable scanner with the ABS bleeder setup on it to bleed the brakes.
If all else fails take it to a dealer or good repair shop with the ABS scanner with the beeding set up.

You have a leak in your front left or rear right brake line somewhere, check the front rubber brake hose for cracks. Check the metal brake line for leaky connections where there are nuts on the flared fittings, and rust on any retaining brackets. Check the front caliper piston seals, and the right rear piston inside the drum. Check the brake line welded connection on area right above rear axle.

You have a leak in your front left or rear right brake line somewhere, check the front rubber brake hose for cracks. Check the metal brake line for leaky connections where there are nuts on the flared fittings, and rust on any retaining brackets. Check the front caliper piston seals, and the right rear piston inside the drum. Check the brake line welded connection on area right above rear axle.
Thanks

Thanks for the suggestions but the problem is that there is air in the line only at the left front no matter how much I bleed it, the fluid comes out milky looking only at the left front, there is no sign of a leak in any of the connections and lines.