I have a 1994 toyaota T100 4x4 that i've just replaced the metal brake lines on. I've bled the brakes, and have good pedal pressure until I statrt the truck, then it gets mushy again. Any ideas?

bleed the spliter vale out uderneath car near back

sounds like the brake master cylinder seals are worn buy a master cylinder kit and get a mechanic to repair it it is a lot cheaper than replacing the whole unit

try bleeding your ABS block first, if that doesn not work could need a master or proportioning vavle. Some scan tools are capable of bleeding the ABS system on some vehicles, and some you have to bleed manually.

ajust rear brakes untill there is only 4 click on the parking brake

If there's no pedal pressure, you've still got air in the brake pipes or you've got an open fluid circuit. Look for leaks, if none they need bleeding again.

You'll need to start bleeding the brake system at the Master cylinder to determine where the problem lies.

The lines coming out of the master cylinder will need to be loosened & bled there, initially you can just do the back ones to identify the problem, but once fixed, the system will have to be bled from the Master cylinder first, then the farthest wheel from it, then next farthest, then next, until you do the drivers wheel last.

This method of bleeding the brakes prevents air from crossing from one line to another, causing air to be left in the system.

Back to bleeding the rear brakes first: As someone pumps up the brake pressure, making sure the resivoir stays full, with the cap on between bleeding, and have the person pressing the pedal to do these thngs.
1. Always move the pedal slowly, pressing and releasing.
2. Never release the pressure on the pedal after bleeding a brake, until the line is tightened, then release slowly to prevent air from getting into the fluid.

You should of course get fluid at the master cylinder when you bleed it (or just replace it), then you'll need to bleed the line at the right rear wheel (first) a few times to get fluid if it's been leaking, then the left rear wheel. If you get pressure but no fluid to the rear and the master cyliinder did have pressure released when you bled it, there is either a restriction in the line itself, or the porportioning valve could be damaged. (unusual for the valve to go bad actually, inspect lines for damage such as being pinched if you're getting pressure but no fluid.

Final test if it hasn't been resolved-remove lines at porportioning valve & make sure fluid is leaving/entering there as it should. If you find it defective, a good replacement can come from a salvage yard, or you can buy them new.

Brake fluid on the floorboard under the dash near the brake pedal=bad Master Cylinder.

good luck

Air in brake lines. Lines may need to be bled or master cylinder may need to be bled. I would start with brake lines.

there is air there somewhere. try manual bleeding the brakes. do the farthest wheel first. if they are calipers all the way around, when you bleed them tap them gently to remove any air that can still be inside the chambers.

robert

Master cylinder is toast.

The brake booster is not the problem. The Master cylinder will need to be bench bled before bleeding the braking system.