Mazda b2500
There are 3 reasons for this. 1) it could be that the brake reservoir is low. 2) the brakes may have a leak. 3) it could be that the lines have air in them. I suggest that the car be sent to a mechanic who will bleed the brakes properly. But if you can do it yourself, then you need a helper to do the pumping while you bleed the brakes. It a big job and requires absolutely cleanliness, as dust and dirt are the dreaded when it comes to bleeding brakes. Bleeding nipples need to be cleaned of any dirt or dust before doing the bleeding. Attach a 1 and half foot of flexible clear surgical tube to the nipple. The reason it must be a clear type of plastic or rubber is because you must be able to see air bubbles escaping out in the brake cylinder/servo as your helper pumps the pedal slowly. You must use the right spanner with a ring end to turn the nipple so it stays always on the nipple and not falling off. You need to communicate with the helper all the times. You need to ask him to pump down the pedal and observe the fluid reservoir and top if up at each 4-5 pumps. On the 5th pump you turn the nipple such at he pumps, not as he lifts the pedal up. Always shut the nipple when the pedal is on its way down, not on its way up. The resulting (dirty and probably bubbly brake fluid should be collected in a large jar and not used again. The bleeding should be complete when there are no air bubbles and the fluid looks like new. Before you turn the nipple shut, you must do one more pedal down bleeding. As the pedal goes done, or as the fluid slowly flows in the plastic tube, you immediately lock the nipple shut at midway to the brake pedal going down. Make sure that during this process the plastic or rubber tube doesn't slip out. If you think it might do so, then tie a plastic covered wire that is used to tie cables from a... say a DVD recorder; you know, those short pieced of black plastic covered wires found tying the cables with on these electronic appliances. Make sure the jar collecting the waste fluid is large and wide so it doesn't topple over. When bleeding the brakes, it is recommended to start at the rear first, with the car jacked up high enough for you to work underneath, and also to stop air bubbles from going back to the reservoir. Find the longest line at the back, from the splitting block to the brakes, then do the other one. After you did the rear brakes. lower the bar and raise the front high enough to work under it. A word of advice, never work under the front of the car raised with a jack alone. You either use proper stands or drive the car up a pair of ramps. The car is really heavy at the front because of the engine and can easily crush you if your jack alone fails, or it might slip off it's supporting points. Start bleeding the disc brakes like you bleed the drums, doing the longest from the reservoir first. And just remember, 4 pumps of pedal down, check the reservoir. 4 pumps again, check the reservoir. Never let it run low. If it does, you have to start all over again. That's why you need a helper to pump and keep an eyes on the reservoir. Both remember the 4 pumps, then check, them 4 pump again, then check. It takes time. So, be safe and good luck.
