Brake problem 89 Maverick

wont a bust booster give you a hard pedal
cheers

malleerv
you obviously not sure about how a booster operates , the only function
of the booster is to reduce pedal effort ,thats all it does .
sounds like you have air in the system and or adjustment of the rear brakes
mechpete

Roughasguts

Sorry for hi-Jacking mudmav's thread. But what you describe is exactly what is happening with my 75 series Troopy. Just arrived home after four weeks in SA all was going well then as we headed for home (Gosford) the brake peddle started to travel further and further untill it eventually nearly reached the floor.

One pump would bring it back to a firm brake for awhile then after a few minutes back down to the floor again.

Can you offer any advice on what may be causing this or where I should start looking?

Thanks in advance

Michael

Michael

Is your master cylinder reservoir still full? I would not be surprised if you have slowly run out of fluid and air is starting to get in through the cylinder. This is almost always caused by a leak somewhere in the system or in rare cases it can happen over a very long period by not topping up the cylinder as the brake linings slowly wear out.

Try pumping the pedal then leave your foot lightly on it and wait. If you feel the pedal slowly sinking down under your foot, you may have a leak at the wheel or in the lines but it is more likely to be the fluid going back past leaking seals in the master cylinder. This used to show up in the old non boosted systems by fluid running down the firewall under the cylinder or inside under the carpet. With a combined booster and master cylinder, it is possible for the fluid to leak back into the booster and not be visible from outside.

To check this start by pulling the check valve out of the booster. This is usually a large plastic valve on the end of the vacuum hose running from the engine manifold to the booster. It just sits there in a rubber grommet in most cars and usually comes out easily. Get a stiff piece of string and poke it well into the booster. If it comes out with brake fluid on it you have a leaking master cylinder. It will have to be removed, dismantled and inspected. If the bore looks ok you can put a new seal kit in it. If not then you need a new cylinder.

Some people hear have mentioned boosters but they will not cause this problem. There is a simple test you can do at any time though to check a booster. With the engine off, pump the pedal a few times to get rid of any vacuum in the booster. The pedal usually comes up a bit and feels a little harder when you do this. Hold it down firmly and start the engine. The pedal will immediately sink down a little as the booster starts working. Keep your foot on the pedal and turn the engine off. The pedal should stay there. If it tries to push your foot back up, the previously mentioned check valve is leaking. This valve is designed to hold sufficient vacuum in the booster for two or three applications of the brakes should the engine suddenly cut out. This enables you to stop the car without having to stand on the pedal due to loss of booster assistance.

Could be a rear brake lining worn way to far! so then it needs more fluid to hit the drum several pumps! Because the shoes are no where near the drum in the rest position to start with.
Hence why it needs more pumps, Holds but when the shoes come back to rest (outside adjustment specs) they have pushed a lot of fluid 3 pumps worth back in to the master cylinder.

So adjust pads and or replace if there close to worn out.
Cheers.

Splits and Roughasguts

Thanks for the answers very much appreciated, I will start investigating this week.

Michael