QuestionQUESTION: Hi,I have a '65 T-Bird and when I push the brake pedal down it will not come back up by itself,I have to lift it back up with my foot.Could this be the Brake Booster?
Any help would be great.
Thanks David
ANSWER: Hi David:
Yes. I think you have discovered the problem. Assuming it just not a sticky brake pedal linkage. When you hit the brake pedal, the pedal rod cracks open a valve, allowing air to enter the booster on one side of the diaphragm while sealing off the vacuum. This increases pressure on that side of the diaphragm so that it helps to push the rod, which in turn pushes the piston in the master cylinder.
As the brake pedal is released, the valve seals off the outside air supply while reopening the vacuum valve. This restores vacuum to both sides of the diaphragm, allowing your brake pedal to return to its original position.
That valve is not working correctly. before buying a new Booster, you make want to make you the value is just getting stuck open due to rust or lack of lubrication. Hope this helps.
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QUESTION: Great Info Sir,Can I check it myself to see if the valve is just getting stuck?...and also is it a easy thing to replace by myself.I am no mechanic but I have some knowlege of cars..
ANSWER: Hi Again David:
Thanks for the feedback. There is one other little things that slipped my mind about your problem. Although rare, but on a car your age, the springs in the master cylinder could be bad. These springs help return the brake pedal as well, so you could really have a bad master cylinder. When you press brake pedal, is it hard or soft and mushy?
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Hi David:
Yes. The valve should have a hose attached to it that runs from the booster to the engine. That is where the vacuum comes from. Remove that hose from the booster and check to see if it is blocked. When you start the car, there should be air blowing from the hose. If not, there is your problem. Make sure the hose isn't just loose, leaking or broken and the the connections are tight.
If everything checks out OK, you most likely you have a bad booster. But check the brake pedal linkage first to make sure it isn't rubbing against something or that the joint doesn't need lubricating.
If all is OK, you have two options. A) replace the entire assembly, the master cylinder and the booster together, or B) replace just the booster. Either way you can do this yourself. Since it is a 65 T-Bird, I'm guessing the master cylinder hasn't been replaced either, so there is a good chance the rings in that will soon go. If you feel any slippage while holding the brake pedal at a light, that's a sure sign the master cylinder rings are going.
So, it's really up to you. First thing is to find the correct replacement. Let me know if I can help further...Vern
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QUESTION: Hi Vern,Did as you say and checked the hose and it is sucking air pretty well but I did notice a air loss from just under the carb,a small air leak and if I put my finger on it it will stop,so I will have to change the gasket under the carb but do you think that would have an effect on the booster?ALso when I change the booster out and Cylnder do I need to bleed it for air like you would on brake lines?
Thanks Again David.
AnswerThe air lost from he carb sounds like a carb fuel/fixture issue. This would not affect your brakes. I would pinpoint the master cylinder springs at this point. I think you have a bad master cylinder that is not returning the pedal as it should after you take your foot off the brakes. That is the primary job of the master cylinder springs. And yes bleeding is required if you change it. You have to bleed the air out of the cylinders as well as the brake lines, so if you plan to do the repair, make sure you bleed the master cylinder before putting it on and then bleed the brake lines afterward.
