[66seafoam]

Recently bought a 66 sea foam green impala. Spotless interior and all original. the 327 runs great, but we're having problem with the brakes. I checked the fluid reservoir and its full. You can push the pedal all the way down with out really any brakes engaging but if you pump the pedal, the brakes will begin to engage enough to stop it. I wouldn't dare drive it as it is, and am getting frustrated because I recently had to scrap my other vehicle to transmission problems. Was wondering if any one cold put in their 2 cents about it, if its the drums or hydraulic or line or something problem. This is my first classic car so I am unfamiliar with vintage brakes. Thank you!

 

[12ltz]

Could be master cylinder but check for air in brake lines and bleed system.
Check wheel cylinders to make sure they are operating and get a car manual for your year car that always helped me.
Also Welcome and post some pic of car

 

[Dadstoy]

I agree , could be a bad master cyl. I would do a brake inspection. Check all brake lines and hoses. Pull the wheels and drums and check everything. Might consider upgrading to a double reserver master cyl.

 

[jeffs409]

master cylinder

First look around all wheels and see if you can find any leaks. If you cannot, most likely it will go like this. If you can pump it up and keep pressure on the peddle and it doesn't go down, it's probably just a bleed job. If you pump it up and it holds and then goes down, or doesn't pump at all, it's most likely the master cylinder. Of course there are other issues to look at. You could have frozen wheel cylinders or leaking, but that is why I said to look for leaks at all four wheels. And you could have a leak in the system. Something else to keep in mind. How old is that fluid? I believe the dot 3 and 4 is hydroscopic ( absorbs water ) and that is also a big problem. Try the pump test and get back to us. This should be very straight forward and easy to fix.

Jeff

 

[66seafoam]

I attached a picture also. I just tried what you suggested. When I pump the brakes, they will engage normally and then when I added a lot more pressure while they were engaged, the pedal went all the way down to the floor. From what I can tell there are no leaks, the ground under the car is slightly wet, but we also have sprinkler systems in our yard, so I pulled it forward and will check in a few hours to see if the liquid is from the brake lines. The master cylinder is still full of fluid, so hopefully its not a leak in the line. Before I knew if fluid was the problem, is purchased DOT 5 brake fluid so If I need to drain the fluid and replace it I believe I've got the right stuff. I'm not sure what DOT # fluid is in there now, I just purchased it less than a month ago and didn't ask the owner (he didn't really speak English).

 

[jeffs409]

Dot 5

Dot 5 is not the right fluid for that car. Dot 5 doesn't mix with 3 and 4. Dot 5 is a silcone based fluid. For some reason I cannot remember if you can transfer over to 5 but you would need to flush that system well. And you would not ever want to add 3&4 to a 5 system as it's corrosive and will eat up the seals. It sound like by pumping it up and then while holding the peddle it goes down, that it's most likely the master cylinder if you don't see any leaks.

Jeff

 

[MixedImpala04]

I have had an issue like this before, brand new booster but the diaphram in the booster was bad. Flush and bleed the breaks really well.

 

[66seafoam]

Thank you very much for the help, I think I'm going to go ahead an replace the master cylinder. Is this what I would want to order or something similar?
1962-1966 Chevrolet Impala Brake Master Cylinder - Centric 130.62013 - Centric Premium, OE replacement

And then how would I go about replacing it...just a quick overview or something and what DOT# fluid would you recommend?
Thank you very much, I appreciate the advice and expertise!