need helps on 90 brake problem

[kgriggs75]

Ok customer bring in a 1990 cadillac seville with 144k with 4 wheel disk no abs.


the complaint is the car doesn't stop like before. he had taken it to another shop 5 months ago for new pads. upon leaving he noticed it would barely stop. he took it back and the guy say the engine was not making enough vacuum for the booster because the engine was bad. the master cylinder was replaced shortly before due to a leak and it stopped fine between then and the pad change.


upon first inspection i notice the connector for the brake light on the master was disconnected. So far i have bled the brakes which helped some as there was air in the lines. the light still on and the car was still not stopping well. I then did a full system flush and bleed as well as checked all lines and calipers for leaks damage and signs of the rubber lines collapsing in side. I bled the brakes per Cadillac service manual. I visually observed that all for calipers were moving when the brake was applied, and that they were not binding up any. there is 2 and one half inches of brake pedal travel engine running and 2 inches engine off. the light still on and brakes still not up to snuff.

I also checked for codes none were there, the engine runs a bit rough and vacuum is at 14 the booster itself tested ok, all vacuum operated devices are working. I believe that the car has an intake leak but I am not convinced that this is the cause of the problem. the other shop wanted to rebuild the engine to fix this apparently. thanks again for the help.

[snshddog]

I had one of those with a bad check valve on the master. Run it then when its shut off check for vacume in the booster. That would not keep the light on but it's worth a shot.

[maxwedge]

Low vacuum such as that will affect brake boost, improperly machined rotors can cause excessive pedal effort.