Oldsmobile/Buick Repair/1999 Olds Alero
QUESTION: How do I reset the proportional valve on my Alero. It has the 3.4 Liter 6 cylinder with 4 speed auto transmission. I purchased the car with no engine and it had not run for about 4 years. I have most of the problems fixed but I only get brake fluid from the front right and rear left brakes when I bleed them. A friend suggested I need to reset the proportional valve. I know where it is located below the battery but have not seen it yet. Thanks for any assistance you can provide..
ANSWER: HI FRANK, THIS CAR HAS A BI-DIRECTIONAL BRAKING SYSTEM. THIS MEANS THE MASTER CYLINDER FEEDS THE LF TO RR AND THEN RF TO LR. SO IF THE PROPORTIONAL VALVE WAS TO BLAME YOU WOULD NOT GET ANY FLUID TO THE REAR AT ALL. YOU SAID YOU DO GET FLUID TO THE LR..THE PROBLEM COULD BE FROM A BAD MASTER CYLINDER..TAKE THE 2 LINES OFF THE MASTER CYLINDER ONE AT A TIME AND TRY TO BLEED THE MASTER CYLINDER BY PUTTING YOUR FINGER OVER THE LINE PORT WHEN THE LINE IS REMOVED. NOW PUSH THE PEDAL DOWN AND SEE IF ANY FLUID COMES OUT OF EACH OF THE MASTER CYLINDER LINE PORT. . IF SO MORE THEN LIKEY THERE IS ALOT OF AIR TRAPEED IN THE LINES..IF ONLY ONE SIDE OF THE MASTER CYLINDER HAS FLUID.THE MASTER CYLINDER IS BAD..REPLACE IT. IF FLUID COMES OUT BOTH PORTS THEN I WOULD LIKE YOU TO GO TO THE RIGHT REAR AND LOOSEN THE BLEEDER SCREW AND HAVE SOME ONE JUST PUMP THE BRAKES UP AND DOWN WHILE YOU HOLD YOUR FINGER OVER THE BLEED SCREW. DO NOT STOP PUMPING,JUST PUMP AWAY FOR 2 TO 3 MINUTES IF NEED BE. MAKE SURE THE MASTER CYLINDER IS FULL OF FLUID AND ALL THE BLEEDER SCREWS ARE NOT PLUGGED WITH DIRT AND RUST. YOU SHOULD START TO GET FLUID OUT OF THE BLEED SCREW LIKE THIS. ONCE IT STARTS TO COME OUT THEN TIGHTEN THE BLEED SCREW AND BLEED THE BRAKES AS YOU NORMALY WOULD..LET ME KNOW HOW THIS GOES ,GOOD LUCK TOM
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QUESTION: Thanks for the good information. I first checked the front port of the master cylinder and it seemed to pump fluid as soon as the brake pedal was depressed. I was unable to remove the line from the rear port, as it seemed to be held by an internal spring. I did pull it outward about an inch and it also pumped fluid after the pedal was depressed. We next did the right rear and soon we were getting a full stream there. We then bled each brake twice and we got a full stream and no air from any. The problem now, is that the brake pedal still goes all the way to the floor when it is depressed. Any idea of the next step to correct this? Thanks in advance..
HI FRANK,,YOU STILL HAVE AIR IN THE LINES,KEEP BLEEDING IT AND HOPEFULLY YOU WILL FIND A BUNCH OF AIR COME OUT AFTER AWHILE..IF HOWEVER YOU CONTINUE BLEEDING ALL THE WHEELS SAY LIKE 8 TIMES PER WHEEL AND ALL FLUID IS GOOD AND NO AIR FOUND..THIS SOUNDS LIKE A BAD MASTER CYLINDER..I DO NOT KNOW OF ANY INTERNAL SPRING IN THE MASTER CYLINDER LINE PORT..THIS MAKES NO SENSE..THE ONLY WAY TO DIAGNOSE FOR SURE IF THE MAS CYL IS BAD IS TO REMOVE THE BRK LINES FROM THE MAS CYL AND INSTALL PLUGS IN THE PORTS AND TRY TO PUSH THE PEDAL DOWN LIKE THIS..IT SHOULD BE VERY HIGH AND HARD..IF THE PEDAL SINKS LIKE THIS THE MAS CYL IS FOR SURE BAD. COULD HAVE A BAD PRIMARY PISTON. YOU CAN BUY THESE FITTINGS AT THE HARDWARE STORE,OR GET 2 SHORT LINES AND WELD THE ENDS SHUT...LET ME KNOW WHAT HAPPENS..TOM