BRAKE PROBLEM on 1994 Honda Accord

HELLO I HAVE SERIOUS BRAKE PROBLEM WITH MY 1994 HONDA ACCORD WHICH IS WHILE DRIVING DAILY THE HYDRAULIC BRAKE SYSTEM TENDS TO BUILD PRESSURE IN THE LINES WHICH CAUSES THE BRAKES TO LOCK UP WHILE DRIVING. I WAS TOLD THAT THE PROPORTIONING VALVE MIGHT BE THE PROBLEM. THANKS FOR THE YOUR HELP

by in Memphis, TN on April 02, 2010
2 answers
ANSWER by , April 02, 2010
Has the brake master cylinder been replaced? If so I suspect the clearance at the brake master cylinder actuating piston to brake booster actuating plunger is insufficient, as the brakes get used a few times the get hot and the clearance becomes less allowing the brakes to drag or even lock up.
ANSWER by , April 03, 2010
This issue can happen when some other fluid other than brake fluid is introduced into the system. Typically automatic transmission fluid is mistakenly put in the master cylinder but I have seen other fluids cause the same symptoms. If the master cylinder has not been replaced then I would look for some type of contamination.