Here is what I would do. First flush out the system with fresh Castrol GTLMA DOT 4 brake fluid. If that doesn't help then disconnect and plug the vacuum line to the brake booster and go for a drive. If that does it you need a new or rebuilt booster. BTW look inside the vacuum hose from the booster and if it is wet with brake fluid it is dead anyway. My first guess is that the fluid is so contaminated with water that when it heats up and boils it is locking the brakes. If the system is as bad as I think it might be you will soon be doing a complete rebuild of all of the calipers and master cylinder anyway. BTW if it is a 5-speed flush the clutch master and slave too. This should be done every 2 years as per the owner's manual (flushing that is, not rebuilding the system). A brake shop I know says about every 6 months or so he has a similar complaint from a customer. It usually turns out the customer or the gas station put WINDSHIELD WASHER FLUID into the brake master cylinder resovoir!!!!! David Teitelbaum vin 10757 --- In dmcnews@xxxx, "Payne" <bpayne@xxxx> wrote: > I must say this is the most frustrating problem I've had with my car yet. > If I drive it for any longer than five minutes, the brakes will lock up and > the pedal get's incredibly stiff with no travel at all. It seems to be > mostly the front calipers and they will eventually release after they cool > down. The brake fluid does look rather old and I know it needs to be > flushed, but would that cause them to lock up? I've driven it every day for > a year and it happened rather suddenly. > > Thanks for your help! > > payne