HELP! Problems with brakes stiffening after 2-3 pumps!
 

Dear enthusiasts,

I'm experiencing stiffening of my brakes after a few pumps. The pedal initally regresses normally but eventually stiffens at the top and the car almost doesn't stop. However, it does not stay stiff for long. It loosens up as I drive on but the problem repeats at every braking interval...

I've a 99 boxster with 68K miles.

Please advise and thanks in advance.

Hydraulic system problems for sure. Bad master cyl. contaminated fluid, bad caliper... If you are brake savy take a look at the fluid first. If not have it flatbedded to a qualified Porsche shop. Don't drive it with jacked up brakes.

This could be a failing brake booster. The prior owner of my 2000 S had the booster replaced on my car about a year ago at around 65,000 miles. The issue was a hard brake pedal and difficulty stopping.

Loss of vacuum
 

The brake booster relies on engine vacuum to operate correctly. There would be a fleixible hose between the inlet manifold and the pipe that runs along the body
to the booster. Over time
(and the car is ten years old) the flexible hoses becomes
very soft and perished or flakes of on the inside closes up under vacuum and reduces the amount of vacuum flow to the booster paticularly if you pump the pedal. There is also a non return valve in the system to maintain maximum vacuum in the booster when the car is being driven hard and there is very little vacuum in the inlet manifold. Check ALL flexible hoses, non return valve and the fitting on the inlet manifold for blockages. Another test is to remove the hose off the booster with the enine idling and check the flow. It will make the engine run a little rough if it is sucking in fresh air but if it is blocked it probably will not make much difference.
Let me know how you go, remember do the SIMPLE THINGS FIRST.
Regards
Roxy