Brake Booster Replacement Problem

[nicolas061291]

Hello dear Boxster lovers,

To start from the beginning:
I've bought my first Boxster about a month ago. It is a 1999 Model, 130k miles.
After driving some days, the break pedal felt somehow strange.
After another few days, the pedal wasn't coming up properly anymore, after releasing the break pedal.
I took it to the shop where they told me, that it is a problem with the break booster and that it has to be replaced. So far so good.
After taking the old one out they gave me a cool, that the break booster was filled with water. I've heard of that before, could be related to a clogged drain.
Good. They've replaced the break booster and cleaned the drain and told me I'd be good to go after they bled the system.
On my way home the breaks locked somehow (felt like the pads were pressed more and more on the rotors each time I pressed the pedal(maybe the break pressure didn't decrease after releasing the pedal)).
Now my car is sitting in the shop since Wednesday 05/11/2016 and the shop seems to have no idea how to solve the problem. They've bled the system several times now.
They've now called "experts" that should be able to tell them what's wrong (and are still waiting for their call back) and said that it could maybe be some "soft-/hardware problem in the control system".
I am in doubt that it is related to the control system. It seems like they've messed something up. What could that be?
Does anyone have any ideas? I don't want to buy a new control unit without any serious proof.

Thanks for reading my long question.
Thanks in advance to everyone.

Best regards,

Nicolas

P.S.: I apologize for any spelling mistakes, I'm not a native speaker. I've tried my best.

[Need_for_speed]

Nicolas, my understanding is that the design of the brake booster was changed in 2002 to incorporate a bellows on the booster to keep out water. Consequently, the old style booster was no longer available from that point on. In order for the new booster to work properly, there were other parts that need to be changed. Here's the link to the TSB: http://www.pelicanparts.com/techarticles/Boxster_Tech/57-BRAKES-Booster-ABS/TechBulletin.pdf

[nicolas061291]

Originally Posted by Need_for_speed

Nicolas, my understanding is that the design of the brake booster was changed in 2002 to incorporate a bellows on the booster to keep out water. Consequently, the old style booster was no longer available from that point on. In order for the new booster to work properly, there were other parts that need to be changed. Here's the link to the TSB: http://www.pelicanparts.com/techarticles/Boxster_Tech/57-BRAKES-Booster-ABS/TechBulletin.pdf

Thanks for the reply.
Where do I find the mentioned VIN? Is it the same as the one you use on Carfax or something else?
This could be a reason. Shouldn't the mechanic be aware of it?

Best,

Nicolas

[Deadeye]

The pedal has a return spring to bring it back to the rest position. It's a good idea to replace the master cylinder with the booster as they are both wear items. I don't think your abs has anything to do with the problem but you need a new technician that is familiar with this system.

There is a bellows (basically a ribbed rubber tube) between the booster and the firewall on the early 986 boxsters as well the later model years.

[Gilles]

Nicholas, several years ago i ran into something that may be related to your problem...

After replacing the master cylinder (on a X1/9) and bleeding the brakes everything was working properly, but after several miles the front brakes started to lock by themselves and when I inspected the front axle the rotors were way too hot (actually they where smoking)

However once the car cooled off, the rotors started to rotate again..., the problem was that I had adjusted the rod that connects the pedal to the master cylinder too much (it was too tight) and when the fluid got hot, it expanded and applied pressure to the pistons on the caliper, increasing the play of the pedal a bit allowed the master cylinder to operate properly when the fluid got hot.

Again, this may not be your case, but is simple to check and re-adjust.

Good luck!

[mikesz]

I have a 99 also. The early cars were prone to getting water in the brake booster due to the 2 piece rubber bellows and clogged drains. I did this fix myself when I did it I also replaced the master cylinder since I had the car apart anyway. If all they did was replace the booster you are subject to getting water in it again. there is a retro kit for the early Boxster. It is a hard rubber piece that pops into the firewall. it fits over the aluminum bar that connects to the brake pedal and goes into the booster. then there is a rubber hose similar to a radiator hose, its cerated or collapsible like an accordion that fits over the bar and over that hard rubber piece at one end and the booster at the other end. you then use hose clamps to clamp down both ends so no water can ever get in again. I did this and its difficult. I had the Porsche TSB and believe me you must follow it exactly. the original bellows is a 2 piece unit and allows water in. The fix is one piece and seals off the firewall to the booster. Pelican sells the parts to do this. There is also an adjustment process for the pedal also a TSB that must be adhered to. I think they changed the booster setup in 2000 not 2002 but not sure, I did this a couple of years ago.

Had an X 1/9 also fun car broke down a lot but easy to fix. Wish I had it today! Good luck! Contact me if I can be of any help. This is the reason why I work on my own car.

[nicolas061291]

Thank you all for your advise.
It was as Gilles said, the system was misadjusted and now seems to work properly again.
Obviously the mechanics had no idea what they were doing and I'll have to find a different shop for future work. (I should not have to tell the mechanic how his job's done!)
I'd love to do stuff on my own but it doesn't make sense for me to buy all that equipment due to the fact that I'm leaving the US in a few months. Good for me that the rainy period should be over at this time of the year so I hope there is no water coming in to the booster during my last months here.

Thanks again to everyone. You were of big help.

[Smallblock454]

Hello Nicholas.

good to hear the problem is solved.

Neil – who is also at this forum – did a video on how to exchange the brake booster. So you can see what has to be done if you're interested in.

https://youtu.be/LsVANgHiR84

Regards, Markus