Need some group theraphy

[Paco Anton]

Hi everybody,

I consider this board to be something like Porschephiles Anonymous and need some reassurance from the group.

6 months ago I had zero mechanical expertise. Since I bought my SC in May I have installed the short shift kit, checked and refilled the oil (dropping the dipstick in the process), adjusted the driver seat, adjusted the glovebox light and injured my finger folding the targa top.

Now my brake lights do not work. After reviewing the board I have diagnosed that my pressure sensors in the master cylinder are faulty (wow, 6 months ago I didn't know what a master cylinder was). So I have bought 2 new sensors (locally, sorry Wayne) and am ready to install them.

I would like to check with the board that the procedure is as simple as it looks: Remove front plastic cover, remove electrical connexions, unscrew old sensors, have some rags ready to clean brake fluid spillage, screw new sensors (no special torque requirements), reinstall electrical connexions, drive happily with brake lights.

Am I missing something?

Thanks for your help.

[Ted Stringer]

Yeah, you missed bleeding the brakes. After the system is opened you need to remove the air that was introduced to the system.

Get yourself some of the ATE super blue and the motive pressure bleeder and flush the entire system.

[Jdub]

Be sure to have someone in the car who can apply positive pressure to the brake pedal JUST as you are removing the sensor. This pushes out the crap that has fallen to the bottom of the MC, purging the area of gunk.

Then a brake bleed. Get a Power bleeder to make this easy.

John

[Superman]

I wonder if there is a method that can ensure that air does not get into the master cylinder. Air in a master cylinder sometimes cannot easily be bled out. If air gets in there, and you don't want to remove the MC to 'bench bleed' it, you can sometimes raise the front of the car, bleed, raise the rear, bleed, and get the bubbles out without removing the MC.

Or perhaps changing switches does not present this danger (air in the MC). I just don't know. All I know is that air in a MC can be difficult to bleed with the MC in the car.

[Paco Anton]

Ted, John and Super,

Thanks for the help. I had not realized the need to bleed the brakes. Following your suggestions I managed to replace the switches AND then bleed the brakes.

When I replaced the switches, brake pressure at the pedal was zero. I bled the brakes and brake pressure was back to normal.

I used a friend's garage about 50 miles from any major city. If I had not known about the need to bleed the brakes I would not have had the required parts handy (101 projects, Wayne's tech article, brake fluid, jack stands) and would have been stuck with a non driveable car.

Thanks again, if you ever come to Spain remind me to buy you a couple of beers.

[john walker's workshop]

if you do one switch at a time, and have a helper, leave the switch somewhat loose and have the helper slowly push down on the pedal while you watch for air bubbles at the threads. stuff a rag under there to save the mess. when the bubbles are gone and just fluid comes out, tell the helper to stop and keep the pedal where it's at, as you finish snugging up the switch. then do the next one. to keep any more fluid than necessary from leaking out, have the new switch in your other hand, and as soon as the old one is out, start screwing in the new one. sometimes you don't even have to bleed, as the minor air bubble, if any, just goes upward into the reservoir.

[john walker's workshop]

double post.

[Paco Anton]

Thanks John,

I tried to do it that way but did not suceed (novice mechanic but definitely improving ).

Now the brake light indicator stays on. I will try later the battery reset trick you indicated in some other post.