2004 CTT - Brake Booster Faulty P1431 - replacing vacuum lines

iamtheari · 07-29-2014, 06:39 AM

I've had this warning for a while. The brakes work fine so the booster itself is not actually faulty. Research online tells me that the most likely cause is a leak in the vacuum lines from the brake booster vacuum pump to the brake booster. I took the time to trace these lines last night, the best I could in a fly-infested garage, and found one cracked plastic pipe. I sealed it up with electrical tape and zip-ties but the warning came back on this morning after about 1 mile of driving. I don't know if it's the same spot or not.

What I want to do is replace the entire set of vacuum lines relating to the brake booster. But there are two problems with this plan:

1. I do not know quite what is required. The PET is not clear and does not seem to quite exactly match my car. Illustration 604-00 is the only one that seems to relate to the brake booster system and it includes the pump, the booster, and two vacuum lines. But when I inspected mine there was first a vacuum line from the pump toward the front of the car, down to the floor, then out toward the quarter panel, then back around toward the engine, then back up toward the hood, then back toward the firewall where it connected to another line. This appears to be #14 in the illustration (part 955.355.579.01 or its ilk). But mine has some kind of a T fitting with another line attached to it underneath where it loops around for no apparent reason. Does anyone know what I'm missing here?

2. I have no idea how to replace item #13 from the illustration (part 955.355.577.01 or its ilk). This appears to go back into the bowels of the car where everything is impossible to reach. It appears that you need to remove at least one of the windshield wiper assemblies to remove the lid to this compartment and even then I have no idea how much of a rat's nest I would be looking at. This is the part that included the crack that I found so it definitely needs replacement. Has anyone dealt with this area or maybe even this specific part before? I don't want to dive in unless I know where I'm going.

The alternative is to have a dealership do this for me, but the nearest one is 400 miles away so that is not ideal. Thanks in advance.

iamtheari · 07-29-2014, 08:53 AM

Looking around, I found that ECS Tuning has replacements for these parts with color photos so I know that the part numbers are correct despite the PET drawing not showing the exact arrangement for my car.

That leaves the installation of item #13 (part 955.355.577.52 for my VIN). It really looks difficult to do so I am hopeful someone can chime in with hints about the process before I spend money on parts that I can't install. Thanks.

iamtheari · 08-09-2014, 09:28 AM

So the parts are here other than new wiper arms, due Tuesday. I am installing the updated wiper arms to fix bad performance in passenger side and noise on driver side. Common issue, it seems, and now is the time since the wiper arms have to come off to get to the long vacuum line.

For now I'm taking a break to let penetrating oil soak into the passenger-side nut on the passenger-side wiper arm. It appears that the only thing that would keep the bolt from spinning is a notch in the bolt that must match with a notch in the wiper arm, and my wiper arm must be damaged as the bolt just spins. I used a Drexel to out a notch in the bolt to get a screwdriver into, but it is still too stubborn. Torching is a last resort because of the sensitive location surrounded by rubber, plastic, and of course the hood. I don't have a small precision torch.

The three-headed snake vacuum line went in okay, although the heat shield tore a bit pushing it under the engine torque mount. In hindsight, I would wrap that with tape to protect it if I did this again. I hope I don't have to, of course.

914-6Porsche · 914-6Porsche's Garage

I had the vacuum line to the vacuum assist pump fail a long time ago and the dealer charged about $500 to replace it. I just had the starter replaced because the starter bendix had been washed down with leaking coolant from the coolant pipes that had been replaced about 30K miles back. While they were in there they found some other vacuum lines that were cracked, it hadn't given me any warnings, so those were replaced. I hope you never have those problems.

iamtheari · 08-10-2014, 10:58 AM

I hope I don't have other vacuum line issues in that area because it looks crowded, but I guess I'll try to see what I can see while I'm in there. Thanks for the tip. I need to find a wiper arm puller to get the passenger wiper arm off before I can get the cowl open. My steering joint puller worked for the driver side but you can't slip it over the passenger side arm.

iamtheari · 08-13-2014, 04:47 AM

Well, as usual, Porsche placed a connection in a place you can neither see nor reach. Does anyone have tips for getting the vacuum fitting stuck back into the brake booster? I am tempted to turn on the car and get some help from the vacuum pump itself but I really don't believe it should be this difficult.

iamtheari · 08-13-2014, 12:49 PM

I managed to get an 11/16" wrench over the wider piece of solid plastic at the end of the vacuum line, a 1-1/4" wrench head between the other wrench and the firewall to act as a fulcrum, and enough of the pipe shoved into the booster to feel comfortable (tiniest gap remains). The grommet on the other end of the line, where it comes back in front of the firewall, is a major chore due to the location. And getting the other end connected to the three-headed-hydra vacuum line was also a chore. But I just drove 20 miles without a warning light for the first time in months.

If I tackle the parking sensors and get to my friend's house to reset the Service Now reminder with his Durametric, the car will have absolutely no warning lights or unusual beeps when you start driving at all. That will be really nice. But for now I'm just glad that the only "this thing has failed and could directly reduce controllability of the car" issue appears fully resolved.

Tip on this project: Replace the wiper arms while you're at it, but don't try to rush those. My passenger blade ended up an inch high at rest so I'll have to pull it back off, push out the bushing, and hammer it back into place when time allows. But that's cosmetic.