No Power Brakes

[eb2143]

I parked the car at 11a after a normal drive with normal power assist to brakes and it shut down roughly, indicating vacuum leak/ASV issue. Went into work and 6 hours later no power assist whatsoever. Turbo seemed to be spooling up normally despite total lack of any power assist.

I know I have a vacuum leak. I'm looking for a little assistance troubleshooting as I'm not home and don't have any tools, like my Mityvac.

I have confirmed that the line from the vacuum pump to the booster is not the issue. This had been replaced a few years ago anyway. I have it off and I've gone over it very carefully. The check valve is working properly and there is no hairline crack.

I'm suspicious of the booster itself. Has anyone had the booster develop a vacuum leak internally or due to surface rust? The bottom of my booster is rusty and has been for years (yes I have a bottom plate in place).

Any advice how to proceed in troubleshooting with scarcity of tools? Any other "hot spots" for vacuum line damage/leak?

Can a small vacuum leak elsewhere in the system (I do think it would have to be small, as I can hear no air whoosh) really cause a total loss of power assist, or does this sound more booster-esque?

TIA.

 

[CotJocky]

Brake boosters do go bad. Can't say I've personally had one go bad on a wagen, but I have replaced them on several vehicles, including my dad's 97 GMC truck recently.

After the car has been sitting maybe 2-5 minutes, pull the vacuum line on the vacuum reservoir and see if you still have vacuum in it (hear a hiss/woosh when you pull the vacuum line). When done with that test, put the line back on the reservoir. If it wasn't holding vacuum, you know you have a leak. To test the brake booster, pull the vacuum line from the brake booster, crank the car and see if you have vacuum against your hand on the end of the line that goes into the brake booster. If you have what you feel is significant vacuum, that should leave the brake booster as the likely culprit.

 

[eb2143]

Brake boosters do go bad. Can't say I've personally had one go bad on a wagen, but I have replaced them on several vehicles, including my dad's 97 GMC truck recently.

After the car has been sitting maybe 2-5 minutes, pull the vacuum line on the vacuum reservoir and see if you still have vacuum in it (hear a hiss/woosh when you pull the vacuum line). When done with that test, put the line back on the reservoir. If it wasn't holding vacuum, you know you have a leak. To test the brake booster, pull the vacuum line from the brake booster, crank the car and see if you have vacuum against your hand on the end of the line that goes into the brake booster. If you have what you feel is significant vacuum, that should leave the brake booster as the likely culprit.

I did the vacuum reservoir test and confirmed that there is either no vac being produced or there is a large leak. I was too cold and lazy to test the vacuum pump, but since it is hard to imagine the vacuum pump suddenly producing no vacuum, I'm going with leak. The booster failed the booster test that is outlined in the Bentley manual. Car is going into a shop tomorrow and I will update thread with ultimate conclusion, but I suspect booster darn it

 

[eb2143]

It was the vacuum pump, stopped working out of the blue. $210 later, I'm back on the road. These DO fail. I have the old one and may try to find out how.