77 Westy Brake and Vacuum and Booster questions

[JereandJess]

77 Westfalia 2.0 FI

I will ask my questions first then go into the descriptions of the problems. Sound good?

How can you tell your brake booster is bad vs. having a vacuum leak in the vacuum line to the brake booster, aside from putting a known good one in there?

Will a bad booster give you symptoms of having a vacuum leak?



Here's the situation....Our green bus has started having a very poor idle, coinciding with the brakes doing something weird. When I step on the brake pedal coming to a stop, the brakes catch and start working, then the pedal releases a little bit, and the pedal goes down at the most another inch without resistance, then it catches again and allows me to come to the complete stop. If I pump the brakes quickly, there's no problem again for a little bit, but it comes back.

I suspected the master cylinder, not taking the idle into consideration.

Now I am thinking that the brake booster could be bad. I know they go bad, and I know there's a guy in Texas that will rebuild them quickly, but how do I know this is the problem?

I did remove the hose going to the booster, and plugged it up, along with the nipple on the plenum and the hose going to the decel valve. Guess what? Idle returned to it's regular perfect state and the brakes were hard as ever to make work, because they were not getting the benefit of the vacuum assist through the booster, right?

So now that I rambled along, what do you guys think? What course of action would you take?

[vwlover77]

As a next step, I would reconnect the hoses in the engine compartment, but leave the hose at the booster end disconnected and plugged.

If your idle is then good, the hose to the booster is NOT the problem. Maybe the booster is bad, if that's the case.

If the idle gets bad again, something is amiss with the hose to the booster.

[JereandJess]

I pulled the booster off of a 72 bus that is a mess, but I am not ready to totally give up on. I just keep waiting for the stars to line up financially and learn how to weld on that bus then bring all the rest of it back up to speed. So it just sits until then.

Anyway....

The booster on that bus I sent off to H&R Automotive in Texas. Sent it on Friday via Post Office, he got it on Tuesday, back to me via UPS on Wed and I received it on Friday. He cleaned it all up and it looks great.

Here's the thing, I really thought that 72-79 boosters were the same.

Guess what? They are not. The one on this 72 is smaller. I couldn't get it to hook up.

I never crawled under the 77 to check it out to compare it first.

I had planned to get it back, all rebuilt and ready to go and then swap them out. Then one day when I start work on the 72 I would get the 77 booster rebuilt for it.

I guess now I have to send the 77 booster off to H&R.

It's just tough to throw down the $$ for that again so soon.

Can anyone tell me what years are compatible for the late bay? Is it 74-79? 73-79?

Just curious.

Anyway, I put the new German ATE master cylinder on the 77 and once I figured out that the rebuilt booster didn't fit, I hooked it up to the 77 booster anyway and the symptoms are better, but similar.

Guess I need to bite the bullet and send the 77 booster off to them.

Anyway, that's where we stand with this.