Separate each connection from the check valve forward, one at a time, and plug the engine side. When you reach the spot that makes the engine run poorly, that last run is your culprit. I seriously doubt that the metal tube has holes. The hose from the metal tube to the booster itself is a possibility. IF you plug that hose right where it joins the booster, and the engine still runs well at idle, then the booster itself is leaking OR the rubber o-ring between the master cylinder and the booster may be leaking. Do not just tighten the master cylinder-to-booster nuts in the hope of fixing it. It would require removing the master cylinder from the booster and cleaning up the connection and installing a new o-ring.pdlrofdrms wrote:Okay so there is a vacuum leak in the brake system.
I found this out by removing the check valve plugging the line to the engine with bolt and clamping it down.
Engine ran great.
All cylinders firing even and participating. No more lumpy idle.
So now I have crawled under the car with a big ol flash light. I checked the connections and looked for tears, holes, etc.. none that I can see.
I called my VW friend in SD. He said its not super common but sometimes the metal tubes can get holes in them and to run my hands along all the metal tubes and check for any rust and holes.
Sigh...
I did get a new brake booster and Master cylinder I was hoping to store it away until I actually needed it.
Maybe I actually need them.
I do not see any oil leaks at all around the seals and or connections.
So I feel a little stuck.
Back out to re examine the hoses.
Colin