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Thanks for you input . I'll take it with the dealer next time I'm going there.
Originally Posted by silverd2
INCORRECT!
When the ignition is turned off, the vacuum is electrically released instantaneously. Then the HEAVY spring tension of the changeover pivots (unless they are seized) pulls the pods open.
If this doesn't happen INSTANTLY, the pivots are NOT moving freely and need servicing (cleaned and lubed)...OR the electric solenoid valve(s) is malfunctioning.
Any dealer or mechanic that tells you differently is incompetent and/or full of crap...to put it politely
Any chance you have that same diagram for an s8? Can you confirm that the s8 has two actuators for the vacuum pods (like the a8)? It's my understanding that they operate independently on the a8, but as the s8 only has 2 stages as opposed to 3 for the variable intake runners they operate simultaneously. Any thoughts?
Hey there. Thank you for this super informative and detailed DIY. I did the upper pivot this morning as a proof of concept and will do the other later. I found that it is not necessary to remove all the hoses though which is a bonus.
After re-installing everything (except the spring) the arm did not fall down all on its own. I had to give it a little nudge. Afterwards, I installed and tightened everything, but upon starting the engine the pods did not move inward. There was a slight improvement, but nothing like it should be.
I traced the air lines, and found that one of the nipples on the solenoid valve towards the rear of the engine (part # 077906283c) had broken off. I have ordered a new one which should arrive tomorrow.
If this does not solve the problem of the pivot arms moving, what would be my next course of action?
(btw, I have a Touareg V8 with the 4.2l AXQ engine)
Well I replaced the solenoid but still no change. When I start the car I can see the vacuum pods deflating somewhat, but they do not retract inward. I check all the surrounding hoses, none of which seem to be leaking.
If both pivots can be hand-turned to stop and will return to stops under spring pressure, all is well mechanically.
If pods will not fully evacuate (pulling both pivots to idling stop) seconds after starting the engine, you still have a vacuum (or changeover solenoid) problem. If you are SURE all vacuum lines are perfect (INCLUDING line(s) to the" hidden "vacuum reservoirs), then check the actual vacuum pods for holes/rips in rubber or a crack in the plastic body. I had trouble finding a small leak once (same symptoms as your) and found a crack in the plastic pod body itself.
Keep lookin............
This might be a stupid question but could it be the springs? after dremmeling out the inside of the casing the rod fit perfectly and could be turned by hand. The bottom one fell into place under gravity. When the springs are fitted the are still very hard to press to the stopping point.
On the flip side, it might be my imagination but with the engine running there is a noise like rushing air coming from the left side. The two vacuum reservoirs are on the left side under the bumper, so that will be the next things I check.
I found the culprit! The vacuum hose that runs from the top of the engine down to the vacuum reservoirs was melted clear through. Mended it and the pods evacuated when the engine started. Good, clean, solid vacuum. I have ordered a new one :-)
12-24-2012, 12:52 AM
