It was brought to my attention that one of the actuators for my variable manifold was broken, the vac nipple is just snapped off. While i was taking a look at this i realized that the second actuator is locked in the actuated "under vacuum" position even when the car is off. I gently tried to move it back to the correct position and it seems to be stuck.

I am going to replace both actuators as soon as the parts arrive, but is there any chance that the manifold flapper itself is stuck? If so what could cause this?

Thanks in advance for your help.

 

The only difference reported - you'll notice after the replacement - is the reduced weight of your wallet.

 

ouch... you can fix that nipple by drilling and tapping it out then inserting a new nipple.

 

Just remove the vacuum actuators and rotate the change over shaft, it should move easily. Check the seals before closing things up, watch out fro the spring under the actuator unit. Actually, the whole mechanism should move under hand pressure if all is well. Since you are replacing the actuators, you don't need to worry about them, just be sure the shaft is free in the manifold. Test the mechanism by observing the actuator unit as the engine gets to 4200 rpm, the actuator should function at that time and rotate over to the short intake tract.

 

Ok so I took another look at them today, the "arm" attached to the broken actuator does not seem to want to move at all. Ive tried to move it with a decent amount of pressure and it wont budge. The actuaor that is not broken also seems to remain engaged well after the car has been off (like the next day) but sometimes appears to diengage. I have absolutely no idea what could cause that besides the flaps themselves possibly being stuck inside the manifold.

 

So Ive messed with this alittle bit and it seems that the assembly in the front of the manifold (the spring) is most likely whats gummed up. I can move it back and forth by prying it gently but it will not move under its own power. I have tried freeing it with, penetration oil, wd40, carb cleaner and graphite lube. Its not getting any looser. Does anyone have any idea how to fix this without disassembling it?

 

if carb cleaner didn't get in there, you might have to take it out and let it soak in gas (assuming it doesn't have any rubber seals, I don't know what the thing actually looks like).

 

Exactly which parts did you order and replace here? One of my plastic arms broke and after a few attempts using JB I found success with simply using safety wire to bridge where the arm should be. I've done about 6k miles since the fix without any problems. If the actuators are supposed to move easily then I may need to replace some actual parts because it is difficult to move by hand/finger.

 

Go to www.gruvenparts.com and order the intake manifold links measuring your old ones to make sure of the correct size. These are bulletproof and made from billet aluminum and unlike the crappy plastic ones on the 4.2's, will never break. The plastic nippled actuators that control the variable intake runners will seize up because once the link rods break they no longer move and carbon deposits build up along the shafts that move them. The shafts run from the front to the rear of the engine so you must lube both ends. The rear portion of the shaft is designed to accomodate a torx bit and can easily be manipulated using a suitable tool as you risk breaking it from the front by exerting too much pressure loosening the actuator. Also note that the front actuator can also be loosened using a smaller bit and I recommend loosening that one too. I removed my intake manifold to accomplish this more thoroughly but it is not necessary unless you wish to replace the intake manifold gasket. The rubber bellows (diaphragms) cannot be purchased individually and only come as an $800 kit (two bellows and two link rods) from the Stealership. Fortunately, the exact same bellows (diaphragms) were used on mid to late 90's Land Rover Discovery models to actuate the cruise control units and are available from that dealer for $100 each. I purchased two perfect used ones for $40 at a local Land Rover salvage yard. This is the easiest most cost effective solution to this problem and solves it permanently. Lastly, use Seafoam or warm water to decarbonize the manifold but you have to be extremely careful when introducing it through the vacuum inlet port. Then crack open a cold one and light one up...you're done.

 

I came across this writeup on freeing the assembly. Im going to tackle it as soon as I get a rain-free sunday. Just incase someone else finds it useful:

http://forums.quattroworld.com/a8/msgs/44689.phtml