S4 headlamps vacuum

[nickspeed]

Hello. Headlamps on my S4 take a while to pop up, which I guess means insufficient vacuum. The existing arrangement, which I inherited with the car, is as per the arrowed photo. Have not taken it off yet, but don't think the current arrangement includes a non return valve?? I have bought an NRV and union as per the other photo. I guess the union screws in to the manifold, and I then need some nylon pipe to join the union to the NRV, and then some more pipe to run from the NRV down to the front crossmember reservoir? The existing rubber pipe in fact connects to a nylon pipe (coming from the reservoir) near the radiator, and if I know what fitting to get I could join the to-be-installed nylon pipe from the NRV to the existing pipe near the radiator? All thoughts appreciated. Thanks in advance. Nick

[oldelanman]

Slow operation may not be a vacuum issue but could just be the pods binding on their pivot bolts .. have you checked that the pods move freely by hand ?
Can you raise your headlamps with the engine off after having been running for a while ? If so you definitely have a non-return valve fitted somewhere. If not then you either have no NRV or you have a large leak in the system. First place to check for a leak is the plastic T piece connection on the front crossmember., they are prone to failure. Also with no NRV your headlight pods would probably drop when going uphill and rise when going down on overrun with the throttle closed .. does that happen?
Looking at your photo there appears to be a fitting of some sort just after the short length of rubber hose from the manifold connection, that is the usual location for an NRV so worth checking that out. The original NRV on my car was fitted in that location, totally inside the rubber hose and completely obscured.

IMG_1745.jpeg (105.38 KiB) Viewed 941 times

Vacuum non-return valve

[nickspeed]

Thanks Roger. As you suggested, found the NRV downstream inside the rubber hose just before it changes to the nylon tube that runs down to the crossmember. Put a tester on it and indeed it had failed. Adapted a new NRV supplied by Kelvedon, and hey presto the headlamp pods flip up very positivley as soon as the engine is started. The installation also looks a whole lot neater. Thanks for your help !