I have owned 2 of these Wiltec DVs and know of another 2 that just suddenly stopped dumping for no reason. Needless to say I took it straight apart and sorted it out.
While you have your DV apart you might as well give it a quick service.
Here it is, the sequential DV unbolted from the pipe. If it suddenly stopped dumping
there is a good chance it will rattle when shaken at this point.
Using a 2.5mm allen key and a pair of pliers, remove all 6 nuts and bolts.
Here are the component parts layed out, wipe everything clean with a cloth.
Replace the plain washer, the rubber seal (so it bowls inwards) and the grooved washer.
Screw on the nut, this is what usually comes off and stops the DV working.
Consider setting it in place with some Loctite thread lock liquid to stop it coming off again.
Place the spring on the other groved washer and place washer first into the cap.
Screw the pressure adjuster in so it just touches the internal washer.
Push the 2 parts back together and replace the bolts and the nuts.
Remove the 6 bolts from the front of the unit.
Give both surfaces a good wipe clean and then replace it and bolt it back down.
The rear pressure adjuster increases the pressure at which the DV opens the more the red bolt is wound in. If you don't tighten the silver locking nut down to the DV you will get air leaking from around the thread and over time the red bolt will fall out.
Again, once you have found a setting on this that is good for you, thread lock it in place.
With it all assembled again leave it for about 12 hours totally submerged in clean engine oil.
This lubricates deep into the DV, allowing it to move more freely.
Allow the excess oil to drain out of the DV before reinstalling it into the car.
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