Hi Newold, thanks for replying.Newold1 wrote: ↑Sun Jan 28, 2018 4:34 pm Absolutely!
A manifold vacuum even in your vacuum chamber under the manifold if it is leaking under vacuum will pull oil up from the lifter valley area and send it through those individual ports into the ITB inlet runners and burn it. When you are decelerating you will have maximum vacuum and thats when it would happen the strongest.
Is there a way to plug temporarily 7 of the 8 holes and then put some slight air pressure into that chamber with a hose and just pressure when you blow on it to see if it holds any pressure. If it has a leak into the valley it should bleed of and you might even hear the leak if its quiet enough.
That is rather difficult as the hole is some distance down the intake tract and hard to reach. On top of that i need something that would stay in place against any air pressure.
As far as what has happened I'm still speculating. but the intake flange where it bolts to the heads and in the front and rear has a machined ridge where the plate is bolted on. It's not a thick plate, maybe 1-1.5mm thick. Thinking out loud here, but under vacuum the plate might try to bend inward (towards the runners, which would then stress the silicone seal and break it. This means it is probably leaking all around the edges.
It will have to come apart to fix. Not sure what I'm going to do against this bending. Maybe weld on some angular pieces or so.
On the other hand it might be better to completely delete the chamber and make a vacuum can of sorts with take off fittings in each runner.