e30 M20 brake booster noise ???

[zaq123]

M20 with ITBs. Brake booster gets vacuum from the cylinder 2 intake runner through inline ATE check valve.
I have this weird ticking noise behind my dash, at idle only.. Seems to go away at about 1500 rpm. I put on a stethoscope and started listening: block, head, intake runners are all good, that ticking isn't there. But brake booster body and the check valve, I can hear the same noise. More so on the check valve. My MAP signal which is being taken from the vacuum manifold (all 6 cylinders ) is steady.
Could be that Schrick 288 cam with it's huge overlap is pulsating that check valve ball at idle speed?

[TobyB]

You've probably got a slightly leaking boost valve inside the booster itself, and you're hearing
it drawing air through the refill port in the cabin.

t

[zaq123]

You've probably got a slightly leaking boost valve inside the booster itself, and you're hearing
it drawing air through the refill port in the cabin.

t

Its a brand new ATE booster. The sound is more like a rod knock, freaked me out the first time I heard in on the first start of this new stroker. But it only can be heard inside the car or with a stethoscope on the booster body. Like metallic knocking sound that goes away past 2k rpm. .

[TobyB]

Whacko!

Maybe a valve that's not quite sealing is bouncing?
I'm totally making waffles up, here...

I had a Ford one that growled, once- it was so rusty inside that
the seal at the can around the outer edge of the diaphragm was leaking...

Can you find any air movement?

t

[zaq123]

all intake runners are silent.. for M20 that is.. All 6 of them. Than noise only can be heard on the booster body of the check valve..I thought ITB intake box was hitting it ar idle but I put some rubber mat in between them and the noise haven't changed. Maybe something inside that booster?