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?

[zaq123]

Just to follow this up. It was a freak incident where brand new $40 ATE check valve failed/felt apart internally and was rattling inside randomly opening/closing with vacuum pulses. And the noise was transmitting to the booster itself.
Here it the one I used.. I mean for that price I expect it to last https://www.ecstuning.com/b-ate-part...004313507~ate/

Well since I was on the booster fix, I decided to make a little more room for my ITB box and went with 944 booster. I just wanted to drop RHD ITB air box enough to get good hood spacing. With hood sitting adjusted to fender line, airbox was hitting the hood ever so slightly. I enlarged trumpet to airbox back plate mounting holes slightly to have a little more adjustment room but stock booster prevents it from dropping the airbag to really give it good clearance.


I was able to find new one for $200 shipped. I made an aluminum spacer out of 3/4" plate as I wanted all brake lines to line up as with OEM booster. I didn't; want to start replacing lines etc. For this thick spacer, booster studs are not long enough. I had to cut them short and extend them with M8 coupling/stud/red loctite. M8 round couplings also hold that spacer tight agains the booster with some RTV in-between so no moisture gets into the cabin. OEM gasket to the firewall.
I've seen someone makes shorter spacer ....appears to be 3d printed. I didn't want to go that route as I wanted little to no flex when the pedal is pressed. Also their spacer is 1/2" as they say but I don't see how locking nuts can be fully seated with 1/2" spacer. There is a maximum 1/4" of extra thread. But 1/2 is too short anyway to make stock lines work unless they are reshaped. Even 3/4" (19mm) spacer I made is still a little short but only by 3-4mm which stock brake lines can easily make/flex to. I just could not find 23mm block of aluminum and this 4"x4"x3/4" block was $20 shipped on Amazon.

Just an idea if someone needs a booster and can't find stock one since they are NLA. Booster clevis rod still needs to be shortened/ threaded. A section of the thread will fall on rods dimpled section where 8mm wrench can hold the rod. However once that dimpled section is threaded, there is still enough thread to keep the clevis/jam nut tight.
As a tip, don't use wise grips as many do to hold the rod while threading, you will booger it with wise grips. Just run the tap down on existing threads, put double nut (m10) on the top to keep the rod with the wrench from spinning and continue down the rod with the tap to make new threads.