Vacuum Hose / Sliding Venturi Question

Talk and Tech about turbocharged 924/944/968 cars
User avatar
whalenlg
Posts: 403
Joined: Mon Jul 05, 2021 8:58 am
Has thanked: 8 times
Been thanked: 109 times
Trying to rework my vacuum hoses to pass the CA smog visual inspection (tail pipe was fine, but previous owner left very visible vacuum line stubs when removing the cycling valve and adding a manual boost controller + Lindsey DP wastegate).

After I got the intake manifold off, I noticed that the Venturi connection that loops back to the brake booster slides back and forth. That really didn't seem right and my google searches didn't clarify whether that's normal or not. See pics that show in and out positions (finger pointing to the area of interest).

So - is it normal?

If not, what's the best way to resolve it?

(Since I am trying to NOT fail another inspection, removing the Venturi's is not a short term goal).

Thanks!
Add Pictures/Files
IMG_9568.jpeg
IMG_9568.jpeg (1.87 MiB) Viewed 817 times
IMG_9569.jpeg
IMG_9569.jpeg (1.99 MiB) Viewed 817 times
1986 951 - Silicon Valley

#1

Zirconocene
Posts: 191
Joined: Mon Apr 04, 2022 4:59 pm
Location: PDX Adjacent
Has thanked: 78 times
Been thanked: 48 times
I don't think that's normal but I also don't have a clear memory of that on my car.

What about just putting a jubilee clamp on the other side?

Cheers
Cheers

1990 928 GT
1990 928 S4
1991 944 S2
1993 968
2002 911 C2

#2

User avatar
Tom
Site Admin
Posts: 8933
Joined: Fri Jun 25, 2021 2:04 pm
Location: Silicon Valley, CA
Has thanked: 932 times
Been thanked: 3994 times
Contact:
I don't think it should be loose either, but from memory they are both plastic so you might need rtv or something to seal it? That said, I deleted the venturi on my car over 20 years ago and have never had a smog tech say anything. I used all factory parts made for the '88+ 951, so basically superseded factory parts.

#3

User avatar
whalenlg
Posts: 403
Joined: Mon Jul 05, 2021 8:58 am
Has thanked: 8 times
Been thanked: 109 times
I pulled it out and it just slid out completely. I saw some variations online that have an o-ring, but there's not really a groove on this one for that.

I think I'll just RTV it in place as suggested and go from there.

I will definitely delete it at some point, I just can't take the risk that the next smog visual will look at the vacuum diagram and ask where the venturi is.
Add Pictures/Files
IMG_9571.jpeg
IMG_9571.jpeg (2.33 MiB) Viewed 796 times
1986 951 - Silicon Valley

#4

User avatar
whalenlg
Posts: 403
Joined: Mon Jul 05, 2021 8:58 am
Has thanked: 8 times
Been thanked: 109 times
No issues since - RTV sealed it. My boost gauge shows better, more consistent vacuum at idle (there were a lot of other vacuum hose cleanups besides the venturi).
1986 951 - Silicon Valley

#5

Post Reply