Tracking Vacuum Problem -- Need Help

[Abner Mality]

I am still working on troubleshooting the vacuum system on my 1980 W116 300SD. I have learned, today, that there seems to be a problem at the white plastic TEE just above the vacuum pump check valve. To recap, I have 23hg at the VP check valve, 20hg at the brake booster and every other point I can check between those two points EXCEPT at that TEE joint.

At the TEE,I get a max of 17hg, and that is after about a 2-minute wait; the vacuum builds verrry slowly at that junction. Is there some type of vacuum regulation built inside the tee? Should I try to replace the tee? If so, where can I purchase said item, or should I get creative with a home-made solution?

I am having door lock and engine shutoff problems. Using hand vacuum pump, I can get engine shutoff at around 9hg, so I want to believe my shutoff valve is good. Driving the car or revving the engine does not help, either; engine still will not shut down with the key. I will post a pic of the offending joint if I can remember how, and thanks in advance for any suggestions.

[Aquaticedge]

you most likely have a leak in the shutoff line between the mechanism in the dash and the SOV on the IP. Trace the line carefully between the two. Any break or leak in there can cause a 'Key off engine run' situation

[Abner Mality]

Will be pulling the cluster tomorrow to check that very possibility. What I need to know is why such low and slow vac at the tee?