I have a 1982 240d and I'm wonder how much vacuum the reservoir in the trunk should hold and how long it takes to get to he proper reading.

I've had my car idling for about 15 minutes and my vacuum gauge slowly rose to about 16. I'm getting a 19 reading when hook the gauge up to the check valve that goes to the reservoir in the trunk.

Shouldn't the reservoir show 19?

I'm attempting to track down some door locking problems.

Thanks.

pete