Vacuum / Parking Brake / NSS Question

[Karl Schwarz]

I bought a 1963 Series 62 Convertible in July.

It makes a hissing sound when in neutral, and sometimes when in drive (when the shift is more to the left that the right. I assume this related to a NSS vacuum issue - does that seem correct?

In addition, the parking brake does not latch. From what I've read here, it seems the NSS issue causes the parking brake to fail to release, not fail to latch - do I have this right? The parking brake itself works as I have slowly driven the car and carefully pressed it down, and it does slow the car.

Any thoughts on first steps to troubleshoot? Any good sources for a NSS if that is what I need?

[Kurt]

The parking brake will not latch when the car is running and put into gear. It should latch in Park & Neutral or when the car is off in any gear. One of the functions of the NSS is sending vacuum to the parking brake release when the car is in gear. Check you vacuum lines going to the NSS & to the parking brake. If the hoses are good/attached, it could be vacuum leak elsewhere (NSS, parking brake diaphram, etc)

[Karl Schwarz]

Thanks! The brake won't latch when the car is in park - perhaps it just needs some lubrication on the catch

[3ft7bqmb7dryo]

There is a vacuum valve on the NSS, and that routes vacuum to a vacuum canister on the parking brake.  When in park, vacuum does not flow to the parking brake.  Once in Drive or Reverse, vacuum goes to the parking brake.   Check the lines and canister for a vacuum leak.  But it is common for the vacuum valve on the NSS to fail.

[Jason Edge]

If the vacuum valve on the NSS is leaking I have a good one that holds vacuum tight for $20 + s/h.