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?

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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)

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

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.

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

If you find the vacuum valve on the parking brake is leaking plug the hose going to it until you can repair it so that that is one less leak into your vacuum lines preventing that system  from working correctly 

The brake should instantly release with a thud when going into a gear when the vacuum valve and NSS is working and the entire vacuum system is air leak free 

Honestly I never use the brake myself as Park secures the car from  any movement 

There is an arm on the brake to release it manually if needed

The brake should engage in Park with the engine on or off and then release when engine running going into R or D 

Mostly you need a vacuum system —free of any air leaks —in the entire cabin for the system to be working as intended

Testing all vacuum valves  and Cutting a 1/4 inch off the hoses and reinstalling them ( or sealing an air leak at a vacuum valve ) is a good place to start with  the vacuum lines to get the system sealed of air leaks as is intended 


The source of all vacuum in the cabin comes from the smaller hose fittings just behind the carb on the intake manifold that go thru the firewall into the cabin 

For that reason any leaks in the cabin  vacuum system should be having a negative effect on the engines performance as  unwanted air is leaking into the intake manifold that should not be getting in there 

Air leaks into the intake manifold will cause the engine to run leaner producing heat and reducing power 

You can plug the fitting behind the carb going into the fire wall until you are sure the cabin vacuum system has been gone thru to be sure it is working as a sealed unit as intended 

Doing that and checking you have a good  distributor vacuum advance valve should prevent most  general engine vacuum intake issues 

Use clamps on all vacuum lines that go into the carb —except for the dist advance hose on both ends 

Vacuum lines need to be air tight and sealed closed to do there job as intended 




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