Vacuum noise from a '71 NSS

[The Tassie Devil(le)]

G'day all,

I have been presented with a 1971 Eldorado that has a vacuum leak (noise) coming from the Neutral Start Switch (NSS) when the gear selector is in Reverse and Drive positions.

I went to compare the hosing with my '72, and the switches, and hose orientation is different.   The '71 has 4 hoses connected to it, via 2 plugs, whereas the '72 has 2 hoses via one plug.

Any ideas as to what the problem could be?

Thanks,

Bruce.

[TJ Hopland]

Its the plastic section still firmly attached to the metal section?

[cadillactim]

The four port vacuum connections on the NSS started in 67. All four ports were on the NSS through 73, however the later ones only used two of the ports (on one side). Two of the ports are for the brake release and the other two are for the idle speed up. The idle speed up was changed to electric, and thus two of the ports were no longer used. This is apparently why the 72 only has two vacuum lines and the 71 has four.

Concerning the leak, the vacuum hoses could be connected to the wrong side or connected upside down. Another possibility is the valve inside the NSS is cracked or broken and thus leaking vacuum. If memory serves me correct the bottom port is the vacuum feed, and the top port goes to the parking brake actuator.

Tim

[Julien Abrahams]

Could also be that the switch just needs adjustment. It is quite simple. Put the gear selector in Neutral, then loosen the two screws that hold the switch to the column. Move the switch somewhat (left or right). The starter should work when the lever is in Neutral. Also make sure the back up lights come on when you put it in reverse. Start the car, and move the gear selector to see if the noise is eliminated.

["Cadillac Kid" Greg Surfas 15364]

Not that this helps, but my 72 Eldo had a 4 port switch, and I know that was original because I bought it new.
That doesn't justify the leak, but as Tim says, I would check to be sure the two connections are FULLY installed on the correct nipples of the switch.
Greg Surfas

[The Tassie Devil(le)]

G'day Tim,

Ah ha!!!   I see it now, and it all makes sense.

The original switch on the car had been pulled to pieces and put back together with wire as they broke a couple of lugs when opening it.   I thought there was something missing, but found it totally saturated with grease.

I have a spare switch, and carefully dismantled it, and will post pictures of what I found.   There are two small holes in the plate that vent to the outside of the switch, and as this car has no Idle Speed-up operation attached, the hoses that go through the firewall will have to be traced.   They disappear behind the Brake Booster.

When I started working on this car, it was missing lots of stuff, in the engine bay, and the engine actually had a 120cc head on the left side, and a 76cc head on the right.   Someone had definitely been doing something wrong.

Will get the car back soon, and delve deeper into contorted positions as I slowly search.

Bruce.

[The Tassie Devil(le)]

Can anyone assist me with a vacuum routing diagram for the NSS/Park Brake release switch for the '71 Eldorado?

I have scoured the Shop Manual, and cannot locate anything that shows the routing of the 4 lines.   I know that one goes to the Park Brake release "motor" and one to the one-way valve, which are on the inboard side of the switch, but nothing on the other two lines that go forward through the firewall.

Thanks,

Bruce.

["Cadillac Kid" Greg Surfas 15364]

G'day Bruce,
Unless someone has done some "modifications to the hoses, there should be two pairs of hoses, each with a mounting "base" that goes on the switch.  If the switch is working and you have it adjusted correctly (by "timing" the back up lights in Reverse) you should only be able to install the hoses in one way.  Installing (or trying to ) them backwards will not fit correctly.
Gre3g Surfas

[The Tassie Devil(le)]

The switch is correctly installed, and there is no vacuum leak when in park or neutral, but leaking in drive gears.   Plus the park brake will not automatically release, even though I have a vacuum source coming from one of the hoses that come from the firewall to the left side of the switch.

What I would like is a photo of the area of the firewall, on the engine side, next to the brake booster, between that and the fender to show where the two hoses go to get their vacuum from.

Bruce.