HELP - 69/70 Vacuum leak. What is this hose?

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bsbeck
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HELP - 69/70 Vacuum leak. What is this hose?

#1

Post by bsbeck » 10 Oct 2018, 20:07

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Top picture, what are those 2 hoses (one big and one little) right above where those electrical wires go through the firewall? Big one goes to top of vacuum tree. Small one goes to intake manifold. They come in about center under the dash and then run down on the far driver's side under the dash to above a green electrical box and I can't tell where they go from there. The issue is the big one is a vacuum leak and makes a sucking noise under the dash. If I pinch it shut, the sucking noise stops. I have no clue what those 2 go to. Can someone help me out???
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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bsbeck
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Re: HELP - 69/70 Vacuum leak. What is this hose?

#2

Post by bsbeck » 10 Oct 2018, 20:21

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I think it's what I've got circled in red on this diagram. Except my big hose goes to the vacuum tree and the small straight to the intake manifold.
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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bsbeck
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Re: HELP - 69/70 Vacuum leak. What is this hose?

#3

Post by bsbeck » 10 Oct 2018, 20:21

Mine is a non-A/C car.
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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canted 393
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Re: HELP - 69/70 Vacuum leak. What is this hose?

#4

Post by canted 393 » 10 Oct 2018, 21:02

My best guess is vent door / heater control a lot of things like headlight switch are all vacuum operated on a cougar compared to a mustang. Just unhook it and plug the port and see if anything changes. I have to replace my heater core this winter so I am in for some fun.

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Mike_B_SVT
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Re: HELP - 69/70 Vacuum leak. What is this hose?

#5

Post by Mike_B_SVT » 10 Oct 2018, 21:36

I believe that is for the Dist-O-Vac, which is the vacuum operated distributor control doo-dad thingamabob (can you tell I have no idea what it actually does?). It showed up on the '70's, and I believe it has something to do with emissions. There should be a gadget that hooks into your speedometer / part of the speedo cable that goes along with it.

That's all I got :-(

*I wonder if that might be part of your throttle response problems.
Mike B.
CCOA # 9553

1970 Cougar Eliminator (Competition Gold / Black Decor Interior)
1 of 70 with 428SCJ, Ram Air, 4-speed.
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canted 393
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Re: HELP - 69/70 Vacuum leak. What is this hose?

#6

Post by canted 393 » 11 Oct 2018, 05:10

I missed the electrical box part, unhook it and see if your motor runs better then is it the hose leaking or is something still unhooked. My headlight switch did that if the hoses get hooked up wrong.

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bsbeck
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Re: HELP - 69/70 Vacuum leak. What is this hose?

#7

Post by bsbeck » 11 Oct 2018, 08:02

WOW, apparently it's mystery hoses and the mystery Green box. I have no clue what any of it is but I'm capping those suckers off and getting back to tuning it.

Does everyone else have that little green box???????????? Those hoses disappear right above that box. Maybe they go into it? I'll take the cover off that box tonight.
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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Don Rush
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Re: HELP - 69/70 Vacuum leak. What is this hose?

#8

Post by Don Rush » 11 Oct 2018, 09:37


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bsbeck
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Re: HELP - 69/70 Vacuum leak. What is this hose?

#9

Post by bsbeck » 11 Oct 2018, 10:01

Ahhhhhhhhhhhhhhhh, thank you Don Rush. So obviously something is awry in my little bluish green box. I found more info on WCCC's site about this setup and I'll post it below for others to learn as I did.

The big question now is......... Can I just plug off the two vacuum lines and everything be ok? The car is still running a little sluggish and I'm sure the vacuum leak at that box is at least part of the problem.


******************************************************************************************************************************************************************************

The purpose of the distributor modulator system was to help reduce carbon monoxide and hydrocarbons.

Distributor modulator system was standard equipment on some 1970 Ford Mercury Lincoln vehicles. We see it only on the 1970 Mercury Cougar and Ford Mustangs with the M code 351-4V Cleveland engine and FMX automatic transmission.

The purpose of the distributor modulator system was to help reduce carbon monoxide and hydrocarbons. Sometimes it is referred to as the Dist-o-vac system. The basic premise of the system was to use carburetor venturi vacuum to reduce engine emissions. This was performed by controlling distributor spark advance. A retarded spark provides hotter combustion chamber and exhaust manifold temperatures that cause more complete burning of the fuel.

The three main components are the Electronic Control Module, Speed Sensor, and Thermal Switch.

•Electronic Control Module is the black box which houses the PC board and solenoid valve. Ford part D0AF-9E718-S, in the manual it is described as having a black box and a blue cover, we also see them with black covers on the black box.

*Side note – There is also a white colored box along with black, blue, and white covers. This combination of boxes and lids make for 6 differently identified units for a range of other applications.


•Speed Sensor this actually is often confused with a cruise control part. It mounts inline on a two piece speedometer cable, it also has a two wire plug coming out of it. Ford part number D0AF-9E731-A.


•Thermal Switch this measures temperatures and only engages the modulator system on, at temperatures above 58°F. Ford part number D0AF—12A164-B.




For a 1970 Mercury Cougar or Ford Mustang the black module box will 'cut in' at speeds of approximately 23 mph and 'cut out' when speeds fall below 18 mph, provided that ambient temperatures are about 58°F.
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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bsbeck
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Re: HELP - 69/70 Vacuum leak. What is this hose?

#10

Post by bsbeck » 11 Oct 2018, 10:06

Those 2 hoses I thought disappeared behind that little box actually go into the box...
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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