Air Cleaner Vacuum Motor Question

[Past Time 3]

Hello, first post here looking for some information that seems it should be obvious but.....

I recently picked up a 70 Mach1 that while in great condition had been sitting and has/had a bunch of minor issues (loose nuts, bolts, minor leaks, adjustments and such) that I've been picking off. The latest which I'm not sure is an issue is the vacuum motor on the air cleaner snorkel. I noticed that the door is always open and I'm unable to move it by hand, at least not with the amount of force I'm comfortable applying. I thought I would try test it's operation with a Mitty Vac  attached to the vacuum line going to the vacuum motor and noticed that I'm unable to draw a vacuum from the line. I've done this test with other vacuum motors and the diaphragm moves then holds the vacuum. This motor would appear to be completely open as I'm unable to build any vacuum. I tried blowing into the line and the air passes through it easily.

Not sure if this is normal but based on what I'm seeing I can't think it could be as this is basically a vacuum leak as it sits.

Can anyone confirm the correct operation and if indeed the motor is toast? If it were a $5 or $10 part I would replace it and call it a day either way but these things are going for $130 and I'd hate to get one only to find out this is somehow normal operation.

Thank you for any help..... Bill

[jmlay 71]

Should be open normally. Closes in order to draw warm air when cold. These may be rebuilt, however, not sure it is worth the cost or effort.

[Past Time 3]

Do you know if I should be able to pull a vacuum on the motor? If I put a line directly to the motor it is wide open, basically nothing happens when I apply vacuum. It's like it just going to a hoe on the other side.

[EastYorkStang 58]

Is the shroud below it rust free surrounding the exhaust manifold? The valve closes forcing warm air to the engine. Took mine off when the shroud rusted away.

[Past Time 3]

My manifold is in great shape, hot air tube is there. Do you still have yours? if so could you check to see if that vacuum motor actuates with you put vacuum on the motor?

[Past Time 3]

Talked to a guy at Ecklers today about this. His take was that if I was unable to pull a vacuum with a hose directly attached to the actuator then it was bad an basically acting like a vacuum leak. I ordered the part from them with assurance that if it operated the same I could return it. I'll update with my findings so if anyone else runs into this they'll have a definitive answer.

 

Thank you everyone for your responses.

[EastYorkStang 58]

Mine was ditched a few decades ago. Doubt the mechanism would work this time. 

[Mach1 Driver 502]

I'm just curious what triggers the vacuum motor for a 70. Is it some carb condition? I know there are different setups for different engines, and apparently its used as far back as 68.

On a 69 351W there isn't vacuum involved- its strictly controlled by the heat from the exhaust manifold. It is mechanical and there is a thermostat with wax as the internal working medium and a couple of external springs. When it gets hot enough it flips the heat door open for cold intake air. Mine still works after 52 years.

[jmlay 71]

If I recall correctly the vaccume line runs to a valve that closes when the engine warms up, cutting off vaccume to the motor. No or less vaccume allows the motor to open the door allowing ambiant air to enter the air cleaner. Door is normally open and closes with vaccume.

[Past Time 3]

This is how it was explain to me as well. The issue with mine is that there's no functioning diaphragm in the actuator now. It's basically an open vacuum circuit right now acting as if the line were disconnected. I have the new one ordered and will see what happens with it. Like all reproduction parts some are great and some well, don't work at all. It'll be a quick yea or neigh as to if this gets replaced. If the new motor actually works, wonderful. If not I'll do as York did and ditch the system. On mine I'll probably leave it in place to make it look stock but shunt the vacuum line going to it to eliminate the vacuum leak the open diaphragm is causing as it sits. I get the feeling this part hasn't worked since the car was restored and nobody noticed.

[Rich Ackermann 152]

5 hours ago, Past Time said:

This is how it was explain to me as well. The issue with mine is that there's no functioning diaphragm in the actuator now. It's basically an open vacuum circuit right now acting as if the line were disconnected. I have the new one ordered and will see what happens with it. Like all reproduction parts some are great and some well, don't work at all. It'll be a quick yea or neigh as to if this gets replaced. If the new motor actually works, wonderful. If not I'll do as York did and ditch the system. On mine I'll probably leave it in place to make it look stock but shunt the vacuum line going to it to eliminate the vacuum leak the open diaphragm is causing as it sits. I get the feeling this part hasn't worked since the car was restored and nobody noticed.

I am late replying to this topic, but just in case it is helpful in the future.  You can test the vacuum actuator using a brake bleeder pump. The vacuum actuator should hold at least 13lbs of vacuum without dropping (fast or slow). If it does not hold the vacuum then the rubber diaphragm inside is bad.  I have disassemble them in the past and repaired originals by sacrificing a cheaper plastic version. I take the diaphragm from the donor and replace the old one in the original. The hardest part is separating the actuator cap from the base. Make sure you have no leaks with the new diaphragm as it is sealed to the base.

Here are some brands of actuators that are very close to the originals in appearance and function that may still be available. Three things to look for when buy an aftermarket actuator the orientation of the tab with the mounting hole (should be at 11:00 with the vacuum hose port at 12:00) and the opposite tab (is at 5:00) to the vacuum hose port. The orientation and length of the hook that connects to the snorkel flapper. Finally the vacuum hose port size... some are larger in diameter.

Some of the all metal Ford Air Cleaner Vacuum Motor correct type actuators are:

Niehoff FE703 AC Vacuum Air Cleaner Motor Actuator

Avatar VM 263 Vacuum Air Cleaner Motor Actuator

Borg Warner EC518 D7TZ-9D612B Vacuum Air Cleaner Motor Actuator

Borg Warner EC517 BWD Air Cleaner Vacuum Actuator Motor VA13 ---is incorrect because the mount tab is at 1 o'clock instead of 11 o'clock

Some of the pictures are from when I restored a 1973 Mustang with Ram Air, but all actuators are basically all the same.

A factory original 1973 date coded (D73) Ford Snorkel Actuator I repaired as I described above.

1971 - 1973 Mustang Ram Air plenum actuator example. Using a no longer available repro from NPD as a model, I took a snorkel actuator removed the tabs from the new actuator base and made a new base from sheet metal with the correct tabs needed for the ram air plenum. I then glued the new base to the new actuator with body glue. I then finished it in yellow chromate although the originals were mostly silver.

[Brian Conway 244]

... and then there's this nifty little must have vacuum tester

[Past Time 3]

Wow, some great information here. Thank you for taking the time to post this. And yeah mine's garbage.

[JayEstes 157]

Man, that really is some great feedback.  I love when guys that have plumbed the depths of the rabbit hole wrap it all up for ya.  You deserve an award for that Rich!