Vacuum Cannister Problem....Grrrr! (1982)

[KikiPhillips]

Ok....I borrowed a "Vacuum Puller" from my Dad, You hook an air compressor to one side and it draws 29.9 on the other end. I used it to test each of the 4 vacuum lines on the A/C control switch inside the car and everything open correctly.

So, I checked my source, from the little T connector where one end is connected to the Intake and the other goes to the vacuum cannister in the very front between the headlight actuators. And it is not drawing at all from the cannister. My headlights open and close properly but there is nothing drawing on that one line....

Any ideas or tricks to test, without replacing that cannister??

 

[Vettehead Mikey]

I didn't think the canister mounted between the headlights (not enough room) but are you saying there's no vacuum at the line you're testing, or the canister won't hold a vacuum?

 

[KikiPhillips]

Yes there is a cannister in the very front between the lights, right in the middle, very easy to see and reach. It has 3 output stems, two large ones that go to their respective lights and one medium size that goes straight to the T connector, one side goes to the Intake and the other reduces down a bunch and connects to the source for the interior A/C / Heater Control.

I assume the cannister works because the Lights function properly. But the middle medium sized stem is not sucking any air at all.

How is the vacuum created on that cannister? I always thought from the intake?
Also, How in the Hell does the two large lights work and the smaller line not work at all?

Any Answers, Insight and What-about-this's are most welcomed...

 

[Vettehead Mikey]

I assume the cannister works because the Lights function properly. But the middle medium sized stem is not sucking any air at all.

How is the vacuum created on that cannister? I always thought from the intake?

I wouldn't assume anything about any component. The middle line should show vacuum equivalent to that seen directly at the intake manifold source.

Here's a test- try raising the lights an hour or two after stopping the motor. If they don't snap into position immediately, there's a significant vacuum leak somewhere.

 

[73shark]

Have you checked the hose to verify that it's not clogged?

 

[Antz81]

Odd sounding vacuum tester, does it allow you leak test an item or does it just create vacuum?

Vacuum is created in the canister from the line you have traced back to the tee piece. So if you don't have vacuum on this line then you'll need to check it for blocks or breaks.
also just because your headlights work doesn't mean things are right. The seals on the actuator rods can be completely gone and they will still go up and down.

 

[KikiPhillips]

The is not clogged, air flows freely through it. I did try something: I put a cap on the T , cutting off the line that goes to the canister and also, plugged the line to the canister and the Flaps inside the car started working properly. The lights still function properly. So it seems to be a fix or work around.

It makes me wonder what the hell is up with the canister? Could that one line be messed up? Without messing up the vacuum for the lights?

The only problem I have now is the A/C switch, when I put it on "Normal" the fan stops blowing. But "Max" works fine. Plus, all the others work correctly now. Defrost, Vent, Heat.

Thanks for all the great feed back....Let me know if you have an idea about the "Normal" not blowing...

 

[bill81vette]

check your vacuum lines in the dash and make sure mickey hasn't made one of them a snack!!!

 

[Antz81]

As Bill said above, plus check all your other lines to your headlights to make sure mickey (or bubba) hasn't found any of them.

As for the blower not working on normal, you put a new switch in here just recently didn't you? if so there shouldn't be any problems like that. The switch is the only thing that could do that. (at least consistently on the same setting)

 

[Vettehead Mikey]

The is not clogged, air flows freely through it. I did try something: I put a cap on the T , cutting off the line that goes to the canister and also, plugged the line to the canister and the Flaps inside the car started working properly. The lights still function properly. So it seems to be a fix or work around.

It makes me wonder what the hell is up with the canister? Could that one line be messed up? Without messing up the vacuum for the lights?

The only problem I have now is the A/C switch, when I put it on "Normal" the fan stops blowing. But "Max" works fine. Plus, all the others work correctly now. Defrost, Vent, Heat.

Thanks for all the great feed back....Let me know if you have an idea about the "Normal" not blowing...

Isolate the canister from the rest of the system. Does it hold vacuum?

 

[KikiPhillips]

Okay...I made a mistake, the headlights do not pop up now. So the plugging this and that only made the interior controls work.

So, the bottom line is, the vacuum on the canister in the front is created from the intake manifold, but it's not enough to work the canister and work the interior A/C controls....

So how do I get more vacuum power?

I did find out that the Check valve is not working, it's like a whistle now, you can suck and blow through all 3 lines....I'll buy a new one...would that create my vacuum deficiency?

 

[Antz81]

The check valve just keeps vacuum to the headlights and ac system after to engine is shut off. (assuming no leaks in the system) You do need to replace you check valve it if not doing this as you say, but it wouldn't be the cause of the problem you describe.

From what you have said though it sounds like there is a leak(s) at your headlights somewhere. You will need to check each part and line one by one until you've found them all.

One common place that's often overlooked is the rod seals on the headlight actuators since the headlights will open and close fine even if these seals are leaking. (or virtually nonexistent as mine were)

 

[Vettehead Mikey]

From what you have said though it sounds like there is a leak(s) at your headlights somewhere. You will need to check each part and line one by one until you've found them all.

Starting with the canister as requested above.

 

[KikiPhillips]

Great advice yall, I went ahead and pulled the canister and noticed a decent sized rusty crack in it, as well as another little hole. Son of Bitch!!! huh?

Being a do-it-yourselfer kind of guy, I sanded it down to bare metal and put JB Weld on it. Just to see if it fixes it, instead of spending $50 bucks on a coffee can. I can always buy one.

I'll let you know the outcome, soon....Thanks again..

 

[KikiPhillips]

Back in business, the JB Weld worked like magic. However, I still have the A/C issue, with the blower stopping when I put it on normal. I'm going to start a new thread. Please respond.