Mac78and2K

On my 78, after ideling for several seconds, i can turn my lights on (or activate the manual overide switch under the steering column) and the lights "pop" up fast and hard. When I turn them off, they go down very fast. If I try to turn the on again immediately, they are very slow to come up...VERY slow..... I turn them off, idle for about 5 seconds, and they "pop" up immediately. The car has a slight miss like there is a vacuum line loose somewhere, but I cannot find it.
It seems like there is a vacuum resivoiur that is leaking down and not building up fast enough to raise the lights immediatly after turning them off.

Any suggestions????

Berserker78

I had a similar problem, caused by a leaking vacuum filter. The way to check and see if you have a leak is to run the engine for about 2 minutes, turn it off wait 10-15 sec, then try to raise the lights. If they come up, then you do not have a leak.

Beyond that, I couldn't help you


[Modified by Berserker78, 11:58 PM 1/3/2002]

Warren77

I fought my 77 for a bit and have claimed victory. The best advice i ever recieved for vacum trouble was this. with your car off, remove the vacum line from the manifold. Get someone to watch and blow smoke into the vacum line and wait for the leak to show its self. If you dont smoke get a cigar.
It worked for me.
Good luck.

Mac78and2K

Thanks for all the help. I let my cat sit for 2 seconds (not running) and the lights will not come up. Sounds like the vacuum filter is leaking. Where is it located?

Rexx

I think it is that little dohickey :conehead coming off the break booster. It has two hoses in it -- one running in and another running out. It just hangs there by its hoses not too far away from it the oil filled cap on the valve cover. :D

good luck

:cheers:

Rexx

JB

On my '78, the filter is on the drivers side behind the carburator. It is in a vacuum hose that comes off of the fitting behind the carburator on the intake manifold. It looks like a white disk. It may well be your problem, but a leak anywhere would cause the same problem, I would think.

JB

'78SA

kenincanada

That test with the smoke is a good one. And if you used POT you could just smell for the leak

VegasJen

mac, your filter may be leaking but it sounds like a 'generic' leak that may not be the filter at all. the vacuum systems on the c-3 are prone to leaks from various places. first off, the vacuum feed line on your '78 should come off a fitting located just between the distributor and carburator. when you remove your air cleaner and look at that area you should see something that looks like a hex head bolt with a tube coming off to one side. it will have a rubber hose attatched to it. that is where the headlight system receives its vacuum supply. about 6-8" from the fitting you should see a white-ish plastic peice about 1" in diameter, that is the filter. a couple inches past that is the vacuum check valve, it is diecast aluminum in appearance and has one hose on one side and two hoses on the other. it's very likely this could be your problem as well, especially for the problem you are describing.
with the engine running, take a pair of pliers (preferrably ones with a smooth finish in the jaws) and crimp the hose as close to the manifold fitting as you can. if you notice a difference in the engine idle, you have a leak. if you determine you have a leak, perform this test after every major component to determine what section of the system is leaking. i don't claim to be an expert on these vacuum systems (yet) but i'm working on it, anybody have any other hints i'd love to hear them.
BTW, for anybody interested--vacuum relays are rebuildable. ask me how!