After changing all the hoses,and replacing the check valve and filter ,headlight switch my headlights are still slow and will not open after the engine is shut off.Tested the vacuum tank and it dose hold a vacuum,the actuators also tested good .The vacuum drops like a rock in the manifold as soon as the car is shut down.My question is that on the relay I read to clean the filter ,where is the filter? on the relay?or was the artical refering to the in line filter near the vacuum source?I haven"t pulled them out yet and tested them yet,as it looks like a real pain.Has anyone ever rebuilt them?Or should I try to rebuild them myself?Or just order new ones?Anyone ? :confused:

 

Did you think about a leak in the boots on the vacuum actuators?

 

They both tested out OK

 

You can't rebuild the vacuum relay. You can't take it apart without destroying the metal collar that holds it together. The 1/2" filter in the end of the relay is only there to keep the chickens out. Don't bother replacing it, it will not make any difference.

The light switch (or the override switch) provides/prevents vacuum to/from a diaphragm in the relay (thru the 1/4" white striped hose) . This diaphragm moves a dumbell shaped rubber shuttle back & forth in the tubular section of the relay. In one position, the shuttle connects the canister vacuum (yellow stripe) to the hose connected to the rear of the headlight door actuator (red stripe) and the door closes. In the other position, it connects canister vacuum to the hose to the front of the actuator (green stripe) and the door opens. This rubber shuttle begins to leak after age. When it leaks, you can't get proper manifold vacuum. And, they may leak in either open or closed position.

I tried every solvent in my garage to "swell up" the rubber and reestablish a seal. Nothing worked. I've got a box full of used relays from swap meets. They all leak (even though I thought I tested them at the meet).

68 & 69 used one relay for both headlights. 70-82 used two. They're in the nose between the headlights. The relay inside the right fender for the wiper door is identical. With some tees and hose, you can re-plumb a two relay setup to operate with one (and still return to two later).

You can test the relay with a vacuum source, some hoses, and a guage. Apply vacuum to the center port on the relay. With no vacuum to the diaphragm, you should read full vacuum in the port furthest from the diaphragm. With vacuum applied to the diaphragm, you should read full vacuum in the port closest to the diaphragm. Anything less than full vacuum indicates a leak.

Your Chevy parts man will be happy to special order these at $80.00 each. Last year, ZIP had 9 in stock at the same price. This is one of those things where you got to bite the bullet and buy them. If one leaks, lots of other things will not work correctly.

 

Thanks for detail response I just tested them and found the bad one,You indicate that there still a stock item with GM dealer? Or there restro service? Any part number{Iknow I'm asking alot} I'm going to bubba it to one relay for now....love to be able to open and close them with the engine off,as no one at cruise night has been able to do this in my area :chevy

 

Thanks alot bubba65,if you want to swell up rubber you might want to try brake fluid just be carefull around paint :chevy I"m going to try this once I pull it out as I have nothing to lose :cheers:

 

One way of rebuilding them is described in the technical section at my page.
No leakage after one year of use.

 

Sorry, didn't record the GM part number, but the parts counter man had no problem lookin them up. ZIP part number is HDL-111

Tried the brake fluid. didn't work. Neither did gasoline, kerosene, acetone, dichloromethane (paint remover), carb cleaner, trans fluid, power steering fluid, alcohol, benzene, trichloroethane (dry cleaning fluid), methyl iso-butyl ketone (MIBK), methyl ethyl ketone (MEK) (both are catalysts used in plastic and rubber manufacturing). Even packed them with vacuum grease.

 

They WORK going to pull the relay latter...I can open and shut now twice with the engine off WoW :cheers:

 

I went with tie one relay setup. Dem suckers r expensive. :crazy:

 

Ingar, thanks for the link and "HOW TO" information about rebuilding these relays. I love fixing parts that weren't meant to be repaired!

(edited to add link) Ingar's web page showing how to do the rebuild http://iotech.no/corvette/technical/...ight_relay.htm



[Modified by MIKER, 10:03 PM 9/9/2001]