68-72 HL/WW vac sys performance

[Rich D.]

Hi, folks. Does anybody know if there's a certain amount of time that the 68 to 72 headlight and windshield wiper vacuum system is supposed to hold vacuum when the engine is turned off?

For years I've noticed the one on my 1970 only holds for about 1 1/2 minutes after engine shutdown.

The other day I had some garage time, so I grabbed my handheld vacuum pump and spent a few hours checking every actuator, tank, solenoid, relay and hose. I found the following leaky components: LH headlight relay, check valve, WW solenoid (behind dashboard), and WW actuator manual override plug.

Is the vacuum system integrity a PV test item, or do the judges merely verify the system's operation with the engine running? Does a properly functioning vacuum system hold pressure overnight, for days, etc?.

Thanks,

Rich

[Kenneth T.]

Re: 68-72 HL/WW vac sys performance

Rich,

Interesting question. My '71 windshield cover and headlights would operate for several minutes after shutdown when it was new. Now, if the engine is not running the old girl will not perform. Is time sequence judged, I don't know?

Ken

[Patrick H.]

Re: 68-72 HL/WW vac sys performance

My 72 will open the headlights a few hours after I shut it down. I think I've even had luck the following morning.

The system is all original, never serviced.

[Terry M.]

[Jim T.]

Re: 68-72 HL/WW vac sys performance

My 70 when new would raise/lower the headlights the next day after sitting overnight. Never tested the system when new more than one day later to see if enough vacuum was stored to operate the wiper door or headlights. Don't know when it started loosing stored vacuum.

[Rich D.]

Re: 68-72 HL/WW vac sys performance



Great call, Terry. I forgot to check the heater control!. And your're right - its leaking like a seive. Time to get my hands dirty again...

[Rich D.]

Re: 68-72 HL/WW vac sys performance

Thanks for all your input, guys. I now know I've got some issues with the system. I've already ordered replacment relays, check valve, and ww solenoid. My goal is to have the system hold vacuum overnight.

I'll let you know how I make out.

Good thing its tax refund/economic stimulus time. I've already started stimulating the ol' Visa Card.

[Rich D.]

Re: 68-72 HL/WW vac sys performance

Well, after replacing the check valve, three vacuum relays and the windshield wiper soleniod, the system holds vacuum at least overnight - but only if I disconnect and plug the heater control system. Both my heater and fresh air vent switches leak like seives. Oh, well...

[Terry M.]

Re: 68-72 HL/WW vac sys performance

If you want to improve the overnight performance you can add a vacuum relay from (perish the thought) a F*rd. I don't have a number, but I was told there is a vacuum relay that is closed when no power is applied used on those products. This relay can be hidden in the center console and wired into the ignition.

I would suggest you work at fixing the heater control though. In the long run the engine will run better without that vacuum leak.