66 Toro headlight problem and diagnosis

Post your technical questions and information here.
sz3gfj
Posts: 11
Joined: Thu Aug 08, 2013 8:47 am
TOA Membership Number: 0

66 Toro headlight problem and diagnosis

Postby sz3gfj » Wed Jul 13, 2022 9:54 am

I’m having trouble with the vacuum operated headlights on my 66 Toronado. Maybe someone can help.

Current issues: Neither headlight raises when headlight switch turns to “on”. RH headlamp can be manually raised but does not lock. LH headlamp cannot be manually raised, it seems to be locked into position.

Headlights kind of worked for awhile (right side was lazy and wouldn’t go up all the way). Now they don’t raise at all.

I want to do some diagnosis to figure out what’s wrong. To get started, I need to know how the system is supposed to work.

After studying all the relevant postings, diagrams, etc. that I can find, here’s how I think things are supposed to work:
- Engine vacuum goes to a check valve (missing on mine, it was replaced with a tee. I found a vacuum check valve GM 15-50568 and relaced the tee, but saw no change in operation). I assume the purpose of the check valve is to maintain vacuum for awhile when the engine is off. Downstream of the tee, the vacuum goes to the vacuum reservoir tank and the vacuum source port on the headlamp switch.
- When the headlamp switch is ON, vacuum from the engine or reservoir goes to the headlamp switch and then to the vacuum actuators. The actuators in turn raise the headlamps, and there appears to be a mechanical latch which holds them in place.
- When the headlamp switch is in PARK or OFF, the vacuum is disconnected and the vacuum line from the headlamp actuators is connected to the latch controls. It appears that the vacuum in the actuators is sufficient to operate the latch control diaphragms, which releases the mechanical latches. For the headlights to retract, there needs to be a bleed-off of the residual vacuum, but it is not apparent how this happens. Could it be a small orifice in the headlamp switch, or is there leakage at the actuators or elsewhere? Some posts seem to say that the check valve provides the leakage but that does not seem reasonable.

Let me know if I don’t have this correct.

I want to do some vacuum diagnosis to see if I can isolate one or more issues. I tried using a Mytevac to generate vacuum, but couldn’t get enough vacuum pumping by hand. I’m thinking of using an electric vacuum pump to provide vacuum and to use a vacuum gage to monitor what’s happening. I would measure engine vacuum at idle and try to maintain that level. Is there a danger of damaging the vacuum actuators or latch control diaphragms with too much vacuum?

First step would be to apply vacuum from the pump to the vacuum line from the engine and cycle the system. I expect there would be no change.

Second step would be to apply vacuum to the vacuum tank to see if it holds vacuum. If it doesn’t, there’s a leak related to the tank.

Third step would be to apply vacuum to the vacuum actuator lines at the tee from the headlamp switch power port and see if the headlamps raise and latch. If both headlamps raise, then there is a potential problem with the headlamp switch. If neither headlamp raises, there may be issues with the vacuum hoses, tee, or connections. If only one headlamp raises (probably unlikely with current symptoms), there may be a problem with the vacuum actuator, its line or its connection.

Next step would be to check the latching mechanism. To unlatch, it would be necessary to apply vacuum to the latch control lines at the tee from the headlamp switch unlatch port hose. If the headlamps unlatch, there may be a problem with the headlamp switch. If one or both of the headlamps do not unlatch, there may be problems with the latch controls, their hoses or connections.

Finally, I could check the headlamp switch itself in a two step process:
1) Apply vacuum to the vacuum source line downstream of the check valve, and monitor vacuum at the power unit port and then the unlatch port. With the headlamp switch ON, there should be vacuum at the power unit port and no vacuum at the unlatch port. With the headlamp switch in PARK or OFF, there should be no vacuum at either of these ports.
2) Apply vacuum to the power unit port With the switch in PARK or OFF, there should be vacuum at the unlatch port but no vacuum at the vacuum source line.

Hopefully this process would help isolate the issues.

Please let me know what you think. Any other information, help, or ideas are welcome.

Kollege
Posts: 14
Joined: Wed Apr 17, 2019 4:53 am
TOA Membership Number: 1441
Years Owned: 1966 Toronado
Location: Germany

Re: 66 Toro headlight problem and diagnosis

Postby Kollege » Sun Jul 17, 2022 11:27 am

also had problems with my '66 headlights last year. both no longer opened. I would advise you to first check the vacuum hoses in the engine compartment for leaks. to do this, also pull off at each connection and look with your finger or better a pressure gauge (with the engine running and lights on or off) to see if you have negative pressure. during this procedure, my T-check valve broke. I replaced it with a Dorman 47150 (US$3).

then check the correct arrangement of the hoses (routing) according to the shopping manual.

the light switch itself can also be leaking. but I would first, if the hoses are ok, continue with the actuators. in my case they were the problem.
locate the short piece of hose coming out of the bottom of the actuator and connect a vacuum source directly there. if nothing happens, you will have no choice but to open it. to do this, remove it, drill out the rivets on the top of the cover, and look inside. Be careful, there is a spring inside which is quite strong. in my case the inside was still intact but the disc has no longer sealed properly. I have everything cleaned and derusted, the rubber disc one week soaked in brake fluid and then the flanks well greased with silicone grease and everything reassembled. Instead of the rivets I have taken screws with self-locking nuts. of course edit both actuators ;-)

User avatar
Otto Skorzeny
Posts: 1721
Joined: Fri Feb 28, 2014 12:41 pm
TOA Membership Number: 0
Years Owned: 1966 Toronado

Re: 66 Toro headlight problem and diagnosis

Postby Otto Skorzeny » Wed Jul 20, 2022 5:16 am

Fortunately my headlights worked correctly so I didn;t have to do much digging into the system but I did have a minor problem when I first bought the car.

The driver side light would not go down. The latch can be mover with a long screw driver. As it turned out, the T underneath the reservoir was leaking.

If your actuators are leaking or rusted, there is a post on this sight with photos and descriptions of a repair in which new parts are made with a #D printer.

The plans for the #D software are also posted.

Willysnut1959
Posts: 107
Joined: Sun Dec 16, 2018 11:01 am
TOA Membership Number: 0
Years Owned: 1966 Toronado

Re: 66 Toro headlight problem and diagnosis

Postby Willysnut1959 » Fri Aug 05, 2022 10:40 am

I encountered similar problems with my "66 lights. Replace each hose section with new, rebuild both vacuum cannisters (conical spring and corrosion is suspect), and diagnose the little check valves to see that they are working.
Marty


Return to “Technical Talk”

Who is online

Users browsing this forum: No registered users and 15 guests