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I am hoping that someone can point me on the right track to troubleshoot my wiper door.
If the engine is running it operates exactly as it should. If I turn off the engine it stays closed for between 1 and 2 minutes. At that point you can hear the vacuum release all at once and the door opens.
I would be grateful for some direction on the correct troubleshooting thread/video or any help in general.
I do have a vacuum pump and have already diagnosed a bad check valve that’s been replaced.
Last edited by abusfullofnuns; Jun 29, 2022 at 06:43 PM.
Reason: Title
This thread helped me understand the system. Good luck, more info will surface. . Post #4 especially
Also check the override switch in the cockpit. I keep thinking as I sit here ( probably weakening the Nation! ) Ha Ha
This thread helped me understand the system. Good luck, more info will surface. . Post #4 especially
Also check the override switch in the cockpit. I keep thinking as I sit here ( probably weakening the Nation! ) Ha Ha
Thanks for that link. That was a very informative post. The hoses have all been replaced with new and seem tight. From that explanation I think I know what to check and I’ll post the results as work through the system.
Thanks for that link. That was a very informative post. The hoses have all been replaced with new and seem tight. From that explanation I think I know what to check and I’ll post the results as work through the system.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Whats happening is you lose vacuum on your switching side first so the actuator relay releases the valve which is spring loaded and you can probably hear that leaking. Once all the vacuum holding that spring back is gone the actuator pulls vacuum on the opposite side and the close side is vented. I would use a hose as a stethoscope and when you shut off the motor i would listen to the actuator relay. On a 69 it should be right on the firewall by the wipers or by the brake master.
Get an assistant to shut off the car while you are ready to pounce on the relay with your stethoscope or use the palm of your hand to choke the carb so you are right there and dont lose any time.
I use an AC vacuum pump on a remote switch and a really long hose to test my setup
I had this same issue and decided to resolve it this past winter. Short story is wiper arms were being pushed down when wiper door was closed and with car running with vac closed nicely. Car off, few minutes later door rises up 1/4 inch. After extensive parts replace and adjusting, determined wiper arms were like springs pushing door open. Had wiper door on and off probably 10 times. Wipers adjusted per AIM, then used all the adjustment to push arms down as far as possible, still hitting. My wiper arms are NOS GM replacement, and my understanding is they may not be exactly the same as original 1969. Ended up trimming the forward rib on bottom side of wiper door with Dremmel tool about 1/2 inch deep x 4" long to provide clearance foe wiper arms. Wiper door stays down perfectly now. I took some pictures of trim, will find and post soon.
getting closer to narrowing it down. I found an old corvette central troubleshooting guide that cleared up my confusion. Not sure if it’s available here or anywhere else but it’s got good diagrams and info.
After reading the article and diagrams, I’ve narrowed it down to the control line going to the actuator or the manual valve. I clamped the control line at the actuator and it’s stayed closed. I believe this is what @Rescue Rogers was trying to tell me. I wasn’t quite ready to understand yet. My issue is between these two points.
Family is hassling me for dinner, so I’ll have to confirm the rest tomorrow.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
great!!! you found the issue that causes the symptom. Now you need the cure. Simple steps with the least amount of effort to the bigger pains in the but is the route I like to take. THe simplest way to do this is Just move your clamp to the other side of the override switch and see if you still have the issue. Keep working your way back until the issue shows up and the component or hose connection that you last bypassed will be your leak.
More testing and I believe I have arrived at my issue.
Clamped at the override and it stays closed. Upon inspection, the wiper override looks original. It’s chalky compared to the headlight side. I also pulled the boot and connected directly to the override. In this scenario, the wiper door still raised. Looks like I will order a couple override valves and go from there.
Thanks for the hand holding. I should be good on the vacuum systems now. Having fun with learning the intricacies of this car.
I’ll update this thread to close the loop once I’ve got the override. Feeling good! 😂
😂 not as smart as I thought I was. I should have done some more testing because the override valve was not the problem. It needed to be replaced because it was not smooth but didn’t solve the problem.
I’ve moved upstream and pausing to regroup for a minute. Clamping either side of the override will prevent it from raising the wiper door. Either side of the wiper solenoid will keep it closed too. I’ve worked my way to the T that goes to the headlight switch and the manifold vacuum check valve. Green check mark indicated clamping worked. Clamping the headlight switch side of the T causes the headlights to raise. I’m guessing that behavior is an indication of a problem but need to think it through some. I’m a little confused as to why I don’t have an issue with the headlights raising if the problem is on the headlight control side.
More testing. The red x being clamped causes both the headlights and the wiper door to open almost immediately. The blue check causes the headlights to open and eventually the wiper door to open a couple minutes later.
Might be a bit of a long shot, but the vacuum relays have a vent port to atmosphere on them that bugs just love to build nests in and clog them up.
I think I’m good there but I’ll keep it in mind.
For fun, I clamped each side of the headlight override. The purple X did not solve the wiper door open condition. The yellow X opened both the headlights and wiper door almost immediately.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
when the control side of the vacuum actuatoir relkay looses vacuum, the plunger will move from closed to open. If you clamp something and the door opens immediately, that means the vacuum on the other side vented immediately. Do you have a vacuum tester like a mighty vac or just a vacuum gauge. can you unplug the blue check mark hose and use a small hose to cap that side of the T? It will eliminate the headlight side and you can concentrate on the wiper door side only or plug a vacuum gauge into the blue side to see how fast you are loosing vacuum.
If you clamp the red check that means you are cutting off the vacuum tank and any leak is immediately loosing all the vacuum since the tank can not compensate. You might have a leak at the tee or somewhere in the portion of the blue side or you have a leak at the one way vavle and its leaking back into the manifold.... clamp the line coming from the manifold and see what happens
when the control side of the vacuum actuatoir relkay looses vacuum, the plunger will move from closed to open. If you clamp something and the door opens immediately, that means the vacuum on the other side vented immediately. Do you have a vacuum tester like a mighty vac or just a vacuum gauge. can you unplug the blue check mark hose and use a small hose to cap that side of the T? It will eliminate the headlight side and you can concentrate on the wiper door side only or plug a vacuum gauge into the blue side to see how fast you are loosing vacuum.
If you clamp the red check that means you are cutting off the vacuum tank and any leak is immediately loosing all the vacuum since the tank can not compensate. You might have a leak at the tee or somewhere in the portion of the blue side or you have a leak at the one way vavle and its leaking back into the manifold.... clamp the line coming from the manifold and see what happens
Thank you @Rescue Rogers for sticking with me. I do have a better version of a mighty vac.
I capped the blue check mark hose and the issues persist. I also clamped manifold side of the check valve, and still persists. I checked the T and it holds vacuum.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
you may have to disconnect the line on the red x side at the T and use the mighty vac and pull a vacuum on the system and see if it holds vacuum. THeres a leak there somewhere.
you may have to disconnect the line on the red x side at the T and use the mighty vac and pull a vacuum on the system and see if it holds vacuum. THeres a leak there somewhere.
Obviously you are correct.
Putting the vacuum pump on each part gave me different results than just clamping the hoses. The wiper door solenoid leaks. Unfortunate, because it has been recently replaced from the looks of it. This time I’m 100% sure. 😂 I suppose I should try to seal the hoses to the unit but doesn’t seem likely based on tightness. Have checked each hose independently.
1969 wiper door issue (going deeper)
. Post #4 especially
