My 72 Convertible has me puzzle'd on what maybe causing this to happen. A good friend of mine got the door to open and the wipers to function, but like the thread sez, on start up the wiper door opens and closes.

Without having to replace the entire vacumm system, would you all have any suggestions on what maybe causing this to happen?

It maybe something I might have to live with, owning a 36 year old car.

Thankx

Charlie
1972 Red Convertible
North Beach, MD.

 

Your losing vacuum in your system. Could be the check valve.

 

I'm fighting the same battle with my 69. I'll let you know when I figure it out.

 

My 68 does the same thing. I am doing a rewire, vac system is next. Will be interested to see what you come up with. I know one problem that I have is the vac canister. Read that it is tough to get out. Not looking forward to that chore.

 

The wiper door vacuum solenoid behind the tach is dirty or bad. Classic symptom. It needs to be replaced or taken apart and cleaned.
http://www.71corvette.com/wiper.html

 

I have to disagree with this being the problem of the door opening and closing on start up.Although cleaning it wont be a bad investment of time.
The door opening and closing just means that on start up the entire system has NO vacuum left in it.When there is no vacuum in the system the wiper door relay go to the "open" position-when the engine starts the vacuum builds and the first thing to react is the wiper actuator and the door pops up,then the vacuum builds enough to tell the relay to go to the "closed" position.This condition usually comes from a bad check valve BUT "any leak" that will bleed the entire system will do this.

 

My headlights and wiper door was doing the same thing last month. Process of elimination.
I new I and a bad manual override valve cause it wasnt there, so I got a new one and still had the problem. Checked the in line check valve and replaced cause I could blow thru it both ways.
I checked and replaced the grommet and check valve on the power brake booster as well. Dont think it effects the wiper/headlight but will be a cause to lose vacuum.
At this point the head lights were good to go but the wiper door would come up still.
Started searching again and found a lot of hoses that were bearly hanging off the nozzles of either the Tees and or the relay and or the valves.
I had read here to put a sealer RTV or RVT on the OUTSIDE of the nozzles/ nipples and attach the hoses & let dry make sure you cant turn the hoses as well.
If the ends of the hoses were wollered out or I could turn them easy I cut off the ends maybe a 1/2" if I had enough hose lenght.
All the hoses to the vac tank were all loose, and so were the hoses going to the wiper actuator on the fire wall.
After doing all of this and letting all the new sealed fitting and hoses dry everything tested fine on the second start up of the car.
I was getting ready to start spending a lot of money trying to fix a problem that wasnt there by changing out parts that cost a lot of dollars.
The over ride valve and check valve was right at $25.00 and I didnt have to gut the dash and or replace the entire vacuum system.
Just some ideas that help me fix my problem.
Hope it helps

 

This forum is such a great source for info. Thanks guys. I'm going to get this wiper door to operate correctly, if it's the last thing I do. Any other ideas? Thanks again.

 

Do this first before spending any money

 

Thanks for the link. It will come in handy some day down the road.

 

doc rebuild has a great trouble shooting paper

 

I have similar issues with my '75's headlights. I replaced a bad override valve and used some rtv to ensure a good seal. The problem is much improved.

I know for my headlights the other spot I need to hit is on the main switch in the dash. There are two halves to that switch and they don't hold their seal very well. So when I have time I'll pull that part of the dash and rtv the outside of the switch.


Look for loose hoses or hoses without a good seal and hit them with a little rtv.

 

You can disagree all you want I know when I had the same problem and someone pointed me to the link I provided I did it and it fixed my problem. This was the only thing I did to fix it too. So if you still disagree thats fine but I have pratical experiance and know what I'm talking about. Guess I'll go back to Vette***where experiance is appreciated.

 

Sorry-didnt mean to upset you.The condition I usually find when the vacuum solenoid is dirty is when you shut the engine off the wiper pops up right away.Reason for that is when the valve is dirty it is dumping vacuum all the time out of its dumping port.If the leak is very very slow it to will bleed the entire system.I'm not saying your wrong but that the vac. solenoid is not a common cause of the OPs condition.As I said before any leak that bleeds the entire system will do this.I find for that condition the most common problem is the 3 port check valve then the vac.valve under the wiper arm.In my 30+ years of working solely on corvettes I have replaced 1 vac. solenoid and cleaned 3.

 

For those of you that care here is a link to a check valve that will work in place of the original check valve.The repo original type valves are not the best,Ive had a few leakers.One of the ports on the 2 port side is too small for the larger hose,I just slide a small piece of tubing over the port to make it a little larger and it works great.
http://www.partsamerica.com/ProductD...goryCode=4016E

 

How does the vacume tell a relay to open or close unless it pushes a manual lever openor close which inturn feeds 12v+ or - to a relay?

Not questioning your answer just looking for a answer as I ripped off my crash pad to investigate.

 

The relay in this case is all vacuum.Its the same as the headlight vacuum relays.The relay has a diaphram mounted to the top of a valve.The diaphram moves a rod connected to the valve.
(You werent talking about the 12v vacuum solenoid were you?)