'72 wiper door wierdness
Thread Starter
Cruising
Joined: Apr 2018
Posts: 10
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'72 wiper door wierdness
Still sorting out the '72 and just recently the wiper door has a mind of its own. First, it started opening on cold startup and then would close in the first few miles. Now, it opens at startup and stays open. I can manually close it and it will stay shut for a while.
I tried the RH wiper door switch at the steering column, but it had no effect. Could a vacuum hose have fallen off during my first month of ownership. Can't find vacuum hose diagrams in either shop manual. Any ideas?
I tried the RH wiper door switch at the steering column, but it had no effect. Could a vacuum hose have fallen off during my first month of ownership. Can't find vacuum hose diagrams in either shop manual. Any ideas?
Team Owner
Joined: Sep 2006
Posts: 31,283
Likes: 4,373
From: Westminster Maryland
Hi g,
When the wiper door opens upon start-up but closes after the engine has been running for some period of time the cause is typically a leak in the small 'control' hose running to the vacuum relay, a poor connection at the relay, or a leak in the relay itself.
Do you have vacuum pump with a gauge like a mity-vac with which you can test the operation of the relay?
Do you have the GM 72 Assembly Information Manual (AIM) and the 72 GM Chassis Service Manual for your car?
Regards,
Alan
This is the sheet from the 71 AIM showing the placement of the various components of the wiper door vacuum system and also the typical hose routing.
When the wiper door opens upon start-up but closes after the engine has been running for some period of time the cause is typically a leak in the small 'control' hose running to the vacuum relay, a poor connection at the relay, or a leak in the relay itself.
Do you have vacuum pump with a gauge like a mity-vac with which you can test the operation of the relay?
Do you have the GM 72 Assembly Information Manual (AIM) and the 72 GM Chassis Service Manual for your car?
Regards,
Alan
This is the sheet from the 71 AIM showing the placement of the various components of the wiper door vacuum system and also the typical hose routing.
Last edited by Alan 71; May 6, 2018 at 02:43 PM.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
The reason the door is raising up is that you are NOT having a constant good vacuum supply being on the small hose that goes to your actuator relay.
SO...in order to keep the wiper door and headlgith doors down...vacuum MUST be on the small hose going to the actuator relays.
You can easily have one problem that can fix it...or it can snowball on you where you have numerous problems.
The emergency override pull down switch under your steering column is there...so...when you pull it down it STOPS the vacuum supply...which will cause your wiper door to go UP. Pulling down on it is not doing what you want to do.
Reading what you wrote. I feel you had a problem that finally got so bad...that the door would not go down in a few miles of driving.
DUB
SO...in order to keep the wiper door and headlgith doors down...vacuum MUST be on the small hose going to the actuator relays.
You can easily have one problem that can fix it...or it can snowball on you where you have numerous problems.
The emergency override pull down switch under your steering column is there...so...when you pull it down it STOPS the vacuum supply...which will cause your wiper door to go UP. Pulling down on it is not doing what you want to do.
Reading what you wrote. I feel you had a problem that finally got so bad...that the door would not go down in a few miles of driving.
DUB
