Confused by vacuum pump wiper...
June 12th, 2010, 06:04 PM
#1
Registered User
Thread Starter
Join Date: Aug 2009
Posts: 333
Confused by vacuum pump wiper...
I've searched the threads, but can't find an answer to this question.
1953 Olds 88, original interior, 1965 Olds 425 engine.
If I've read all the relevant threads correctly, the vacuum hose arrangement for the wiper motor has a single hose connected to manifold vacuum, the port on top of the wiper motor. The port on the bottom of the wiper motor is not connected to anything (which doesn't make sense to me, quite. I understand that if it were connected to vacuum, then the motor would simply lock up due to equal opposing forces. But doesn't leaving it open just create a vacuum leak?).
The vacuum line originally went both to engine manifold vacuum and to an auxiliary source at the fuel pump. (Obviously, since I no longer have a 1953 engine, that is not an option. It was only to maintain wiper function under low engine vacuum conditions, at any rate - as well as to ensure brake booster operation.)
My question: With a strong source of vacuum, the wiper motor rotates in one direction for a short distance when the switch is opened. Then it stays there until the switch is closed, at which point it returns to rest.
I actually have two motors - the original, which is slow and weak, and a replacement which is fast and strong. Both of them do the same thing.
The dash-mounted switch has two ports on it, but I have been thinking that those ports are solely for operation of the fluid reservoir; the only time those ports are active is when the push-button is pressed for wiper fluid.
I've tried the motor off the car and on the car, with no difference. Installed, the wipers move up when the switch is opened, and stay there until the switch is closed, at which point they return to rest.
What's going on? The shop manual is no help whatsoever. No diagrams, beyond one that helpfully points out where to remove two screws that hold the motor in place, as if anyone would be unable to find them.
Could both motors be bad somehow, in the same way? My hope is that I simply need to plumb the lines differently, somehow. Any insight would be appreciated.
1953 Olds 88, original interior, 1965 Olds 425 engine.
If I've read all the relevant threads correctly, the vacuum hose arrangement for the wiper motor has a single hose connected to manifold vacuum, the port on top of the wiper motor. The port on the bottom of the wiper motor is not connected to anything (which doesn't make sense to me, quite. I understand that if it were connected to vacuum, then the motor would simply lock up due to equal opposing forces. But doesn't leaving it open just create a vacuum leak?).
The vacuum line originally went both to engine manifold vacuum and to an auxiliary source at the fuel pump. (Obviously, since I no longer have a 1953 engine, that is not an option. It was only to maintain wiper function under low engine vacuum conditions, at any rate - as well as to ensure brake booster operation.)
My question: With a strong source of vacuum, the wiper motor rotates in one direction for a short distance when the switch is opened. Then it stays there until the switch is closed, at which point it returns to rest.
I actually have two motors - the original, which is slow and weak, and a replacement which is fast and strong. Both of them do the same thing.
The dash-mounted switch has two ports on it, but I have been thinking that those ports are solely for operation of the fluid reservoir; the only time those ports are active is when the push-button is pressed for wiper fluid.
I've tried the motor off the car and on the car, with no difference. Installed, the wipers move up when the switch is opened, and stay there until the switch is closed, at which point they return to rest.
What's going on? The shop manual is no help whatsoever. No diagrams, beyond one that helpfully points out where to remove two screws that hold the motor in place, as if anyone would be unable to find them.
Could both motors be bad somehow, in the same way? My hope is that I simply need to plumb the lines differently, somehow. Any insight would be appreciated.
June 13th, 2010, 07:05 AM
#2
Registered User
Thread Starter
Join Date: Aug 2009
Posts: 333
After spending 3-4 hours searching through various forums and search engines, everything I've been able to find indicates that yes, the motor should have just the one vacuum source, and the bottom port should be left open - and it should oscillate.
Many posts suggest that stiffness or lack of grease will prevent them from working, and I could see that for the weak pump I've got - but the replacement pump feels quite strong, and moves quickly.
Why do they both only move in one direction, not oscillate? Time to open one up and get a look inside?
Many posts suggest that stiffness or lack of grease will prevent them from working, and I could see that for the weak pump I've got - but the replacement pump feels quite strong, and moves quickly.
Why do they both only move in one direction, not oscillate? Time to open one up and get a look inside?
Thread
Thread Starter
Forum
Replies
Last Post
ukoldsrocket88
Other
11
June 14th, 2015 03:18 PM
