The Ford Barn

mleder · 07-10-2016, 08:45 PM

If I'm not sure that my vacuum wiper motor is operating correctly one of the first tests I'd like to make is take a vacuum reading at the connection to the wiper motor and then know if I have the pressure. If I do have the correct pressure then I guess the wiper motor would need to be serviced. What pressure should I have at various engine speeds. Say idle, 1/4 throttle and 1/2 throttle under no load? . Just looking for an approximate value.

Cool Hand Lurker · 07-10-2016, 09:54 PM

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Normal operating vacuum is 15-18 but when you press down the accelerator then vacuum drops to near zero until the engine picks up speed and you back off the accelerator. Then the vacuum will go back to normal. During that time the wiper will stop moving. You could put an accessory vacuum tank to store vacuum for those down times.
Other than that I don't know if it is possible to answer your question of relating vacuum to 1/4 or 1/2 throttle. You could assume that it is a normal 15-17 without the throttle moving or just take it on the road with a vacuum meter attached and go through the various speeds. That would give you a good idea of just how a vacuum wiper works also.

07-10-2016, 08:45 PM	#1
mleder Senior Member Join Date: May 2010 Posts: 179	Vacuum wiper and vacuum If I'm not sure that my vacuum wiper motor is operating correctly one of the first tests I'd like to make is take a vacuum reading at the connection to the wiper motor and then know if I have the pressure. If I do have the correct pressure then I guess the wiper motor would need to be serviced. What pressure should I have at various engine speeds. Say idle, 1/4 throttle and 1/2 throttle under no load? . Just looking for an approximate value.

07-10-2016, 09:54 PM	#2
Cool Hand Lurker Senior Member Join Date: May 2010 Location: So Minn Posts: 1,565	Re: Vacuum wiper and vacuum Sponsored Links (Register now to hide all advertisements) Normal operating vacuum is 15-18 but when you press down the accelerator then vacuum drops to near zero until the engine picks up speed and you back off the accelerator. Then the vacuum will go back to normal. During that time the wiper will stop moving. You could put an accessory vacuum tank to store vacuum for those down times. Other than that I don't know if it is possible to answer your question of relating vacuum to 1/4 or 1/2 throttle. You could assume that it is a normal 15-17 without the throttle moving or just take it on the road with a vacuum meter attached and go through the various speeds. That would give you a good idea of just how a vacuum wiper works also.