Weak Wiper

shew01

shew01

Well-known member
I got caught in the snow while driving my Model A this weekend, and my vacuum wiper was not up to the task of clearing the windshield. It’s always been weak since I bought the car a couple of years ago, but this time it couldn’t clear the snow flurries on the windshield at all. So, the flurries just bunched up on the windshield and turned into ice.

At this point, I don’t know if I have a leak in the line from the intake manifold, or if I have a bad wiper motor. I searched on this site, but I didn’t find anything useful for debugging this issue.

I don’t know much about the vacuum system. Can anyone give me some ideas how and what to check? Thanks in advance.


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The link below shows how to add light oil to the wiper motor. Basically you put the vacuum line in some oil and suck it into the motor by moving the wiper back and forth. There are also some discussion about the different vacuum motors and overhauling them.

http://modelabasics.com/wiper.htm

Don't use WD-40 as it will eventually evaporate. 3 in 1 oil is what I would use. If this does not work, look for where the air enters near the on/off valve, not where the vacuum fitting is, and squirt some light oil in there while it is operating.

If oiling fails you will have to take it apart and overhaul it. There are instructions on the web or you could send it to someone.
 
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The vacuum wipers are problematic, why they used them up into the 60,s on some cars, Rambler was one , stop going uphill or passing, in super sonic mode down hill. Had a 41 Packard that had 2 speed electric that actually worked so even then the technology for electric wipers existed.Sometimes if you have a reserve tank may work better, My roadster was fitted with an electric, but that small wiper blade on flat windshield isn’t the most efficient setup. Most people use a Rain X , that helps.Not being used much probably adds to the problem.
 
I've used a 12" length of vacuum line (clear poly so you can see inside) filled with MMO and attached to the vacuum fitting. First, take off your vacuum line at the fitting and manually move the wipers back and forth. You will feel wiper is either blowing or sucking air at the fitting. Stop after a blowing movement and attach the hose filled with MMO. Then, with the far end of the hose uncovered, rapidly move the wiper all the way it will go. Put your finger over the hose end and return wiper slowly to the reverse position. Then uncover the end and rapidly move the wiper back through its sucking cycle. Do this several times until the hose is empty of MMO. You may have to do this 2-3 times. If this doesn't lube and seal the inards, you'll have to take it apart.
 
Electric is the way to go. The supply houses now sell a setup that still allows the windshield to open.
 
I am sure you have good reason to drive your A in the snow but You might also be concerned about the damage the road salt is doing to your car’s body.
 
McMimmcs said:
I am sure you have good reason to drive your A in the snow but You might also be concerned about the damage the road salt is doing to your car’s body.
Click to expand...


Re-read the post. I got caught in the snow. The forecast was for clear weather. I don’t intentionally drive the car in the rain, let alone in the snow.


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nkaminar said:
The link below shows how to add light oil to the wiper motor. Basically you put the vacuum line in some oil and suck it into the motor by moving the wiper back and forth. There are also some discussion about the different vacuum motors and overhauling them.

http://modelabasics.com/wiper.htm

Don't use WD-40 as it will eventually evaporate. 3 in 1 oil is what I would use. If this does not work, look for where the air enters near the on/off valve, not where the vacuum fitting is, and squirt some light oil in there while it is operating.

If oiling fails you will have to take it apart and overhaul it. There are instructions on the web or you could send it to someone.
Click to expand...


Thanks for the link. That looks very helpful. :-)


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gdmn852 said:
The vacuum wipers are problematic, why they used them up into the 60,s on some cars, Rambler was one , stop going uphill or passing, in super sonic mode down hill. Had a 41 Packard that had 2 speed electric that actually worked so even then the technology for electric wipers existed.Sometimes if you have a reserve tank may work better, My roadster was fitted with an electric, but that small wiper blade on flat windshield isn’t the most efficient setup. Most people use a Rain X , that helps.Not being used much probably adds to the problem.
Click to expand...


My dad had a 1966 Rambler Classic. As I recall, it had vacuum wipers. We thought it was neat because you could adjust the wiper speed.


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Oldgearz said:
I've used a 12" length of vacuum line (clear poly so you can see inside) filled with MMO and attached to the vacuum fitting. First, take off your vacuum line at the fitting and manually move the wipers back and forth. You will feel wiper is either blowing or sucking air at the fitting. Stop after a blowing movement and attach the hose filled with MMO. Then, with the far end of the hose uncovered, rapidly move the wiper all the way it will go. Put your finger over the hose end and return wiper slowly to the reverse position. Then uncover the end and rapidly move the wiper back through its sucking cycle. Do this several times until the hose is empty of MMO. You may have to do this 2-3 times. If this doesn't lube and seal the inards, you'll have to take it apart.
Click to expand...


When I get a chance, I plan to try this. Thanks for posting.


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My vacuum wiper function really improved after I did a valve job on my engine. Put a good vacuum gage on your vacuum port and check engine vacuum. Your wiper may be telling you something.
 
If your wiper is a slug a bug under normal conditions then it may need an overhaul of the flap seal and gasket replacement. If it functions normally during moderate temperatures then the problem could be the cold weather. Parts contract and stiffen in cold weather so that doesn't help function. If it functions better when you let off the throttle then the operator has to go under power for a bit then let off the throttle for a bit to clear the windshield. This has always been an issue with vacuum wiper motors. In later years, dual action fuel pumps were offered to boost the vacuum while the engine is under load. This helped quite a bit but these fuel pumps were an option and not standard equipment in more arid regions of the country.

As was mentioned, engine ring & valve condition can have an affect on the manifold pressure. Higher than normal manifold pressure would cause problematic wiper motor function.
 
Those wipers are awfully tricky...finicky tolerances...non-standard fasteners. I did the best to get mine working correctly, but had little luck. I ended up sending it out for a rebuild. That was twelve years ago and it still works great. I sent it to Ficken. The price was reasonable, and the turn-around time was pretty quick.

https://rebuildingtricowipers.com/

Ken
 
From what I have read and after talking with experienced "A"ers the vacuum wipers are best used as an ornament. Rainex is the way to go and I would assume that the Rainex would not allow the flurries to accumulate, but that's a guess as I have never driven my A in snow.
 
I thought I’d start testing at the easiest point. I didn’t know if I have a leak in the line between the intake manifold and the wiper motor; so, I connected a vacuum gauge at the wiper end of the line, and I am getting around 18 on the gauge. Here is a picture of it. I didn’t see a way to upload video. Does this look typical? The engine is cold. I don’t know if that makes a difference or not.

0afb67f6d14cf02bced777d774bc8e31.jpg



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Neal, Oldgearz,

I put some Marvel Mystery Oil in a small squirt bottle and blew a little into the wiper motor vacuum fitting, and I replaced the 3” long vacuum line between the wiper motor and the line that comes through the header. Wow. I have a wiper now (at least in the dry), although the wiper still may end up being mostly decorative in the rain. Lol

This a HUGE difference. Thanks for your help! [emoji3]


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