The Stovebolt Site Forums The Shop Area General Truck Talk Tech help need for vacuum wiper motor

I'm trying to get my windshield wipers going and not having much luck. The truck is a '57 3800 with only 29K miles so the wiper motor shouldn't have much wear on it. The truck had set up for some time so the rubber lines were gone. I took the motor and switch cable out and freed up the cable. I hooked the motor up to the vacuum line and it worked but stuttered a little right in the middle of the stroke. I took it all apart and cleaned it up and replaced the petrified grease with new grease and reassembled it. Now it will only move a little and won’t keep cycling. It always stops right in the middle of the stroke. If I actuate it by hand I can feel that it’s a little tighter in the middle but not a lot. I took a wiper motor out of a parts truck I have and went through the same process with it. It will cycle but seems much weaker in the ccw direction than in the cw direction. If I put a little pressure against it in the ccw direction it will stop in the center of the stroke and will not restart. Are there any tricks to getting these things to work properly? I have a double action fuel pump so I should have enough vacuum to do the job. If anyone can give me some advice or point me to a tech article on these motors I would appreciate it. I’d like to keep the vacuum motor if I can make it work right. Thanks.
Jeff

You might add a little oil to the paddle inside, your grease may not have soaked into the leather enough to soften it up. Make sure the trip valve is working right and try it on a new car or vacuum pump. They are pretty simple and not much goes wrong other then drying out.

Joe

Look at my Photo bucket pics I rebuilt a few and there all working good.

Pete

What grease did you use? I used Vaseline petroleum jelly in mine (got the tip from Wiperman, IIRC). Are you bench checking it or doing a test after it is assembled? Reason I ask is that mine doesn't flap very well with the blades on a dry windshield. No problem with a wet windshield.

Did you put in a new cotton filter? Mine was pretty gummed/dirty. If it is dirty, I suppose it could act like a plug. Also, if the gasket looks like it is 54 years old, you might have some leakage there. It needs to have a good seal to work well.

Finally, where the paddle swings, what does the casting look like? Is it scored from abrasive particles/petrified grease grinding away at it? I think you'll have better operation if the swing region that is in contact with the flap is smooth. It is possible there is some scoring that is slowing down the mechanism- if so, I'd polish it out with wet sand/rubbing compound.

Like Joe H said, these things aren't too complicated. The problem and solution hopefully are right there in front of you.

Alternate resources:
http://www.tbirdranch.com/wipmtrep.html
http://home.comcast.net/~sday77/binky/repair_vac_wipers.htm


Good luck.

Bill

I used whatever grease is in my grease gun, nothing special. I'm checking it by just hooking the vacuum hose to it while the engine idles and I hold it in my hand. It's not hooked up to the wipers. The filter wasn't dirty, but I tried removing it and it didn't make a difference. The inside of the casting, on one side near the middle showed signs that it was rubbing more there. I assumed that was causing the tight spot. I used some 1000 grit paper on it and it seemed to be smoother when I actuated it by hand. The gasket was broken in a couple of spots so I used some permatex on it when I reassembled. The 2nd motor from the parts truck worked better after it had the new grease in it for 24 hrs. Maybe it takes some time to recondition the paddle. The next time I have an opportunity to work on it I'll try some vaseline. These really are quite simple and ingenious at the same time. I had no idea how it worked until I took it apart. Thanks for the advice.

If I may make an observation, I think your grease is too heavy. One place I came across (I think it was wiperman, but I couldn't find it on his site yesterday. I'm not sure where I stumbled on the tip.) said to use Vaseline. Another said to use silicone grease. I've used silicone grease before on O-rings used in vacuum bells. The consistency is a lot like Vaseline, maybe a little bit stiffer but not much. The plumber's silicone grease I got at Home Depot over the weekend is very similar to Vaseline.

The grease in my grease gun is probably around 140 wt, MUCH higher than the clear greases.

I think you're on the right track as far as everything else. You made the paddle path smooth, you've sealed the "can" at the gasket, you've check the filter. I bet replacing the grease will get you in flapping.

By the way, if you aren't getting smooth action on the bench, it will be even worse when you hook up the linkages and arms. Don't bother reassembling until you get smooth action on the bench.

...and speaking of linkages, use that grease gun or lithium grease to lube up the joints/attachment points from the motor to the arms. They need lubrication too, to allow smooth operation.

Bill

Thanks again for the help. Hopefully I'll get a chance to try it again this weekend.

Jeff

I know you haven't reached this stage yet but try Rain-X on the windshield after you install-- it does help wiper action.
Good luck.

jfnar, I rebuilt my vacuum unit today thanks in large part to Pete52's photobucket pics. I hooked it to the vacuum line on my truck, and it tested great.

Here's the important part: Before I installed the vacuum unit, I tried moveing the wiper arms through their normal range of movement and found that the driver's side had a stiff spot right in the middle of the swing. The passenger side would hardly move at all. Now if I had installed the vacuum unit, I would have suspected that the unit itself was not working right.

So check to see if your wiper arms move smoothly, especially if the truck has set for a few years, or the wipers havn't seen much use.

Well, I got my motors reassembled with vaseline and they worked better. I installed the stronger of the 2 and put on new wiper blades and cleaned the windshield with Rain-X. The wipers work but just barely. They seem to be sticking right in the middle. Moving them by hand before I installed the motor, I didn't notice any tight spots but they are a little stiffer than I expected. I checked the vacuum on the line and it's getting 23" Hg. I guess I need to disassemble the wiper linkage and see if I can lube it up. I haven't had one apart before, are there any tricks to taking it apart? If this doesn't work, I guess the next step is to send one of the motors to Wiperman for rebuild.

Spray some water on the windshield while testing. They really only need to work when it's raining. If they almost work dry I bet they'll be fine wet.