Vacuum Wiper Question--'50 Special

[beerczar1976]

I figured I'd try to get my vacuum wipers working now that I went thru the whole process of installing a new windshield gasket on my '50 Special...Yeah that was fun...  Put on new 7/32"id vacuum hose, connected up to the switch, wiper knurls turn in only one direction (opposite to outboard of car as they should), no return back to start position unless I shut switch back off.  Well after messing around with it, checking connections, etc., I finally pulled off the motor and opened it up.  It didn't really look all that well lubed, seemed a bit dry, had a little bit of gunky grease residue here and there, but really clean.  Based on internal cleanliness and overall look of unit on the outside, my guess is that at some point it may have been rebuilt.  Lubed it up, hooked it up to vacuum line, motor runs like hell when not attached to cowl.  Suffice to say when mounted back to the cowl it would run again in only direction only.  Pulled unit back off (kinda pissed at this point...LOL), added more lube (been using a combination of white lithium grease and brake fluid), unit on it's own still runs like a clock.  Mount back on to the cowl, this time wipers work beautifully.  Awesome, until I shut of car, and cleaned up work area.  Upon re-start, same damn issue, no wiper movement again...  I have not yet even bothered to put the actual wiper arms on the car, so it's not a dry windshield issue.  I don't think it's a vacuum pressure issue since when testing the wiper fluid it sprayed near clean over the roof of the car...plenty of pressure there.  I think my final question comes down to how tight should the under dash cable transmission set-up should be?  I did find initially that the external part was pretty tight to turn by hand and was kind of crudded up.  Somewhere in the past, car had been repainted and cowl was left in primer white.  The transmission area had been sprayed over and may have caused some binding due to paint, years of sitting, etc.  I cleaned all that best I could, and it now rotates pretty freely by hand.  Anything I'm overlooking?  I did see that their is an access plate on the transmissions where they go thru the bottom side of the dash on both sides of the car...maybe I need to try and lube in there as well?  Like I said, I did get the whole unit to run great for about 10 mins on it's own before I shut off the car that last time...  Very strange.  I did notice on other years that motors have rubberized mounting collars.  The '50 only has the diecast collars that accept screws that lead into the cowl.  Is there maybe supposed to be a spacer I'm missing?  Maybe with a spacer, there's enough offset that motor to transmission junction is not as tight?...

[Pete Phillips]

I would say lubricate every pulley and joint in the entire wiper transmission system. Use up half a can of WD-40, if that's what it takes. Make sure all of your rubber vacuum hoses are good and snug onto the metal ports where they fit, including at the fuel pump.

Another thing you could do is remove the wiper motor, install the wiper arms, dampen the windshield, and see how hard it is to move the wiper arms back and forth by hand. That would tell you if the linkage is the problem with it binding up somewhere.

[Bloo]

On my Pontiac, some DPO had put screws around the windshield trim that were about 3/4" too long and they were blocking the linkage.

 

If it is the wiper motor's fault, it has to be that either the flapper is leaking at that end, or the little reversing valve is not flipping over. Did you clean it out too?

 

 

[beerczar1976]

Yes.  Wiped it down.  Like I said, inside, was quite clean, figured it was going to be nasty in there.  Either still sealed up well from factory, or had been rebuilt.  I had somewhat similar issue with my clock too.  Wasn't working even with brand new wiring.  Took it out from dash, open it up and found inside to be near immaculate...couple drops of oil and away it's ticked and rewound the spring on it's own since then about 3 years ago.  I give it more of a go and try to add more lube to entire system...I had already tried the white lithium on a few spots on the transmission as well, but might not be hitting the right places yet.

[JohnD1956]

Have you put a vacuum gauge on the port to the motor, to see what the actual vacuum reading is?  And if it is steady or if it fluctuates?   If the wipers worked for 10 minutes once, then it would seem it's not the motor or the transmission hubs.   

[Bloo]

I was specifically referring to the piece in red (and the stuff underneath it) here. That is how the motor reverses at the end of the travel. Not the right motor in the pic, but they all have something about like that.

 

Edited August 27, 2019 by Bloo (see edit history)

[gdmn852]

Hello as mentioned in other post check all the cables and pulley,my 49 was binding up on linkage,vacuum motor ran great off car .

[beerczar1976]

Fixed it!  Found that the self-remember on the pillows were exerting to much pressure.  Second reason MIGHT have been than on ends of the cables there is a small bead...think of those that are on the end of a bicycle brake or shift cable.  One had slid in about 1/ 32" further than it should have been to the slotted retainer on the transmission link effectively shortening the cable by about 1/32" .

[Frank DuVal]

Was DOT brake fluid suggested by some vacuum wiper publication?  DOT 3 is hygroscopic, and air is always flowing through the wiper motor in operation, bringing moisture with it. DOT 3 in brake systems is somewhat sealed and still builds up white corrosion. Seems it will do the same in the wiper motor.