85-91 Wiper Motor Rebuild

[Doppleganger]

fwiw.....I located the terminals used in the chassis side harness for these - dont think that part is ever included in any 'new' harness kits. 35-40 yr old wiring can be an issue as well.

 

[Doppleganger]

A couple of troubleshooting diagrams I came across also.

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[scrap--metal]

That wiper motor is a work of art now! Thank you @Doppleganger for the detailed write up and the excellent pictures. I will certainly reference this when I deal with the wiper motor on my K20.

 

[SirRobyn0]

@Doppleganger Chris, I've reread your guide now that I can think clearly. There are a lot of steps and small parts, but it's very clear and understandable to me, kind of like rebuilding a carburetor, lots of small parts and need to be done in a certain way. I really only have a few questions relating to the paint / plating ect.

So at the shop I have access to a sandblaster, so I could clean up a housing no problem and then what, do you think a guy could get away with priming and painting inside and out forgoing plating of any kind? And if so could you recommend a paint or primer that would hold up well.

And then lets suppose someone is doing this at home, no blast cabinet, do you think a guy could get away with cleaning up the housing in a muriatic acid bath? (or do you think that would destroy the housing?) Or a commercial paint stripper?

Thanks.

 

[Doppleganger]

@SirRobyn0

Honestly....this was so overkill (which is why I picked the motor in the worst condition....figured if that one could be redeemed, then what would a nicer one be like?). The other 2 motors had a fraction of the corrosion - in fact the motor from my own (an Oregon truck) - the inside is still 90% shiney - only corrosion was in a few places around the perimeter holes where moisture easily got in. Even the terminals were still shiney copper. But unless its a basket case, I think most of the time one could get away with just cleaning and maybe using a scotch brite to remove the built up crud.

I had asked about powder coating the housing and was told by the powder coater that the finish would pop (tiny blisters) on fresh plating. I have also had parts that needed plated but couldn't be because of materials involved or attached to the part....on those (per the plater) I used a 65% zinc paint, and that worked better than expected. So there's that. IMO, not crazy about painting inside this housing - seems to me the possibility of peeling or in some cases, the clearances are so small, it would affect the fit. Thats just my take on it.

I have thought about doing one of these like you say with no access to plating or blasting. No plating or even new parts - just see what it would take to clean it, lube it and send it on its way, like most (even the place that wants $350) would probably do.

And then another step which I may try on the next one, is to add a film of Permatex to seal the 2 halves as thats the area where water is obviously coming in.

Biggest issue I think anyone is going to have doing one of these is the 40 yr old plastic parts inside of which NONE are available and any damage makes them unusable. Like I've said, 40yr old parts in a truck that had a 12 month warranty when new. That plastic brush holder is the biggest issue. The rubber isolator on the shaft.....not available, but Benz's have something very similar that might fit....I just didn't feel like dropping $20 + S/H to see if it would.

I'm going to collect all the ones I can find - for spares if anything. When I get things plated, its like powder coating: can get 5 plated for what 3 would be quoted. I'll have a pile of these housings all plated at once so would have spares if need be. Same way with the brushes, etc.

 

[Snoots]

@Doppleganger for the WIN!!!
Awesome thread and work!

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[HotRodPC]

Fantastic addition to the forum @Doppleganger . Thx so much !!! I'll be one that needs to visit this thread sooner or later. My wipers barely move at first. Left on long enough they will eventually move a bit better. Figured a good cleaning and lubing of the rods and then this info right here they'll be working like brand new again someday.

 

[SirRobyn0]

Since Hotrod mentioned "rods" I assumed he meant the wiper linkage and I thought maybe it would be worthwhile to link the wiper linkage rebuild thread to this thread since some folks might need both. I'll link this thread in that one as well.

Wiper linkage rebuild thread: https://www.gmsquarebody.com/threads/rebuilding-wiper-linkage-how-to.35509/

 

[HotRodPC]

Since Hotrod mentioned "rods" I assumed he meant the wiper linkage and I thought maybe it would be worthwhile to link the wiper linkage rebuild thread to this thread since some folks might need both. I'll link this thread in that one as well.

Wiper linkage rebuild thread: https://www.gmsquarebody.com/threads/rebuilding-wiper-linkage-how-to.35509/

Yep, the linkage, rods, arms, stiffies, pushers and pullers or any other name we can think of. Great info between the 2 of these.

So onto another question, one of you two may very well know the answer to... So this motor rebuild is for 85-91 models. So if someone had an older square, is this 85-91 motor backwards compatible to where it could be swapped into older models? Maybe just back to 1981 models after the cowel and hood set up change? Or perhaps all that way back to 1973?

 

[bucket]

Yep, the linkage, rods, arms, stiffies, pushers and pullers or any other name we can think of. Great info between the 2 of these.

So onto another question, one of you two may very well know the answer to... So this motor rebuild is for 85-91 models. So if someone had an older square, is this 85-91 motor backwards compatible to where it could be swapped into older models? Maybe just back to 1981 models after the cowel and hood set up change? Or perhaps all that way back to 1973?

It backwards swaps to '78. The big difference is there is no washer pump built in, so a remote mount pump is needed. The existing two wires that power the washer pump portion can be used to power the remote pump.

Besides the lack of a washer pump, the internals may be the same? I've never compared them side by side.

 

[Doppleganger]

Yep, the linkage, rods, arms, stiffies, pushers and pullers or any other name we can think of. Great info between the 2 of these.

So onto another question, one of you two may very well know the answer to... So this motor rebuild is for 85-91 models. So if someone had an older square, is this 85-91 motor backwards compatible to where it could be swapped into older models? Maybe just back to 1981 models after the cowel and hood set up change? Or perhaps all that way back to 1973?

Very glad (and relieved) you fellas like it. That was the hope anyways.

I'm picking up a 79 wiper motor tomorrow and intend on dissecting it shortly. A couple pics didn't come out in the 85-91 wiper motor overhaul, so when I do the next one (also shortly) I'll add them in. I guess one step is to find the years of different motors and bag one of each style - open it up and see whats different. Cant see having build thread of each being a bad thing.

I also found the terminals that go to the motors, so as to make new pigtails (from the motor to to the bulk connector) if those are ever to be replaced.

fwiw.....if anyone gets overwhelmed, I'll swap you one thats done for your old one and a few $ (shipping, parts, required 12 pk). I'd make little-nothing on it.....just commandeered several motors for parts and dont need that many around. AND...nothing is available parts wise, so I'll have plenty of tested-good parking switches, brushes, and the harnesses eventually if you need also. Maybe a new-purtee housing? lol

 

[SirRobyn0]

I agree I think the biggest difference is the mechanical washer pump, but I think the park switch is different to, but I do not know that for sure. Certainly a guy could take Chris's guide and adapt it to any of the other GM windshield wiper motors. It might look a little different inside, but I think I guy could still adapt this guide to it. I'm planning on doing just that with me 77 Cadillac one of these days. It's got terribly slow, but functional wipers.

 

[SirRobyn0]

Yep, the linkage, rods, arms, stiffies, pushers and pullers or any other name we can think of. Great info between the 2 of these.

It's a a little funny and also ridiculous how many different names the linkage has. Another term I've heard for the wiper linkage more and more is regulator. Like window regulator, wiper regulator. And what about wiper transmission? I've heard guys call the gear drive part of the motor "wiper transmission" and also the linkage "transmission" IDK it's like camper shell, topper, canopy.

 

[SirRobyn0]

@Doppleganger If you want to do my 77 Cadillac wiper motor, I'll take it off and send it to you. On the outside it looks just like the one on my square with the mechanical washer pump. I'd make sure there is at least beer money in it for you. If I didn't drive the square so much I'd send you the motor off of it. It's a three year old WIA new unit. We have installed a few of those at the shop and they have been great, but given that they are new builds I'm curious what the differences are inside vs the original GM units.

 

[HotRodPC]

It's a a little funny and also ridiculous how many different names the linkage has. Another term I've heard for the wiper linkage more and more is regulator. Like window regulator, wiper regulator. And what about wiper transmission? I've heard guys call the gear drive part of the motor "wiper transmission" and also the linkage "transmission" IDK it's like camper shell, topper, canopy.

Or a front clip, doghouse, nose clip...