How to:Disassembly and cleaning of Air Wiper Motors on GMC's.

Gunfreak25

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Each paragraph corresponds with each picture from L to R

-Here is our candidate. Full of rock hard grease, leaky gaskets and plugged inlet and exhaust ports. They are very easy to fix!

-First remove the inlet hose barb and exhaust fitting

-Remove these 6 machine screws

-Gently pull the left valve cap and valve assembly out and lay it down like so

-The valve is spring loaded and has 2 detent positions. This is the up position.

-Press it down into place like this

-The thin metal rod has two hooks at the end that connect to the valve. Unhook the rod like so

-Picture showing the hooks and how they engage the pin on the valve

-Go ahead and remove the right cap and 6 machine screws too

-Back to the left side with the valve rod. Pretty nasty! I believe the old grease is vegetable based and STINKS like all get out.

Continued below....
 

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Gunfreak25

Active member
1,372
2
38
Location
Yuma, AZ
-Next remove the top plate and 2 tiny screws.

-Remove this screw

-Remove 2 screws and windshield mounting bracket. Note the orientation of all the flat and spring washers, I try to put them on in the same order they were removed

-Cracked rubber O ring, replace this

-Pull the manual control lever straight out

-Pull out the control lever gear

-Slide the piston assembly out either side.
 

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Gunfreak25

Active member
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Location
Yuma, AZ
Okay!!! Finally had a few min to post the pictures! I do not have time to cover reassembly right now. Just follow the pics in reverse order and it will go back together just fine.

Cleaning/Reassembly Tips

-The end cap's use paper gaskets. I just sealed them back on with a thin bead of RTV. The top cap that covers up the control gear also uses a paper gasket, again just use RTV.

-The piston cups are leather and removing them is not necessary, you'll just bugger the screws and there is nothing to be gained by taking them off. I soaked everything in mineral spirits for 48 hours followed by a tooth brushing.

-Apply a thin coating of wheel bearing grease to the cylinder bores. Apply a thin coating of wheel bearing grease to the leather cup's one end at at a time. Install the greased end in the bore, grease the gear teeth, slide in further, grease last cup and slide all the way back in.

-You can finish packing some extra grease into the bore through the top hole in the cylinder with a grease gun.

-Make sure the valve is very clean and the ports are clear. Apply a few drops of oil to the valve mechanism at all the hinge points.

-Make sure the hose barb is clear of debris as well as the exhaust port. A plugged exhaust port will not let the wiper operate at all. Mine were all clogged 100% solid and I had to burn out the debris with a wire pick and a blow torch.

-Lastly, replace the manual control shaft O rings on both ends. Common parts store O rings.

They are really hard to break and should last 50 more years if taken care of. If you accidentally bend the thin metal valve control shaft don't be afraid to bend it back to shape.

This should help anyone who was afraid of opening up a mystery can of potential springs and small parts. As you can see they are quite simple.
 
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