Wiper motor problems

Hello everyone. New to the forum and to the MV world. Recently purchased a 1971 M35A2 and now going through it. The drivers side wiper works great but the passenger side doesn't work at all. I've verified that air pressure is present at the right side motor but never gauged it. The motor works ok on the bench using a blow off nozzle but not in the truck. Any tricks to all this or do I just need to replace that wiper motor?

Plastic or metal wiper motor?
They can be opened. Sometimes a swollen O-ring causes them to stick.
You can spray a little silicone lubricant into the air intake port and run the motor and see if that gets it going.

A long time ago I made a writeup when I fixed mine: https://www.steelsoldiers.com/showthread.php?56882-Plastic-air-wiper-motors-repair-how-to

Didn't know there was any kind but plastic? Anyways this one is antic. Thanks for the tip. I was tempted to open it but hesitated without knowing more. I did put a few drops of air tool oil in, though. Looks like I'll be opening it up. Thanks again.

Yup, air tool oil will make the O-rings swell and the motor locks up....done that.

Great! It was bad and I made it worse. Figures.....

Cattlerepairman, just read your How-To link. Excellent information. This shouldn't be hard at all to fix. Since I can hear air hissing on each manual stroke, I'm betting on a torn/cut o-ring. Thanks again for your help.

They are easy to fix. Don't give up.

Update: Turns out I didn't make it worse with the air tool oil. After taking the endcap off, I discovered it had been packed with what appeared to be wheel bearing grease; very old grease too. After full disassembly and cleaning, I found flat spots on both o-rings. Obviously, the grease was a quick fix for the bad o-rings. I put in new o-rings but used o-ring grease instead of silicone for lubrication. O-ring grease, applied very sparingly just to give the o-ring a light sheen, will not only lubricate the o-ring, it also helps protect it from contaminants and drying out. Anyways, the whole process took about 15 minutes and the motor works great. Although the driver's side functions well, I'll probably take it apart as well. Thanks again for the information. Very helpful!

If it ain't broke don't fix it

If it ain't broke don't fix it...yes, that's one way to approach this but not always the best for overall equipment reliability. I run a Facilites/Maintenance Dept. for a large contract manufacturer. My predecessor used the "if it ain't broke don't fix it" approach and instilled that philosophy in all of the maintenance techs. Equipment uptime at it's best was 60%. That's when he was promoted to "predecessor". When I came on board I changed the philosophy to the following: If you do not schedule time on your equipment for planned maintenance, your equipment will schedule it for you. PLANNED MAINTENANCE is ALWAYS less expensive than unplanned repairs. Uptime is now sustained at 95% and we've more than doubled our production output over the last 4 years. Don't get me wrong here and I don't mean to lecture anyone. There is a time and place for "if it ain't broke don't fix it". Just make sure you weigh all the variables and consequences before deciding which approach is best.

So, here's my thought process on the driver's side motor...
Yes, the driver's side wiper motor is working ok right now; however, assuming it was assembled with grease like the passenger side, if I don't service it, Murphy's Law states it will stop on me at night during a torrential downpour on some back country road where I can't get cell service and I'd forgotten to throw some extra tools and parts in the cab with me and my flashlight will stop working at that point too because I forgot to change the batteries and my wife will be right there snickering and saying "I told you so" right before she reminds me she has to pee and I haven't realized I pulled over and stopped in 2 feet of standing water because I couldn't see out the windshield cuz of the busted wiper motor but she's going to tell me just how stupid I am for stopping there right after she jumps down into said water (without a flashlight) to go pee in the bushes because I suggested she do that! And she'll use plenty of adjectives to go along with "stupid".

So in this case I'll play it safe and go with planned maintenance....

Hi Sgt C

See your from New Hampshire and new to SteelSoldiers welcome aboard, hope to meet you at events.

Agree with you on finding the issues before they become problem that leave you on the side of the road. Running the MVs of similar/common design, if one of them develops a problem is to check the other two.

Cheers Phil

My truck has a plastic POS that never worked, the case was split and air was leaking so I had to cap off the line to the pass wiper. Driver side works like new, and it's the metal TRICO one. I took the plastic one apart and that's what he's I found the crack. I've seen rebuild kits online for around $20 also, and wasn't that hard to take apart

I was fortunate to have the orings in stock in my shop. I did look them up in McMaster Carr just in case. $7 for a package of 100. I didn't even know there were metal motors until I saw the first reply to my post. Might upgrade at some point but I need to keep going through the truck getting everything up to par. Tackling front axle boots now. Never realized kitchen &bath white rtv was government issue...

Sgt C said:

I was fortunate to have the orings in stock in my shop. I did look them up in McMaster Carr just in case. $7 for a package of 100. I didn't even know there were metal motors until I saw the first reply to my post. Might upgrade at some point but I need to keep going through the truck getting everything up to par. Tackling front axle boots now. Never realized kitchen &bath white rtv was government issue...

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Supposedly there is an electric motor conversion kit, but personally I like keeping everything original as much as I can. I don't want the spin on filter conversion, I'm keeping the wipers air operated, never gonna Bob it, and never gonna use an other tire than 9x20 NDCCs

Agreed but might give in and go for 11X20's at some point.

Oof. 11x20s gonna be a bit harder to get that split ring on there. Tough enough by myself

I thought the 9.00 X 20's were getting scarce? I like the tread pattern on the Michelins.

Nooooo no way. A buddy of mine has 600 9x20s and I have a barter system with him, I fix his trucks, he gives me tires

So scarce for me...not so much for you.

Wrenchstench92 said:

Supposedly there is an electric motor conversion kit, but personally I like keeping everything original as much as I can. I don't want the spin on filter conversion, I'm keeping the wipers air operated, never gonna Bob it, and never gonna use an other tire than 9x20 NDCCs

Click to expand...

There is a factory electric wiper kit. All of the M44A3 model trucks had it and I have bought 3 or 4 M44A2 trucks directly from the govt. that had the M44A3 electric wiper set up. It works great.

Wrenchstench92 said:

Oof. 11x20s gonna be a bit harder to get that split ring on there. Tough enough by myself

Click to expand...

They aren't terrible.



There is another aspect to the plastic wipers.

https://www.steelsoldiers.com/showthread.php?17273-Air-powered-wiper-Questions&highlight=