The vacuum motor in this photo is mounted at the top of a ventilating windshield which swings open (15K JPEG). On the more common non-ventilating windshield, the wipers are mounted at the bottom (70K JPEG.)
The vacuum hose (15K JPEG) connects the motor to a vacuum source under the hood.
One owner who had a problem finding a vacuum source to power the wipers posted this: "I recently purchased a '53 CJ3B and am trying to get the wipers working. The Jeep has a new fuel pump and I can't find a vacuum source on it. The carb doesn't appear to have one either. Other than 'Get a real fuel pump, Stupid!', is there another place to find a vacuum source?"
Ingvar replied: "Mine has a vacuum nipple in the head, directly below the carburetor on the passenger side. I don't know if it produces enough vacuum but I do know that I have a plug there now and the engine is very unhappy if I pull it off. Maybe yours is plugged as well and you don't recognize it as a vacuum source?"
Bart McNeil elaborated: "The 3B uses a double action fuel pump. This is a combination fuel pump and vacuum pump. It is easily identified by the two open pipes attached to the base of the pump. You apparently have a single action pump which was used on CJ-2A's and did not have the fuel/vacuum pump comination. Ingvar's answer is correct up to a point, and you can operate your wiper motor from the intake manifold vacuum. However the vacuum in the intake manifold varies so much that windhield wiper action will be sporadic. The double action fuel pump was designed to alleviate this problem. When the vacuum is too low to operate the wipers at proper speed a valve opens and the vacuum motor in the fuel pump becomes effective assisting in creating proper vacuum to operate wipers consistently. You can certainly run your wipers from the intake manifold vacuum as Ingvar suggests. Many cars (like the CJ-2A) did just that. But for consistant and better performance the double action fuel pump is important."
Jim Sammons suggested: "There are belt-driven vacuum pumps made for diesel engines. My Ford F-250 7.3 liter diesel has such a pump to supply vacuum to the brake booster. You may not want to do this as it will require fabrication of brackets -- it's just a thought."
Tim Salkeld confirmed: "I posted a similar note on this board last year -- the response was the same. The 3B has a double action pump to supply vacuum for the wipers. You can also use manifold vacume as I am and keep the older model pump. The downside to this, apart from not being correct for restoration, is that the faster you go the less vacuum your engine produces and the slower the wipers work. Push in the clutch and let the engine slow down, then speed back up, and you have an intermittent wiper that would only become standard equipment on SUV's much later.... It will work until you can find the double acting pump."
See Crankcase Ventilation System Tech Tips, and Rebuilding an F-head Engine, Page 8: Vacuum Lines for details on vacuum and fuel line routing.
Roger Bensgård: "I have purchased NOS arms and Trico blades from Peter DeBella in New York (516) 874-8660. They are for ther MB/GPW but I think you could use them for CJ3A/3B (perfect fit for my CJ2A)."
Reed Cary: "The blades I purchased from JC Whitney (admittedly, a couple of years ago) were garbage. I ended up making my own by buying a heavy-duty adjustable truck arm and blade from NAPA and cutting the blade - I think 18" - to make two smaller. The only problem with this, I found, was that the spring was too heavy and stalled the wiper motor. I then tried progressively weaker springs until I found the right match. (It is this spring pressure which cocks the socket on the arm, and thus holds it to the flutted nut on the motor shaft.) But you might want to keep looking for a source to avoid the trouble I went through."
Tony Morreale: "Turner 4WD (1-800-THE-JEEP) has the arms and blades. I bought mine over 2 years ago and they are still going strong. I forget the price, but the quality is as the originals were."
Bart McNeil: "Beachwood Canvas has them both. Arm: $13.20 each. Wiper blade: $6.00 each. Plus shipping."
Scott Blystone notes that: "Military vacuum wiper motors will not fit a civilian Jeep. The mounting holes for the M38A1 are 4.5" apart, versus 3.5" for CJ-2A, CJ-3A and B."
Hollis Wooldridge recommends re-lubricating vacuum motors before doing any more extensive rebuilding: "I pulled mine off and took the back plate loose without removing the little lever. Soak the whole thing in WD40 and then some 30-weight oil. Make sure the oscillator is moving side to side and then apply some vacuum - you have a good chance with this simple treatment. Neither of mine were working before but both work quite well now; usually it is a lack of lubrication."
Further comments are welcome. -- Derek Redmond
Some sources for wiper motor parts and repair:
Jon Paulsen said not to worry: "I put a connector on the wiring to it, and just pull it off in the summer, since I run topless all summer. If you go fast enough in the rain, it all goes over the top! Highly recommended form of outdoor recreation!"
Ed Wilson described his solution: "I've used the 6-volt electric replacement wiper for several years and it also had the too-long shaft. I had a friend machine an aluminum spacer block to install on the inside between the the winshield frame and the motor proper. It works well. The problem I've encountered is replacement blades for the thing."
Dave Specht suggested a nut might serve the same purpose: "I just got one of those wipers today and thought I could put another nut on the inside to move it back. I went to the hardware store and the nut is apparently 9MM. I didn't find one, but will try tomorrow."
Tony Morreale gave instructions for shortening the shaft: "I had the same problem with my wiper motor, and a hack saw fixed everything. Just install the wiper motor in your windshield frame. Mark the outer threaded shaft a little outside the retaining nut. Remove the motor, put the nut back on the shaft. Take the hack saw and carefully cut the outer shaft. Do not cut the inner shaft - the piece you attach the arm to. Go slowly and rotate the unit as needed to cut around the entire piece. Once this is done you should have the inner shaft, plus the shortened outer shaft. Measure the depth of the receiving end of the wiper blade arm. Cut the inner shaft to length. Remove the nut from the threaded shaft -- this will ensure that the threads are OK. Remount the unit and you should be able to fold down the windshield, provided your hood blocks are the right size. Remember: measure twice, since there is no turning back once you've cut the threaded sleeve. I did my motor from Surplus City over a year ago and it works great."
Joel Kamunen mentioned an alternative product: "If you have the J.C. Whitney style of wiper set up they do need to be cut down so you can fold the windshield down. A small Dremel tool with a cutoff blade works nicely. The other option is to use a better windshield wiper motor set up. There is a wiper available from Around The World Parts (1-888-884-3512). It costs about $90.00 but won't burn out like the cheaper units. I believe it has the correct shaft length also. I am going to install the better unit on the drivers side and use my old one on the passengers side."
Jim Sammons added: "You can get marine electric wiper motors from Perko with just about any length and diameter shaft you want. The marine units are usually very heavy duty and will work forever. Plus they're built for a salt water environment so it won't hurt them if they get rained on when the top is off."
See also Manual Wiper Conversion and Repair for tips on the passenger-side wiper.
Return to Tech Tips on The CJ3B Page.
CJ3B Home | Site Map | History | Photos | Tech | Links | Bulletin Board