The Ford Barn

mcgarrett · 08-31-2025, 09:47 PM

I picked up a couple of 1940 Ford wiper motors recently that seem to be in really nice shape. The motor action on both of them is very smooth and the suction feels really strong. After I confirm they are in good working order I plan to install one of them - the one in the car is DOA.

I've read a few posts here on the Barn that advise to introduce some Marvel Mystery Oil into the vacuum port and work it into the flapper valve mechanism. Is that still the preferred maintenance method or is there something better to go with? Replacing the wiper motor on a '40 Ford is a real pain, so I want to make sure to do it right the first time!

Newc · 09-01-2025, 10:57 AM

Clean Sweep co' in Redmond, Or MM mystery oil has an acid, use a mild mineral oil in air intake. Newc

JayChicago · 09-01-2025, 11:27 AM

About nine years ago I used a few drops of "3-in-1" brand light oil. Still working fine. I wouldn't over think this. Probably any light oil will work.

JayChicago · 09-01-2025, 11:34 AM

BTW, I thought the 1940 wiper motor was an easy R & R. But I don't have a radio. Totally different story if you need to remove a radio to even see the wiper motor.

mcgarrett · 09-01-2025, 02:13 PM

Quote:

Originally Posted by JayChicago

BTW, I thought the 1940 wiper motor was an easy R & R. But I don't have a radio. Totally different story if you need to remove a radio to even see the wiper motor.

Yep, I have a radio. Removing the front seat makes the job easier.

mfirth · 09-01-2025, 03:25 PM

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I used a few drops of ATF, works for me.

08-31-2025, 09:47 PM	#1
mcgarrett Senior Member Join Date: Dec 2013 Location: Corsicana, Texas Posts: 1,551	'40 Ford vacuum wiper motor maintenance I picked up a couple of 1940 Ford wiper motors recently that seem to be in really nice shape. The motor action on both of them is very smooth and the suction feels really strong. After I confirm they are in good working order I plan to install one of them - the one in the car is DOA. I've read a few posts here on the Barn that advise to introduce some Marvel Mystery Oil into the vacuum port and work it into the flapper valve mechanism. Is that still the preferred maintenance method or is there something better to go with? Replacing the wiper motor on a '40 Ford is a real pain, so I want to make sure to do it right the first time!

09-01-2025, 10:57 AM	#2
Newc Senior Member Join Date: May 2010 Posts: 3,052	Re: '40 Ford vacuum wiper motor maintenance Clean Sweep co' in Redmond, Or MM mystery oil has an acid, use a mild mineral oil in air intake. Newc

09-01-2025, 11:27 AM	#3
JayChicago Senior Member Join Date: Jan 2019 Location: Chicago Posts: 1,028	Re: '40 Ford vacuum wiper motor maintenance About nine years ago I used a few drops of "3-in-1" brand light oil. Still working fine. I wouldn't over think this. Probably any light oil will work.

09-01-2025, 11:34 AM	#4
JayChicago Senior Member Join Date: Jan 2019 Location: Chicago Posts: 1,028	Re: '40 Ford vacuum wiper motor maintenance BTW, I thought the 1940 wiper motor was an easy R & R. But I don't have a radio. Totally different story if you need to remove a radio to even see the wiper motor.

09-01-2025, 03:25 PM	#6
mfirth Senior Member Join Date: Aug 2017 Location: ohio Posts: 1,165	Re: '40 Ford vacuum wiper motor maintenance Sponsored Links (Register now to hide all advertisements) I used a few drops of ATF, works for me.