Vacuum Pump Test

CARBERAME · Post by **CARBERAME** » Mon Jul 01, 2019 3:03 am

I would like to know how can I test the Vacuum Pump as the pressure I get out of it going to the wiper motors is quite low. Any suggestion please?

Post by **wesk** » Mon Jul 01, 2019 8:46 am

Please list which model jeep your are asking about and if it is in original factory configuration or not. If you wish you can add a signature entry for all your posts by going to your profile and adding your preferred name to be addressed with and the make/model of MV's you own.

If it is an M38, M38A1 or M170 and it is in original factory configuration then this is your source of information. The pressure side of the vacuum pump is vented. It is the suction side of the vacuum pump that is the the side to be measured and it is measured with a vacuum gauge which is a measurement of less than 0.0 PSI and is displayed in an "Inches of Mercury" scale. In TM 9-8012 (Section IV Paragraph 79 [fig 22] page 80 and Section VIII Paragraph 127b page 151 "Data" lists parameters.) for the M38 and TM 9-8014 (Section IV Paragraph 103(3) page 99, Section V paragraph 107[ figure 39] and Section VIII Paragraph 133bpage 144 "Data" lists parameters.) for the M38A1/M170. These two manuals are available free on our "Downloads" page:
http://www.willysmjeeps.com/v2/modules. ... =Downloads
http://www.willysmjeeps.com/v2/modules. ... oad&cid=60

M38 manuals: http://www.willysmjeeps.com/v2/modules. ... oad&cid=62

M38A1/M170 manuals: http://www.willysmjeeps.com/v2/modules. ... oad&cid=63

CARBERAME · Post by **CARBERAME** » Tue Jul 02, 2019 4:09 am

Hi Wes

I do appreciate your information and comments regarding my post. The information given will be absolutely useful for me.

I own 3 M38, 1 M38A1, 1 Mutt and a Command Dodge WC56. My question regardin vacuum was for the M38 specificly.

Next week end I'll make all mesurements you suggest me and will let you know the results.

Thanks for your attention

Carlos

CARBERAME · Post by **CARBERAME** » Sun Jul 07, 2019 5:17 am

Wes

I,ve mesurad the vacuums in the M38 and the readings are:

In the exhaust manifold: 17/18
In the Out of Vacuum pump: 17
In the wiper motor: 14

And the wiper motor doesn't move

I checked these same mesures in an other M38 I own and they are almost the same and in this one the wipers work perfectly.

Could it be that the wiper motors are defective?

Thanks again

Post by **wesk** » Sun Jul 07, 2019 10:49 am

They require frequent attention if they are expected to perform adequately over many years. This includes cleaning and lubrication. Unfortunately the manufacturer did not make this an easy task by using rivets instead of easily removable fasteners. Sometimes if the wiper motor will operated easily by hand then the introduction of a lubricant to the vac source port and continued operation by hand may improve the operation of the motor without disassembly.

There is not a lot of publications out there for the rebuilding of these vacuum motors. However there are a few good links:

https://rebuildingtricowipers.com/
http://hudsonterraplane.com/SuperSix/Wiper/wiper.htm
https://www.hagerty.com/articles-videos ... our-wipers

CARBERAME · Post by **CARBERAME** » Mon Jul 08, 2019 4:12 am

Thanks Wes,

I wish I could be able to correspond to your information and help.

Your comments have been of great use and appreciate them

Thanks

carlos