 What is a safe vacuum value to test a MPS?, ...aka the value of looking at VW shows for teener stuff! |
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| 914rrr |
 Sep 7 2025, 07:00 PM
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#1
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Senior Member  Group: Members Posts: 1,976 Joined: 1-July 03 From: Knoxville, TN Member No.: 874 Region Association: South East States  |
While cruising the swap meet section at a VW Show yesterday, I picked up an in the box NOS 049 MPS. (IMG:style_emoticons/default/dancinnanner.gif)
I did the :suck tongue" test and it passed. I'd like to test it with a pressure / vacuum tester to ensure it holds vacuum. I definitely don't want to overdo it and damage it. What is a safe vacuum value to test an MPS?  |
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Replies(1 - 4)
| JeffBowlsby |
Sep 7 2025, 08:18 PM
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#2
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914 Wiring Harnesses & Beekeeper Group: Members Posts: 9,104 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None 
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18 in/Hg is used to calibrate.
Mouth suck test is no good, no where near enough pressure. Use a vacuum pump. |
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| 914rrr |
Sep 8 2025, 12:42 PM
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#3
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Senior Member Group: Members Posts: 1,976 Joined: 1-July 03 From: Knoxville, TN Member No.: 874 Region Association: South East States |
QUOTE(JeffBowlsby @ Sep 7 2025, 10:18 PM)  18 in/Hg is used to calibrate. Mouth suck test is no good, no where near enough pressure. Use a vacuum pump. Thanks Jeff!! |
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| 914rrr |
Oct 30 2025, 09:02 AM
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#4
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Senior Member Group: Members Posts: 1,976 Joined: 1-July 03 From: Knoxville, TN Member No.: 874 Region Association: South East States |
OK, it passed the vacuum text with flying colors.
What static electrical tests can be performed to check operational condition? |
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| Ron914 |
Oct 30 2025, 09:51 AM
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#5
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Member Group: Members Posts: 440 Joined: 19-April 22 From: Huntington Beach,Ca Member No.: 26,487 Region Association: Southern California
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QUOTE(914rrr @ Oct 30 2025, 10:02 AM) OK, it passed the vacuum text with flying colors. What static electrical tests can be performed to check operational condition? With a volt /ohm meter check the ohm readings for the primary and secondary coils then check each coil to case ground . The secondary coil should read around 350 ohms between pins 8 &10 and the primary coil should read 90 ohms between pins 7 &15 then check each to case ground there should be no continuity from case to either 7/15 or 8/10 |
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