Testing a 68 vacuum system-just sharing !
Thread Starter
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Testing a 68 vacuum system-just sharing !
Some have ask where I get the patience for working on the vacuum systems so I thought I would share some of what makes it a little easier and less frustrating for me. I disconnect the vacuum at the manifold and put in my T with the vacuum gauge , the little clear line runs outside the garage to a vacuum pump. Can you imagine how hot my garage would get if this BB was running. 
In this initial test you can see I have a few hoses pinched off , I'm testing the tank,lines going to the tank ,the small control line going to the wiper relay, small lines going inside to the HL switch and the pulldowns. As you can see its holding around 24" vacuum , just where I preset my vac pump so I'm pretty satisfied with those parts of the system. After more testing I found that the HL relay and the wiper relay were both leaking in the large hose portion of the relay. Owner said that both relays are new. 
In this initial test you can see I have a few hoses pinched off , I'm testing the tank,lines going to the tank ,the small control line going to the wiper relay, small lines going inside to the HL switch and the pulldowns. As you can see its holding around 24" vacuum , just where I preset my vac pump so I'm pretty satisfied with those parts of the system. After more testing I found that the HL relay and the wiper relay were both leaking in the large hose portion of the relay. Owner said that both relays are new.
Team Owner
Joined: Jul 2008
Posts: 23,419
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
Roger:
I need to do some work on my vacuum system, but the auto parts store and Sears both give me blank looks when I ask for a vacuum pump. Is there a brand or vendor you recommend for one?
PK
I need to do some work on my vacuum system, but the auto parts store and Sears both give me blank looks when I ask for a vacuum pump. Is there a brand or vendor you recommend for one?
PK
Drifting
Joined: Jul 2006
Posts: 1,259
Likes: 154
From: Deplorableville Nebraska
Here's the vacuum pump I use. Found it on that auction site. Pulls down to 15 lbs, which is about what my L46 pulls at idle. I believe it is surplus medical or dental equipment. Not bad for $40.00. I still use my Mityvac to test each individual component.
Thread Starter
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Mine is a James Corp. and it was pretty pricey but its also used for home AC , it pulls down and shows 30 on the gauge (impossible I know). Dang motor dims the lights when you start it.
Team Owner
Joined: Jul 2008
Posts: 23,419
Likes: 22
From: In limbo
St. Jude Donor '13-'15, '17 thru '22
Roger's looks like overkill for what I will be working on, but I will check Harbor Freight online.
Thanks guys!
Team Owner
Joined: Jul 2008
Posts: 23,419
Likes: 22
From: In limbo
St. Jude Donor '13-'15, '17 thru '22
Just checked Harbor Freight, this is the smallest they apparently offer:
http://www.harborfreight.com/25-cfm-...ump-98076.html
I like DaveJ's better, but it apparently isn't called a "Mityvac". Dave, do you have a make and model on that?
Thanks,
PK
http://www.harborfreight.com/25-cfm-...ump-98076.html
I like DaveJ's better, but it apparently isn't called a "Mityvac". Dave, do you have a make and model on that?
Thanks,
PK
Thread Starter
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
MityVac is the hand model for individual component checking.
http://www.harborfreight.com/mityvac...ump-39522.html
http://www.harborfreight.com/mityvac...ump-39522.html
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
There is a lot of difference between measuring vacuum in PSI (pounds per square inch) or in inches of Mercury (in. Hg). Most auto resources measure vacuum in inches of Mercury. In quantitative terms, the number of inches of Mercury is about twice as much as the same measurement given in PSI. [2.036 in. Hg is equal to 1 PSI]
The reason I even bring this up is that some of the components in your C3 vacuum system could be damaged if you draw much more than 12-13 psi from them [equivalent to 24-26 in. Hg.].
The reason I even bring this up is that some of the components in your C3 vacuum system could be damaged if you draw much more than 12-13 psi from them [equivalent to 24-26 in. Hg.].
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Drifting
Joined: Jul 2006
Posts: 1,259
Likes: 154
From: Deplorableville Nebraska
The maker of mine is Medical Industries of America, and the model is #601. The seller listed it as a vacuum tester for Corvettes, but I guess it's really called a medical aspirator. If your interested in picking one up, search under Business & Industrial > Healthcare > Aspitator. I did a quick search and came up with these examples..........
http://cgi.ebay.com/Schuco-Model-132...item1c13847452
http://cgi.ebay.com/GEN-MED-GENERAL-...item27b2a4cea0
I only use this to check the overall system, or to check a series of components. The Mityvac hand pump works great for individual components.
Melting Slicks
Joined: Apr 2010
Posts: 2,795
Likes: 1,196
From: Canberra Australia
2025 C3 of the Year Finalist - Modified
Have tracked down a vacuum pump similar to the Harbor Freight one listed above in Australia.
Harbor Freight model mentioned above.....
http://www.harborfreight.com/25-cfm-...ump-98076.html
Model I can find in Australia....
http://cgi.ebay.com.au/ws/eBayISAPI....K%3AMEWAX%3AIT
Before I go ahead and buy it can someone please advise if 2CFM is enough or should I look for a more powerful one.
The importer does not have any more specs (HG PSI etc)
Harbor Freight model mentioned above.....
http://www.harborfreight.com/25-cfm-...ump-98076.html
Model I can find in Australia....
http://cgi.ebay.com.au/ws/eBayISAPI....K%3AMEWAX%3AIT
Before I go ahead and buy it can someone please advise if 2CFM is enough or should I look for a more powerful one.
The importer does not have any more specs (HG PSI etc)
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Have tracked down a vacuum pump similar to the Harbor Freight one listed above in Australia.
Harbor Freight model mentioned above.....
http://www.harborfreight.com/25-cfm-...ump-98076.html
Model I can find in Australia....
http://cgi.ebay.com.au/ws/eBayISAPI....K%3AMEWAX%3AIT
Before I go ahead and buy it can someone please advise if 2CFM is enough or should I look for a more powerful one.
The importer does not have any more specs (HG PSI etc)
Harbor Freight model mentioned above.....
http://www.harborfreight.com/25-cfm-...ump-98076.html
Model I can find in Australia....
http://cgi.ebay.com.au/ws/eBayISAPI....K%3AMEWAX%3AIT
Before I go ahead and buy it can someone please advise if 2CFM is enough or should I look for a more powerful one.
The importer does not have any more specs (HG PSI etc)
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
I've heard Harbor Freight has some that are reasonable. You don't need anymore than what Dave has. You can also take the compressor out of an old fridge I understand and use it. You can also use another car with a long hose from the engine.
Mine is a James Corp. and it was pretty pricey but its also used for home AC , it pulls down and shows 30 on the gauge (impossible I know). Dang motor dims the lights when you start it.
Mine is a James Corp. and it was pretty pricey but its also used for home AC , it pulls down and shows 30 on the gauge (impossible I know). Dang motor dims the lights when you start it.
Doing the amount of vacuum work you do, a refrig or a/c compressor might be a good idea. Next time you're down south get a decent size compressor from a split system, lots for free down here.
Le Mans Master
Joined: Nov 2001
Posts: 8,807
Likes: 1,947
From: LONG ISLAND
2025 C3 ('68-'73) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
i sold these years ago for a company called JOHN BUNN they also sell things like nebulizers...............now there is a more relevent use for one in my life !!!
http://www.grahamfield.com/Medical_P...g=0&p=2215&v=1
Last edited by 427SIXPACK; Sep 14, 2010 at 11:33 AM.
