vacuum test for c3 corvette
Thread Starter
Instructor
Joined: Nov 2015
Posts: 120
Likes: 15
vacuum test for c3 corvette
Hi Guys, I'm looking for something to help me in fix the C3 vacuum system when I can't test it with the engine running, like in these cold winter nights.
I've searched for a vacuum pump and found this air operated pump:
http://www.ebay.it/itm/3S-POMPA-del-...item210e7b7ba7
I wonder if I can use something like this or if an eletrical and more powerful one could be a better choise.
Thanks as usual!
I've searched for a vacuum pump and found this air operated pump:
http://www.ebay.it/itm/3S-POMPA-del-...item210e7b7ba7
I wonder if I can use something like this or if an eletrical and more powerful one could be a better choise.
Thanks as usual!
Race Director
Joined: May 2006
Posts: 18,694
Likes: 2,572
the american version I believe is below and it is intended to evacuate AC systems therefore it may be too much vacuum?
http://www.tooltopia.com/robinair-34...FY5LDQodJxEEAA
http://www.tooltopia.com/robinair-34...FY5LDQodJxEEAA
Thread Starter
Instructor
Joined: Nov 2015
Posts: 120
Likes: 15
Sorry, I can't open your link... anyway that thing could afford 4.2 CFM @ 90 PSI with 12,5 bar of maximum applied pressure with a compressor, but honestly I have no idea of how much vacuum our Vette needs, so every advice is really appreciated
Last edited by Proton_ita; Dec 12, 2016 at 04:08 PM.
Team Owner
Joined: Sep 2006
Posts: 31,211
Likes: 4,300
From: Westminster Maryland
Hi P_i,
The pump in your link indicates it creates about 4.2 cfm of vacuum at 90 psi.
I'd think that will operate the headlight doors and wiper door, but not at their normal speed.
I believe the typical engine vacuum is about 12-14 cfm?
Regards,
Alan
The pump in your link indicates it creates about 4.2 cfm of vacuum at 90 psi.
I'd think that will operate the headlight doors and wiper door, but not at their normal speed.
I believe the typical engine vacuum is about 12-14 cfm?
Regards,
Alan
Last edited by Alan 71; Dec 12, 2016 at 04:09 PM.
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
Drifting
Joined: Jul 2006
Posts: 1,259
Likes: 154
From: Deplorableville Nebraska
This is what I use, surplus medical aspirator. Industry standard model 905CA18, cfm around 1.3 @ 0 hg, .64 @ 10 hg. Will not blow seals etc @ higher hg, unlike the a/c units. Remember, you should be testing for individual component leaks, not actuating the whole system & chasing them. (remove the spit jar!)
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
Watch out with electrically powered vacuum pumps! They can produce far deeper vacuum than the engine and damage diaphragms, seals, housings, etc.
I'm not sure where you live but surely any country has something similar to the hand operated Mityvac. Even if you have one of the middle C3s with the huge vacuum tank/structural member at the front you can use that simple hand pump to test every component in the system without any chance of damage.
Yes, it can take a ridiculous number of hand pumps to bring a large tank down to the vacuum required for operation but by plugging all connections save one connected to engine vacuum with a tee off to the Mityvac (to use only as a vacuum gauge) you can very determine if the tank has a leak.
I'm not sure where you live but surely any country has something similar to the hand operated Mityvac. Even if you have one of the middle C3s with the huge vacuum tank/structural member at the front you can use that simple hand pump to test every component in the system without any chance of damage.
Yes, it can take a ridiculous number of hand pumps to bring a large tank down to the vacuum required for operation but by plugging all connections save one connected to engine vacuum with a tee off to the Mityvac (to use only as a vacuum gauge) you can very determine if the tank has a leak.
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Thread Starter
Instructor
Joined: Nov 2015
Posts: 120
Likes: 15
Hi, thanks for your advice. I have a '68 and I suspect that my problem is a little more tricky than a simple vacuum leak. I'll try to be the more precise I can:
When I purchased the car:
1- the wiper door actuator was broken and the door had to be manually opened in order to activate the wipers
2- the wiper door actuator line was disconnected from the vacuum reserve tank, and the headlight line was connected directly to the tank
3- With this configuration, the headlights worked properly despite they were a bit slow in open/close (maybe there's a small leak somewhere but I do not think that it could cause the main issue).
What I have already done:
1- I've replaced the wiper actuator with a new one and repaired the wiper door mechanics
2- I've tried to restore the original vacuum line with the proper tube line splitter, in order to connect both the headlight and wiper door lines to the reserve tank
My current issue:
With this configuration, the wiper door still not operate and the headlights open but refuses to close (I've checked the position of the override switches)
When I purchased the car:
1- the wiper door actuator was broken and the door had to be manually opened in order to activate the wipers
2- the wiper door actuator line was disconnected from the vacuum reserve tank, and the headlight line was connected directly to the tank
3- With this configuration, the headlights worked properly despite they were a bit slow in open/close (maybe there's a small leak somewhere but I do not think that it could cause the main issue).
What I have already done:
1- I've replaced the wiper actuator with a new one and repaired the wiper door mechanics
2- I've tried to restore the original vacuum line with the proper tube line splitter, in order to connect both the headlight and wiper door lines to the reserve tank
My current issue:
With this configuration, the wiper door still not operate and the headlights open but refuses to close (I've checked the position of the override switches)
Last edited by Proton_ita; Dec 12, 2016 at 07:04 PM.
Drifting
Joined: Jul 2006
Posts: 1,259
Likes: 154
From: Deplorableville Nebraska
I didn't see any mention of the relays. If your relays are leaking, you will continue to have problems. Have you checked them? In stock configuration, there is one shared with the two headlight actuators located between the headlight doors, and the relay for the wiper door is located rearward on the passenger side inner fender. For a test, if you were to apply vacuum to the large middle port and blocked the lower port, there should be no vacuum loss.
Advanced
Joined: Apr 2012
Posts: 61
Likes: 4
From: Discovery Bay CA
I bought this to change my boat oil...
Mityvac 7400 7.3 Liter Fluid Evacuator
then figured if it creates vacuum to pull the oil out of the boat motor it could be used to test the vacuum system on my 71. It has enough vacuum to operate the system. I added a rubber vac hose to the hard plastic lines( supplied with the pump) then hooked it to the Vette's system with a gauge I had. I got it at Amazon it was about $70.00
Mityvac 7400 7.3 Liter Fluid Evacuator
then figured if it creates vacuum to pull the oil out of the boat motor it could be used to test the vacuum system on my 71. It has enough vacuum to operate the system. I added a rubber vac hose to the hard plastic lines( supplied with the pump) then hooked it to the Vette's system with a gauge I had. I got it at Amazon it was about $70.00
Safety Car
Joined: Nov 2008
Posts: 3,717
Likes: 551
From: Seattle Washington
I have used a Refrigeration Vacuum Pump and it has the advantage of being used for more than one purpose ! Headlight System, Brakes and yes the AC. They are a pretty expensive, a used one that works is probably all You need. However You probably already have a free one sitting in the driveway. Just run a hose from the Car that's sitting out in the weather into your garage and You can test Your Headlight system. And with out the Engine running You can actually hear the Leaks....
Racer
Joined: Sep 2015
Posts: 250
Likes: 29
While i realize it's more expensive, I just ordered one for mine from Jegs. Its says it will increase vacuum to 18-22hg and has a built in switch. That along with a built in vacuum switch allows a safe range to be maintained. I also ordered an auxiliary vacuum tank which should allow even less cycling.
A fellow C3 owner who built a big cam engine like mine installed this same setup in his and commented about how much better his brakes and headlights worked. What he didnt figure on though was how much better his a/c controls worked !
http://www.jegs.com/webapp/wcs/store...rsistYmm=false
http://www.jegs.com/webapp/wcs/store...rsistYmm=false
A fellow C3 owner who built a big cam engine like mine installed this same setup in his and commented about how much better his brakes and headlights worked. What he didnt figure on though was how much better his a/c controls worked !
http://www.jegs.com/webapp/wcs/store...rsistYmm=false
http://www.jegs.com/webapp/wcs/store...rsistYmm=false
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Hi Guys, I'm looking for something to help me in fix the C3 vacuum system when I can't test it with the engine running, like in these cold winter nights.
I've searched for a vacuum pump and found this air operated pump:
http://www.ebay.it/itm/3S-POMPA-del-...item210e7b7ba7
I wonder if I can use something like this or if an eletrical and more powerful one could be a better choise.
Thanks as usual!
I've searched for a vacuum pump and found this air operated pump:
http://www.ebay.it/itm/3S-POMPA-del-...item210e7b7ba7
I wonder if I can use something like this or if an eletrical and more powerful one could be a better choise.
Thanks as usual!
The CFM@90 is the requirement for your compressor. It takes compressed air and runs it through a venturi creating a vacuum.
It can pull about 14" of HG vacuum, more or less depending on the capacity of your compressor. I makes a lot of air noise. You won't be able to hear vacuum leaks with it.
Last edited by REELAV8R; Dec 13, 2016 at 12:32 PM.
Melting Slicks
Joined: May 2011
Posts: 2,753
Likes: 119
From: Springfield Missouri
Willcox has a video on how to repair the wiper door area. Look at it first before ordering a lot of tools etc. on the head lights, check the hose connections, sometimes cutting off a half inch of hose will tighten it up enough to help hold vacuum, if not then Willcox has another video on how to check out the headlight vacuum. New hoses don't cost much.
Last edited by lvmyvt76; Dec 13, 2016 at 02:34 PM.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
This is what I use, surplus medical aspirator. Industry standard model 905CA18, cfm around 1.3 @ 0 hg, .64 @ 10 hg. Will not blow seals etc @ higher hg, unlike the a/c units. Remember, you should be testing for individual component leaks, not actuating the whole system & chasing them. (remove the spit jar!)
About 10 Years ago I snagged a dental vacuum pump on eBay for right at 100 bucks.. it's a 24 volt system but I a good power supply to power it up. We mounted both on a cart and just wheel them up to the cars. It's the only way to fly..
Ernie
Last edited by Willcox Corvette; Dec 13, 2016 at 08:55 PM.
Pro
Joined: Feb 2008
Posts: 556
Likes: 13
From: C3 Forum, Colorado
How about buying 30 feet or so of vacuum hose and connect one end to a vacuum port of a running vehicle outside of the garage with the garage door closed and connect the other end to your Corvette vacuum system?
I don't know the current cost of vacuum hose but I'm thinking it's a buck or less a foot. That might be cheaper than what a vacuum pump costs.
I don't know the current cost of vacuum hose but I'm thinking it's a buck or less a foot. That might be cheaper than what a vacuum pump costs.
Last edited by qtlow; Dec 13, 2016 at 10:01 PM.
Le Mans Master
Joined: Jan 2001
Posts: 6,718
Likes: 1,374
I would not recommend the air driven vacuum pump...
I had one of those and used it to evacuate and recharge a few of my vehicles when converting from r-12.... and it worked ok; however they are really noisy. AND it really put a demand on a small air compressor.
I would recommend the electric vacuum pump. It works better and QUIETER.
Also comes in handy while testing vacuum systems.
I would recommend the electric vacuum pump. It works better and QUIETER.
Also comes in handy while testing vacuum systems.
Hi Guys, I'm looking for something to help me in fix the C3 vacuum system when I can't test it with the engine running, like in these cold winter nights.
I've searched for a vacuum pump and found this air operated pump:
http://www.ebay.it/itm/3S-POMPA-del-...item210e7b7ba7
I wonder if I can use something like this or if an eletrical and more powerful one could be a better choise.
Thanks as usual!
I've searched for a vacuum pump and found this air operated pump:
http://www.ebay.it/itm/3S-POMPA-del-...item210e7b7ba7
I wonder if I can use something like this or if an eletrical and more powerful one could be a better choise.
Thanks as usual!
Burning Brakes
Joined: Apr 2008
Posts: 1,222
Likes: 93
From: shelbyville West Michigan
why not just get a hand vacuum pump, it's all I use when I test mine. they work just fine. $15 at harbor freight or spring for a better quality mity-vac.
you don't need to test the entire system at one go, just do one component at a time, follow Wilcox's instructions or do a search, I've posted diagrams and instructions as well several times.
you don't need to test the entire system at one go, just do one component at a time, follow Wilcox's instructions or do a search, I've posted diagrams and instructions as well several times.