Chasing Vacuum Gremlins
Thread Starter
Instructor
Joined: Apr 2009
Posts: 114
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From: Bradenton, FL
Chasing Vacuum Gremlins
I need some help understanding a vacuum issue I am having. I bought a vacuum pump to help resolve the issue. The pump is generating 17" of vacuum and I have 17" coming out of the vacuum tank when the pump is running.
Here is where it gets interesting! The line that comes out of the tank goes into a T where one line goes to the headlight vacuum relay and the other line connects to a T that feeds the heater mechanism etc. As mentioned I have 17" coming off the line out of the tank that feeds the tee but I can barely get 1" on any of the lines off that tee. If I feed either one of lines by themselves directly off the tank i get the full 17". Can someone help me understand why the vacuum drops so drastically when using the T?
Here is where it gets interesting! The line that comes out of the tank goes into a T where one line goes to the headlight vacuum relay and the other line connects to a T that feeds the heater mechanism etc. As mentioned I have 17" coming off the line out of the tank that feeds the tee but I can barely get 1" on any of the lines off that tee. If I feed either one of lines by themselves directly off the tank i get the full 17". Can someone help me understand why the vacuum drops so drastically when using the T?
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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Try http://www.corvette-101.com/vacuum.htm after testing all the componets then go to Willcox (on the left) and see if you can figure it out from there.
Thread Starter
Instructor
Joined: Apr 2009
Posts: 114
Likes: 1
From: Bradenton, FL
Using the T's there is not enough vacuum to operate anything. If I run a straight line to the headlights no problem I get plenty of vacuum. I have bought new T's and used those thinking it was clogged or cracked. I will post some pictures this weekend. I know that will make it easier to comprehend. Thanks for the replies and keep the suggestions flowing.
Safety Car
Joined: Apr 2000
Posts: 3,802
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From: Wichita KS
Buy yourself a package of vacuum caps is various sizes and unplug one side of the T at a time and cap it and test. See if a leak in one side is affecting the entire section. It should not drop from 17 inches to 1 inch.
There should be 3 ports on the vacuum tank. One is smaller than the other two so make sure that one has the larger hose from the check valve on it. That hose is smaller in diameter than the hoses for the headlights and wiper door.
If you have only one headlight relay then there is probably only two ports on the vacuum tank but one will still be smaller than the other.
cc
There should be 3 ports on the vacuum tank. One is smaller than the other two so make sure that one has the larger hose from the check valve on it. That hose is smaller in diameter than the hoses for the headlights and wiper door.
If you have only one headlight relay then there is probably only two ports on the vacuum tank but one will still be smaller than the other.
cc
Instructor
Joined: Sep 2008
Posts: 222
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From: penngrove ca
You are the right track. Isolate each component test and move back to the source.
I think one of the better tools I have is the $30 mighty vac. hand pump. With the hand pump I was able to isolate and test all the components.
I think I spent like $20 on misc. plastic fittings (T's, couplers, reducers etc.) and vac. hose. You will end up with extra stuff but it sure cuts down on the frustration of solving problems.
I think one of the better tools I have is the $30 mighty vac. hand pump. With the hand pump I was able to isolate and test all the components.
I think I spent like $20 on misc. plastic fittings (T's, couplers, reducers etc.) and vac. hose. You will end up with extra stuff but it sure cuts down on the frustration of solving problems.
