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Discussion Starter #1
Installed a disc brake conversion kit from Inline Tube about a year ago. Everything went well, however the brakes didn't work as well as I expected. I new I had a low vacuum issue so I just dealt with it until recently. I only had 5" of vacuum going to the brake booster so I decided to get a vacuum pump. I installed it and hooked everything up and no difference. The pump automaticly shuts itself off at 20 inch of vac. When I put my finger over the hose going to the brake booster it works properly. When I hook it up to the booster it runs constantly. Is it safe to say I have a bad brake booster. Has anyone else worked with Inline tube, just wondering if they will swapp it out for a new one. Thanks
 

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My check valve was bad right out of the box. Pull it out of the booster and see if yours is the same. If you can blow through it in either direction then it's bad. You should only be able to blow through the side that plugs into the booster. If that's it, new ones are only a few bucks and they have them on the Help! aisle of most stores.

You can easily check the booster itself with a hand vacuum pump. Just get some tubing so you can connect the pump to the check valve (whether it's bad or not). Pump it until the gauge on the hand pump reaches 15-20" or so and leave it. It should hold for several hours if the booster and check valve grommet are good.
 

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Discussion Starter #3
Ok, pulled the check valve out. When I blow through the check valve (hose end) very little air can gets through, I can hear a slight hiss. When I blow through the booster side i can hear and feel the check valve open up. It is taking quit a bit of pressure to blow though from the booster side to open the check valve. Is it possible that the valve is hanging closed a bit?
 

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You shouldn't be able to blow through the hose side at all. You should be able to blow freely through the booster side.
 

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Discussion Starter #5
Thanks guys. I will pick up a new check valve tomorrow and see if it helps. I will post the results.
 

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Those hand vacuum pumps are cheap and come in really handy for bleeding brakes and checking vacuum accessories. Might as well grab one and a box of various vacuum t's so you can check out the booster while you're at it.
 

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Discussion Starter #7
Ok, bought a new check valve. I blew through it to compare it to the original and it does work better. I put it on, hooked up my hoses and theres no difference. The vacuum pump still runs constantly, so I must have a leak in the booster, I guess. Anyone else have any suggestions before I replace the booster. I did not check the booster with a hand pump because I figured if the pump is supposed to shut off and it's not than the booster is not holding vacuum. I can't find my receipt from Inline Tube so I guess I'm SOL. Any suggestions on where I should pick up a new one.
 

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Before you condemn the booster, hook up the hand vacuum to the booster, through the new check valve and all, just as if installed aith manifold vacuum going to it.

As Steiner suggests, the assembly should hold vacuum for most of the day.
If it leaks down, check the pedal rod is not holding the atmosphere valve open as in applying the brakes, should be a little slack between the pedal and booster, maybe a 1/16-1/8 inch. Might have to hook up a return spring on the pedal to keep it from 'riding' the booster.

I think you also need a vacuum reservior and the pump connected to the tank outlet to booster as I read the pump is connected to the manifold and cannot achieve a better vacuum - carb has holes - see them - open throttle plates. The manifold hose should be connected to the tank via check valve so under decel, vacuum from the engine is greater and helps 'supply' the tank with vacuum pressure by opening the check valve. At other times, idling, accelerating, the vacuum pump supplies the vacuum.

Vacuum boosters generally need a minimum of 13 inches of vacuum to function correctly.
 

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You said the pump turns off when you seal the tube, right?
Then the booster is bad.

Wait, you have the pump hooked up straight to the booster and nothing else right? There is no connection to the engine?
 

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Discussion Starter #10
Correct. The pump is not hooked up to anything else. I can put my finger over the hose and the pump turns off. Hook it up and it runs constantly.
 

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If you hook up the pump only to the brake booster, does the pump shut off?
 

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Discussion Starter #13
The brake booster is the only thing hooked up to the pump. It never stops running while it is connected to the booster. I can pull the hose off of the booster put my finger over the end of the hose and the pump shuts off in a matter of seconds. As long as the pump is hooked up to the booster it never shuts off.
 

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What pump and how long have you let it run? I'm tellin' ya....a hand vacuum will tell you right away if it's the booster or check valve grommet seal. Did you find anything with the brake pedal like Everett suggested? Those were some good ideas.
 

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Where are you at in NC? The wife and I were talking about taking a ride this weekend and I could take a look. I've got a hand pump.
 

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Discussion Starter #18
Ok, removed pedal linkage, rechecked with pump, still ran constantly. Hooked up my hand pump with the pedal linkage still disconnected and I can't get it to hold and vacuum at all. The hand pump is working properly, I checked it with my finger over the barb before I hooked it up to the booster.

Steiner... Thanks for the offer, I really appreciate it. I'm up in Stokesdale, it's a real small town North of Greensboro. The vacuum pump is a unit I purchased from Summit. The longest I have let it run is 5 min. I didn't want to push it much longer, I was afraid I would burn up the pump.
 

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Welp, there you go. Maybe Inline will work with you since it hasn't really been used.
 

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Discussion Starter #20
I'm not counting on Inline doing anything since I don't have my receipt. Any one have any recommendations on where to pick up a new one.
 
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