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Vacuum pump for brakes?

CherryK5

CherryK5

1/2 ton status
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So my cam doesnt make enough vacuum at idle, which means... no brakes.
Whenever i decend a hill or im just crawling around i need some brakes!

I have plenty of electric vacuum pumps that will make the required 16lbs of vacuum 9as opposed to my 8-10 i make at idle. =]) but i need to know what else there is to making that work with my brakes. can i hook it right up and be could to go or does it need some kind of regulator? it wouldnt be hard to hook it to my brake switch so it only kicks on when i hit the brakes, could that work?

Edit: Im asking specifically how to make this work, not on how to get the best set up.
 
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Time for hydroboost! Super easy, almost bolt in swap. If you find a good working unit from a junk yard, pick up a new power steering-to-hydroboost and hydroboost-to-gearbox hoses and a barbed "T" fitting, you'll have it swapped in under an hour if you're lazy and for 80 bucks or less.

If you really want to keep the vacuum booster, you could add a vacuum reservoir. Its a big coffee can looking thing with a check valve. Plug your booster into it, then it to the manifold or vacuum pump.

But I really recommend the Hydroboost set up. I love how the pedal is so responsive and gives a totally linear feeling compared to the vacuum booster. Strong enough to lock up all 4 37" tires any time I want, too. Feels even better when crawling around on the rocks and you're trying to modulate the brakes.
 
Amtek said:
Time for hydroboost! Super easy, almost bolt in swap. If you find a good working unit from a junk yard, pick up a new power steering-to-hydroboost and hydroboost-to-gearbox hoses and a barbed "T" fitting, you'll have it swapped in under an hour if you're lazy and for 80 bucks or less.

If you really want to keep the vacuum booster, you could add a vacuum reservoir. Its a big coffee can looking thing with a check valve. Plug your booster into it, then it to the manifold or vacuum pump.

But I really recommend the Hydroboost set up. I love how the pedal is so responsive and gives a totally linear feeling compared to the vacuum booster. Strong enough to lock up all 4 37" tires any time I want, too. Feels even better when crawling around on the rocks and you're trying to modulate the brakes.
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Im always pressed for time and money. So no hydroboost unless it comes in to our yard on something totalled out. And a vacuum canister wont make more vacuum. Just more volume. Been there.

And I can lock up the 35's effortlessly, but only on the first cycle of the brakes. It empties the canister out and then im back to two footing the brakes. And with a carbed motor im not gaining anything with hydroboost when my motor stalls or floods. Which is another thing that happens often.
 
Amtek said:
If you really want to keep the vacuum booster, you could add a vacuum reservoir. Its a big coffee can looking thing with a check valve. Plug your booster into it, then it to the manifold or vacuum pump.
Click to expand...

I have one of these at my parents house I think if its still there you can have it just pay for the shipping on it. I had it on my blazer with the cammed 350 and it seamed to help some what its worth a shot.
 
texas4x4rebel said:
I have one of these at my parents house I think if its still there you can have it just pay for the shipping on it. I had it on my blazer with the cammed 350 and it seamed to help some what its worth a shot.
Click to expand...

I appreciate the offer, but I already have two stock ones on there. Like I said. I need more vacuum, not more volume.
 
I know this is a stupid question, but you do have check valves inline right?
There should be one build into the line going to the brake booster.
Its easily enough checked.

Just run the truck until the booster should have maximum vacuum, turn it off, wait a few minutes and then try the brakes with the engine still off.
You should have full boost for a couple of pumps.
If not, then the check valve is leaking or nonexistent.

The cannisters should use that check valve too.
The line from the canister to the booster should hook up between the booster and its check valve.
That way the cannister holds its vacuum when the engine is off.
 
Fordum said:
I know this is a stupid question, but you do have check valves inline right?
There should be one build into the line going to the brake booster.
Its easily enough checked.

Just run the truck until the booster should have maximum vacuum, turn it off, wait a few minutes and then try the brakes with the engine still off.
You should have full boost for a couple of pumps.
If not, then the check valve is leaking or nonexistent.

The cannisters should use that check valve too.
The line from the canister to the booster should hook up between the booster and its check valve.
That way the cannister holds its vacuum when the engine is off.
Click to expand...

That's exactly what it does. The canisters work fine and do their job. But at idle, going down hill, or in the rocks, those canisters deplete and then im back to having no brakes.

I really just need to know what I need to make the vacuum pump work.
 
I really just need to know what I need to make the vacuum pump work.
Click to expand...

Yep, I figured you did, but I've never worked on one. But a lot of diesels use them, surely it can't be too hard to find a diesel Blazer that uses vacuum brakes instead of Hydroboost.

As for hooking it up, failing finding a setup already on a truck, I don't see why it should be too hard.
I would just hook it between the check valve and the booster, leaving the canisters in place.
Then run it off a relay which is switched by a vacuum switch, powered by the accessory terminal of the ignition switch.
Let it work like an onboard air pump with a tank. It comes on, pumps down to a certain vacuum and shuts off.
Don't try to make it on-demand. It can't possibly respond fast enough to give you boost if you need it quick.
 
Fordum said:
Yep, I figured you did, but I've never worked on one. But a lot of diesels use them, surely it can't be too hard to find a diesel Blazer that uses vacuum brakes instead of Hydroboost.

As for hooking it up, failing finding a setup already on a truck, I don't see why it should be too hard.
I would just hook it between the check valve and the booster, leaving the canisters in place.
Then run it off a relay which is switched by a vacuum switch, powered by the accessory terminal of the ignition switch.
Let it work like an onboard air pump with a tank. It comes on, pumps down to a certain vacuum and shuts off.
Don't try to make it on-demand. It can't possibly respond fast enough to give you boost if you need it quick.
Click to expand...

Got a link for a vacuum.switch? I couldn't find any for somethin other than a vacuum cleaner.
 
No problem, just get a pressure switch and hook it up backwards...........:D

Well, when I read this, I thought, sure, see them all the time.
And when I started looking, I found plenty.
But wow, do they get good money for them.

I found this. http://www.omega.com/pptst/PSW21_PSW22.html
[FONT=Verdana, Arial, Helvetica, sans-serif] PSW21T[/FONT] should work. But its high.

I'll keep looking.
 
you really just need a vacuum switch to activate a relay that turns the vacuum pump on...
 
Id order one from a company like ssbc, they sell complete kits for your exact problem, the only problem is the price, they want 277 for the complete kit with relay, pump, etc..Im sure you could call them and order the switch and relay...

link: http://www.autoanything.com/brakes/69A3151A0A0.aspx
 
You don't want a flow through. Just a dead end switch on a "T" to read total system vacuum.
I don't know when the stock transmission switch switches, but the one for sale there was adjustable, which is what you need.

If you get an adjustable switch, I would set it as low, or high, depending on how you look at it, so that it does not switch until maximum vacuum.
Let the pump run for a few minutes, and if it does not cut off, adjust the switch slowly until it cuts off, and then go just a little farther.

That should give you maximum practical vacuum for that pump.

Then, test the brakes to see if its enough.
 
Fordum said:
You don't want a flow through. Just a dead end switch on a "T" to read total system vacuum.
I don't know when the stock transmission switch switches, but the one for sale there was adjustable, which is what you need.

If you get an adjustable switch, I would set it as low, or high, depending on how you look at it, so that it does not switch until maximum vacuum.
Let the pump run for a few minutes, and if it does not cut off, adjust the switch slowly until it cuts off, and then go just a little farther.

That should give you maximum practical vacuum for that pump.

Then, test the brakes to see if its enough.
Click to expand...

I can look up the stock on/off and see if it will work. The junkyard is full of them.
 
I can look up the stock on/off and see if it will work. The junkyard is full of them.
Click to expand...

That would work. At the worst, if the vacuum setting is right, you might have to reverse wire the relay so that the pump comes on when the relay turns off if the switch works wrong.

Gotta head home, I'll check back in later.
 
Fordum said:
Yep, I figured you did, but I've never worked on one. But a lot of diesels use them, surely it can't be too hard to find a diesel Blazer that uses vacuum brakes instead of Hydroboost.
Click to expand...

Never seen a factory GM diesel that used vacuum brakes. A lot of them have vacuum pumps but are used to run accessories like cruise control and such. I would be surprised if they could effectively run a braking system.
 
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