No Brakes !!! Hard pedal no power at all.

[912504x4]

This morning I drove my truck to the 1st stop sign like usual and coasted right through it. The pedal is hard and acts like it will stop the truck but the brakes have almost no affect on stoping the truck.
I pulled the vacuum line that goes into the booster and it is making some vacuum but I am not sure how much to look for. ( I have a gauge )
The resevoir is full of fluid.

What is the problem? Booster or bad vacuum pump? Maybe something else?

Thanks, Eric

 

[Doc]

Sounds like the vacuum pump to me. If memory serves me, you need to pull about 11 - 12 lbs of vacuum. Even with it pulling good vacuum, check to see how far it drops when you apply the brakes with the engine idling and how fast it recovers after releasing the brakes.

 

[Mr_Roboto]

Vacuum pump is a lot more likely than the booster.

"Disconnect the vacuum line at the booster and insert the gauge in the hose end and measure for the following minimum inches of Hg (mercury) depending on altitude:
15,000 Ft = 11.5",
10,000 Ft = 14",
5,000 Ft = 17".
Sea level = 21"."

 

[912504x4]

lol

What sea-level do you think St.Louis Missouri is at ?

Never had to think about that before.


Thanks,
Eric

 

[tuckerd1]

What sea-level do you think St.Louis Missouri is at ?

Never had to think about that before.


Thanks,
Eric

500' +/- 100'

 

[912504x4]

ah ha

must be defective pump. It never reached 10"

Where can I find one cheap cheap cheap?

Thanks,
Eric

 

[Exekiel69]

Jyard or pay $69 at autozone for a rebuild one.

 

[jauguston]

Before you buy a vacuum pump did you make the gauge connection right at the pump or was there some hose going to it you connected to. Could be a leaky hose.

Jim

 

[912504x4]

nah

The vacuum gauge showed that it kept the vacuum it reached even after I shut the truck off. For about 2-3 minutes anyway it held then it started to slowly lower.
I figured that would be normal to a vacuum system.

I ordered a used one from the local boneyard. The cheapest around me rebuilt was $99.00 at the zone.

Thanks,
Eric

 

[MIDNIGHT RIDER]

I have never had a vacuum pump go bad; and I run two, one to the truck, and one to the trailer brakes.

I have had three booster diaphragms go out and act exactly like what you describe.

A bad booster will be like trying to push the brake-pedal through a concrete floor, with very little braking effectiveness.

 

[Agnem]

And I on the other hand have replaced many pumps and zero boosters. I've said this for years, and I'll keep saying it. When your putting in good gauges, for oil pressure, temp, pyro, whatever. A VACUUM gauge is just as critical. It's the only way to tell your pump is going out before it becomes a crisis, and we all know you don't stop without good vacuum. Here's the thing... most bad pumps will create just as much vacuum as a good pump. The problem is it takes them longer to do it. The only way you'll get familiar with how long it takes, is to be looking at it all the time. When your pump is going, you will know it because of the way the gauge is behaving. Not by the way the brakes feel. You'll also know about leaks as they occur. Install the gauge! Get this one.

 

[Squirreltow]

I have a similar problem right now, but I am holding about 21 at the booster at idle.
So how can we tell whether I should look at the vacuum pump as going bad or just start at the booster?

Mel- I have already ordered a vaccum gauge to install in my pod.

 

[Agnem]

Chris, generally I can tell by pumping the brake and watching the gauge. If the pump is shot, you'll go to zero vacuum in a pretty big hurry. You should also be able to go from zero to 23" in about 5 seconds at idle. Slightly longer if you have cruise and a soup can. If it's the booster, you'll see the vacuum continue to drop with your foot on the brake and no pumping.

 

[Squirreltow]

Now when I went out and put the vacuum tester on the hose at the booster, it will only get to about 15 and it takes 30 seconds to climb up to that level.
I have a new pump that just arrived, I just need to get a P/S pulley puller or buy a new pulley.

What is the best way to get the pulley back onto the new pump??

 

[towcat]

What is the best way to get the pulley back onto the new pump??

long bolt, nut, and a couple of washers. bring pump down to the hardware store with you and find the right size and pitch bolt that threads into the shaft nose. oh yea, a little grease help things too.