Brake problems

[wanderer]

Getting off of the interstate ramp this afternoon, my butt puckered up, as the brakes didn't work properly. Hard pedal, and it would stop, but the pedal slowly would go down.

Got it parked at my house, and popped the hood. Brake fluid reservoir is ok, and hardly any residue on the vacuum pump. I replaced the vacuum pump on 3-25-02. My gut feeling is that the vacuum pump has died again.

Any thoughts from anyone?

On edit, the truck is a 1996 F-250

 

[Mike]

Vacuum pump or possibly the brake booster diaphragm is kaput.

 

[wanderer]

How do you check for brake booster diaphragm problems?

 

[wanderer]

I pulled the vacuum hose off of the booster and stuck my thumb to it. It was sucking, so I went to the dealer and picked up a new booster. Didn't fix the problem. The booster was relatively easy to install. I suppose I'll buy a vacuum pump now.

 

[Mike]

Bummer, what did they gouge for a booster?

 

[wanderer]

Bummer, what did they gouge for a booster?

$141.00 I probably need to find a board that has more people that will answer technical questions concerning simple stuff like this. You are the only one who gave me any time. It's kind of ironic that the people who complained about TDS are here, and I assume have read this post, and still have no input for help. Says a lot about the state of things.

 

[Mike]

I probably need to find a board that has more people that will answer technical questions concerning simple stuff like this. You are the only one who gave me any time. It's kind of ironic that the people who complained about TDS are here, and I assume have read this post, and still have no input for help. Says a lot about the state of things.

Sorry more folks didnt respond to you sooner, it is a holiday weekend and traffic is down on the boards somewhat. I know its too late now but as for testing a brake booster, I've never done it before but I would think you could do it with one of those mighty vac hand pumps to see if it would hold a vacuum.................

 

[jharvey]

The vac pumps are POS's. Mine went at 90k and again at 140k. Got tired of replacing them so I replaced the truck

Sorry I didn't see this sooner, I've been out of the house for a day or so.

 

[wanderer]

I started to replace the vacuum pump first, but I felt suction at the booster, so I assumed I had a booster problem.

 

[wanderer]

I thought I would add an addendum to this thread. Although I had suction at the hose to the brake booster, it apparently wasn't sufficient to do the job. I bought a new pump today, or rather remanufactured, and the brakes are back to normal. I now have a used brake booster, that is good, that is in the garage, awaiting an individual who needs one.

 

[Big Red CC Dually]

I started to replace the vacuum pump first, but I felt suction at the booster, so I assumed I had a booster problem.

Sorry I didn't see this earlier...If the vacuum pump is good it will "suck your finger off your hand" ;p well, almost

The vacuum you felt is not enough to activate the booster, I seem to remember at least 20" Hg is required. A hard pedal and no stoppy is a sure sign of a bad vacuum pump. Of course you know that now though, sorry.

In edit: A soft pedal and spongy/no brakes is one sign of a bad master cylinder or booster.

Rick "COB"

 

[wanderer]

Thanks, I'll remember that now

I took the old pump to NAPA, and the guy behind the counter played with it and said that it seemed to be pumping to him too. I told him to give me a new pump anyway. When I was pressing the pulley on the new pump, I noticed the difference in how they both acted. I could spin the old pump relatively easy with the pulley, and it would sound like it was working, and it had some suction. The new pump was hard to turn by hand, and had some serious suction. I didn't think about it until your post, but I think I will take the hose off of the booster to feel what a good pump acts like.


This truck has been paid for since '98. I was pissed about spending money on it until I realized how cheap it is compared to a new one.

 

[Ggg]

IIRC The specs for a good pump it will pull about 23" of vacuum and the gage should be pretty steady. Anything less then 14" of vacuum or large fluctuations on the gage means the pump is bad.

 

[geonc]

$141.00 I probably need to find a board that has more people that will answer technical questions concerning simple stuff like this. You are the only one who gave me any time. It's kind of ironic that the people who complained about TDS are here, and I assume have read this post, and still have no input for help. Says a lot about the state of things.

Blair, sorry about your apparently neglected post!

Myself, I have been running dark to dark and just have enough time to briefly pop in and back out.

I may get tore up but the tech section at OB has only declined since the Super Duty site opend.

There are MANY daily posting members here that only post in Refinery/GGG/Lounge but take their tech posts over to SDD

I'm sure Maxx was looking out for members that thought OB was just a trash site and wanted something a little cleaner.

Too bad OB and SDD cannot merge

 

[Ggg]

I can understand wanting the two sites to merge, but for me it works out best with them completely separate. The computer I use at work is a municipally owned computer and Internet connection, so the taxpayers (me included) pay for them and as you can imagine there are some rather strict limitations on what can and can't be viewed. This site can not be viewed due to the GGG section, so I then go to the SDD site.