Hi,

I drive my 86 F250 XLT Lariat, 460cui, 2wd for 2 years now, without any brake issue at all yet, but:

does anyone know, if this is normal, that I hear inside (somewhere at the firewall/pushrod) that "hiss" sound?

I hear it everytime when I touch the brake pedal and push it down, just for the first 2inches until I feel the restistance point. When I feel the restistance and brake force is applied, the noise is gone.
I never lost brake pressure on the pedal and the pedal does also not move down, when I stand at the red light, so i just wonder if the sound is normal, or whether there might be some hidden danger, which could cause the brakes to fail suddenly.

thanks,
Greg

 

I had the exact same thing when I first got my truck. It was really bad to the point, where I had to "Pump up" the breaks. I found out that for me it was a bad master cylinder that had corrosion around the seals in the bore and did not seal properly so It would let fluid and air that was in the system pass by. I am guessing because of the bad seals I was never able to completely bleed the air from the system. I am guessing that is what makes the noise. When bleeding breaks with someone and building pressure it makes a similar noise. So I guess you might have air in the brake system causing that noise.

 

It is not normal and your brakes will not fail.
They may make you crap your pants, hard to push down or the pedal goes almost to the floor but on less something is already wrong with 1 half of the system and the 2nd half fails you will always have brakes.
You also have the park brake or E brake if you had to but that works just about as good as you dragging your feet.

On the hiss the booster is bad and will need to be replaced.
I had them hiss all the time your foot was on the pedal and always had brakes but I would not wait that long if you can help it.
The one on my truck when you stepped on the pedal would cause a vacuum leak that you could not hear but the motor would run ruff till you let up.
Dave ----

 

I guess I completely missed the mark. Your take makes way more sense. I thought he was talking about the noise that occurs when pushing the pedal with excessive travel. Should probably think more before I start writing...

 

thanks Dave
I guess you nailed it, as I realised also my engine runs rough on idle being on brake

looking on rockauto.com, which booster brand could you recommend?
I guess Cardone isn’t a bad choice?

 

I don't remember where I got my booster and master as I replace it at the same time because if you rest your foot on the pedal it would sink to the floor.

The booster & master came out of my parts truck that rolled over and was thinking it had to be good if the guy was using the truck when it rolled, guess not.
I was also converting my truck from non-power to power during the cab off frame rebuild.

I think I got the booster & master from the local Auto Zone as I was in a rush to get the truck on the road for my job's 60 year birthday & car show.
This way it was also easy to return the core on the booster, master was new so no core.

Some times you can get the booster & master as a set but I could not in my case.
Cardone is a good name but I have also heard they have been lacking.
So its a crap shoot on any parts we get now days.
Good luck
Dave ----

 

I had the same noise, but my brakes were squishy. I replaced the booster with a cardone, which helped but still hissed. I ened up having to replace the master cylinder to resolve the issue.

 

Drove my 82 from '93 to '16 before I replaced my booster, mine hissed but it only hissed when you turned the truck off you could hear the vacuum hissing out of the booster. Since I replaced it, it doesn't hiss anymore. Brakes didn't feel bad, and stopped no different than it did post booster replacement for me.

 

In my 82 F-250, I am hearing the hiss all of the time when the brakes are not pressed. As soon as I do press the brakes, the hiss is gone. My brakes are not very good right now, I have to press really hard and the calipers seem to be sticking for a few seconds after I let up. I looked at the two front hoses and they are undoubtedly factory, so I wonder if they are squeezing the fluid a little when you let off. Is the hissing until I hit the brakes a bad omen?

 

Brake parts for these trucks are cheap. IMO if you can see it, replace it...its the brakes we're talking about.

I also bought a motive power bleeder, since using it, after replacing MC, Booster, front brake lines and hoses, front calipers, the truck stops much better now.

 

For brake parts I try to get made in USA. Wagner, Raybestos, ACDelco, Motorcraft are domestic. Last few replacement parts I bought were Wagner. I believe Wagner makes a master cylinder for your truck.
Not sure where Cardone parts are manufactured.