The Diesel Stop banner
1 - 20 of 21 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
Hi,

I have 1994, F350 Crew Cab Dully, with a 7.3L Turbo Diesel, non-power stroke

My brake pedal intermittently can be pushed to the floor board.

I have just replaced the master cylinder, one back brake line, new ABS Hydraulic Unit, new rear brakes, turned rotors, brakes in front good.

I do hear the air noise when I push down on the brake pedal when the engine is running.

At this point, the mechanic does not know what is wrong and can only suggest starting replacing parts like maybe the brake power booster or calibers.

Does anyone have suggestions where to look first or know a fix to this problem?

Thank you,

Kyle
 

Attachments

·
Registered
Joined
·
11,887 Posts
Could very well be the booster, they don't last forever. You weren't quite specific about the noise. If you hear the booster noise steadily with constant pressure on the pedal that would indicate a bad booster. Just a quick whoosh as you press the pedal is normal.
 

·
Registered
Joined
·
231 Posts
I'd bet on the brake booster being the problem.

The brakes on this truck when working properly are very good! My left brake was dragging a week or so ago and it was due to a sticking caliper. Normally I'm very anal about keeping up with brake maintenance but due to my laziness it had been three or four years since I'd changed out the brake fluid and it was getting quite dark indicating moisture had entered the system. The dragging caliper was the result.
 

·
Registered
Joined
·
1,847 Posts
You probably have air in the brake system. The reason the pedal moves when the engine starts is because the power brake booster gets vacuum, and begins to work.
 

·
Registered
Joined
·
11,887 Posts
As soon as you start the engine you have vacuum assist at the brake booster. In other words you've got power brakes with the engine running. If the pedal's real low generally the rear brakes need adjusting (if they're still drum brakes on a '94). Self adjusting brakes only halfway work, usually they needed a manual adjustment every year or two. And if the adjusting linkage is crudded up with age and neglect chances are they're not self-adjusting at all.
 

·
Registered
Joined
·
17,604 Posts
My '94 dually has drum in the rear, so the OP probably does too.
 
  • Like
Reactions: LMJD

·
Registered
Joined
·
7 Posts
Discussion Starter · #8 ·
1994 F-350 Diesel Pedal Intermediately goes to floor board then no brakes

If you can please give more suggestions, thank you

1994 F-350, 7.3L Turbo Diesel Non-power stroke, dually

Before starting the engine I press the brake pedal and it is hard. While still depressing the brake pedal I start the engine and I then have a low pedal.

Any ideas what causes this?

ADDITIONAL INFORMATION: I have recently put new brakes on rear, (Front are fine), turned rear rotors, one new brake line (not all replaced), new master cylinder, and a new ABS Hydraulic unit. I know the brake line has been bled many times unless there is another small hole in the brake line, in a different place that has not been found.

When driving the pedal sometimes goes to the floor board which makes the dually hard to stop. (it is not breaking right, therefore, at times can not stop the truck in normal braking distance.


P.S. We checked for air in line but do not find any. Trucks brake line been bleed probably 12 times
 

·
Registered
Joined
·
1,876 Posts
Readjust rears.

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

·
Registered
Joined
·
2,195 Posts

·
Registered
Joined
·
17,604 Posts

·
Registered
Joined
·
11,887 Posts
How did you adjust the rears?
 

·
Registered
Joined
·
2,195 Posts
If it does, it isn't factory.
That's my point. We need to know more about how the truck is built, especially if he's saying "rear rotors".

 

·
Super Moderator
Joined
·
26,503 Posts
If this thread looks a little fractured, it's because I consolidated replies to 3 different threads started by the OP here.

To Kyle3066: Please post your question in only one forum and continue the discussion there instead of making multiple posts in different forums.

Thanks
klhansen
Moderator
 

·
Registered
Joined
·
17,604 Posts
Thanks Kevin.
 

·
Registered
Joined
·
1,876 Posts
A whoosh isn't usually normal. That's normally a sign of a failing booster.
And yes, these only had rear abs.

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

·
Registered
Joined
·
2,195 Posts
Rear Antilock Brake system
That doesn't answer my question, or clarify your earlier statement about rear rotors.

A brake rotor is a brake disk, which is only used in a disk brake system, like this:



But your truck should have rear DRUMS, like this:



Which is on your truck?
 
1 - 20 of 21 Posts
Top