Brake pedal goes to floor when engine NOT running - Ford Truck Enthusiasts Forums



1999 to 2016 Super Duty 1999 to 2016 Ford F250, F350, F450 and F550 Super Duty with diesel V8 and gas V8 and V10 engines

Brake pedal goes to floor when engine NOT running

Reply
 
 
 
Thread Tools Search this Thread
  #1  
Old 01-17-2018, 11:18 AM
Campsta's Avatar
Campsta Campsta is offline
New User
Thread Starter
 
Join Date: Dec 2017
Posts: 17
Campsta is starting off with a positive reputation.
Brake pedal goes to floor when engine NOT running

So after a lot of searching and reading, I cannot find a thread where the brakes go to the floor when the engine is NOT running. They never gain back pressure no matter how many times I pump and I don't see any leaks externally.. Can this be a bad MC? All fluids are correct level as well.

Also, the pedal goes almost to the floor when its running. Its like it doesn't start braking until about 1 inch from the floor.

Another thing I noticed is that if I hold the brake pedal down, I can only turn the steering wheel about a quarter turn then it locks up. As soon as I let the pedal go, the steering frees up.
Reply With Quote
  #2  
Old 01-17-2018, 11:34 AM
bwguardian's Avatar
bwguardian bwguardian is online now
Senior User
 
Join Date: Dec 2007
Posts: 149
bwguardian is starting off with a positive reputation.
It would help tremendously to know what the mystery vehicle is...
Reply With Quote
  #3  
Old 01-17-2018, 11:48 AM
Campsta's Avatar
Campsta Campsta is offline
New User
Thread Starter
 
Join Date: Dec 2017
Posts: 17
Campsta is starting off with a positive reputation.
Sorry, it is a 2001 F-350 CC LB DRW Lariat LE 4X4 with the 7.3 and auto trans.
Reply With Quote
  #4  
Old 01-17-2018, 11:58 AM
bwguardian's Avatar
bwguardian bwguardian is online now
Senior User
 
Join Date: Dec 2007
Posts: 149
bwguardian is starting off with a positive reputation.
Your truck does not have a master cylinder. It operates off a hydroboost which also is linked to the steering. If power steering is low it can affect the hydroboost.
Reply With Quote
  #5  
Old 01-17-2018, 12:24 PM
Campsta's Avatar
Campsta Campsta is offline
New User
Thread Starter
 
Join Date: Dec 2017
Posts: 17
Campsta is starting off with a positive reputation.
Uuhhhh, I'm almost positive they still have a MC. They just don't have a brake booster, it uses the hydroboost like you stated.
Reply With Quote
  #6  
Old 01-17-2018, 12:38 PM
Mike189677's Avatar
Mike189677 Mike189677 is offline
Posting Guru
 
Join Date: Jan 2012
Posts: 1,553
Mike189677 has a very good reputation on FTE.Mike189677 has a very good reputation on FTE.Mike189677 has a very good reputation on FTE.
Your truck definitely a master cylinder it uses hydro boost instead of the vaccum boost so it doesnít have the vaccum booster mounted to the firewall.
Reply With Quote
  #7  
Old 01-17-2018, 02:38 PM
Campsta's Avatar
Campsta Campsta is offline
New User
Thread Starter
 
Join Date: Dec 2017
Posts: 17
Campsta is starting off with a positive reputation.
Quote:
Originally Posted by Mike189677 View Post
Your truck definitely a master cylinder it uses hydro boost instead of the vaccum boost so it doesnít have the vaccum booster mounted to the firewall.
Correct. I am leaning towards it being a bad MC but just wanted to see if anyone has had this problem. The steering locking up when braking is what is throwing me off..
Reply With Quote
  #8  
Old 01-17-2018, 07:35 PM
Mike189677's Avatar
Mike189677 Mike189677 is offline
Posting Guru
 
Join Date: Jan 2012
Posts: 1,553
Mike189677 has a very good reputation on FTE.Mike189677 has a very good reputation on FTE.Mike189677 has a very good reputation on FTE.
Sounds like a hyroboost problem not a master cylinder problem to me with the steering locking up while on the brakes. Maybe thatís why your thrown off looking at the master cylinder.
Reply With Quote
  #9  
Old 01-17-2018, 08:38 PM
Campsta's Avatar
Campsta Campsta is offline
New User
Thread Starter
 
Join Date: Dec 2017
Posts: 17
Campsta is starting off with a positive reputation.
Maybe I'll just change both lol. They are pretty cheap and not very hard to change.
Reply With Quote
  #10  
Old 01-18-2018, 03:01 AM
Mike189677's Avatar
Mike189677 Mike189677 is offline
Posting Guru
 
Join Date: Jan 2012
Posts: 1,553
Mike189677 has a very good reputation on FTE.Mike189677 has a very good reputation on FTE.Mike189677 has a very good reputation on FTE.
Quote:
Originally Posted by Campsta View Post
Maybe I'll just change both lol. They are pretty cheap and not very hard to change.
You could do that but you probably still have the same problem. I should have been more specific when I said I thought it was a hyroboost problem. Since both the steering and brakes are affected the power steering pump is the main suspect in my mind as it supplies hydraulic pressure to both the brakes and steering in the hydroboost system. How is the level and condition of the power steering fluid has it ever been changed though we are most likely past that point any leaks anywhere in the system?
Reply With Quote
  #11  
Old 01-18-2018, 03:36 AM
OneCylinder's Avatar
OneCylinder OneCylinder is offline
Senior User
 
Join Date: Sep 2014
Location: Jasper, Texas
Posts: 203
OneCylinder is starting off with a positive reputation.
How old are your brake pads? If they're worn, that would explain the low pedal. This might be a good time for a brake system overhaul. There's no such thing as being "TOO" safe.
Reply With Quote
  #12  
Old 01-18-2018, 07:00 AM
Campsta's Avatar
Campsta Campsta is offline
New User
Thread Starter
 
Join Date: Dec 2017
Posts: 17
Campsta is starting off with a positive reputation.
Quote:
Originally Posted by Mike189677 View Post
You could do that but you probably still have the same problem. I should have been more specific when I said I thought it was a hyroboost problem. Since both the steering and brakes are affected the power steering pump is the main suspect in my mind as it supplies hydraulic pressure to both the brakes and steering in the hydroboost system. How is the level and condition of the power steering fluid has it ever been changed though we are most likely past that point any leaks anywhere in the system?
Couldn't find any leaks on the steering or brake side. The fluid looks "ok" but I might just try a flush to start with because I don't know when the last time it was changed. The truck is new to me, and has 259k.
Reply With Quote
  #13  
Old 01-18-2018, 07:03 AM
Campsta's Avatar
Campsta Campsta is offline
New User
Thread Starter
 
Join Date: Dec 2017
Posts: 17
Campsta is starting off with a positive reputation.
Quote:
Originally Posted by OneCylinder View Post
How old are your brake pads? If they're worn, that would explain the low pedal. This might be a good time for a brake system overhaul. There's no such thing as being "TOO" safe.
The pads are in pretty good shape. I don't think it would be just the pads that would make the steering lock up as well.

But I agree 100%, cannot be too safe when it comes to brake systems! Especially when these trucks are (mostly) used to haul big loads.
Reply With Quote
  #14  
Old 01-18-2018, 03:35 PM
Batman7777 Batman7777 is offline
Senior User
 
Join Date: Sep 2016
Posts: 117
Batman7777 is starting off with a positive reputation.
I had that happen a few years ago and found out the engine must be running for the pump to work. Diesel's use a separate pump since it is a diesel and doesn't have gas engine vacuum. There could be a leak in one of the lines if the engine is running and you still don't have brakes/power steering.
Reply With Quote
  #15  
Old 01-18-2018, 09:15 PM
fonman fonman is offline
New User
 
Join Date: Nov 2017
Location: MI
Posts: 18
fonman is starting off with a positive reputation.
Ok, I am not an expert on hydro boost, but it’s an assist. The brakes have to work properly without it. You may have to “use both feet” to stop though.

All that said, if the pedal goes to the floor you most likely have air or a bad MC. Was it like this when you got it? If so could be either. If it was fine and just crapped, then the MC. All this assumes you would have noticed a leak.

My drill is to fix the obvious and see whats left. AKA fix the low pedal and then see if there is still a steering problem.
Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Brake Pedal still going down close to the floor... redbug 1999 - 2003 7.3L Power Stroke Diesel 12 01-02-2018 06:56 AM
Brake pedal goes to floor only when engine running Fords412 1999 to 2016 Super Duty 21 10-01-2017 10:10 PM
Help - E350 brake pedal goes to floor - only when running! Fords412 1968-2013 Full Size Vans 16 11-17-2016 03:31 PM
Power steering won't work. Brakes sometimes also. agg_bagg 1999 - 2003 7.3L Power Stroke Diesel 3 09-06-2016 06:28 AM
High Idle / Brake question / Power Steering cpye2 1999 - 2003 7.3L Power Stroke Diesel 17 03-10-2016 10:40 AM


Go Back   Ford Truck Enthusiasts Forums >

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump


All times are GMT -5. The time now is 06:42 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.