ifrythings
Full Access Member
Disclaimer: Like anything on the internet that you read or follow it is at your own risk, Oilburners nor I will be responsible if you screw up, it is up to your discretion if your able to perform this job with your skill level and tools.
If your in my situation where your hydroboost is leaking from the power piston and running out from between it and the master cylinder and a reman unit is $500+ and tax on top of it or you got a junkyard unit (like I did) and want to freshen it up for around $50, read on.
This guide should be applicable for all hydroboost units, not just Ford as all units seem to be the same design with a few little odds and ends changed here and there.
Note: If your accumulator is loose (the blue or gold canister on the side of the unit) I have no idea where you can get new ones but you can rob one off of any unit in the junkyard thats tight on it's unit. Blue and gold have different pressures from my research, so only use blue in blue applications and gold in gold applications. (Mine was toast and I stoled one off a chevy truck somewhere in the 2000 ish year range)
I had a relatively stiff peddle which felt like manual brakes but with balls when you pushed hard enough on it, the leaking power piston was the cause of this as now it feels closer to how vacuum assists feels and no more leaks!
Note2: If your brake peddle sucks right to the floor when you start your truck up and you HAVEN'T taken the unit apart yet, this most likely will NOT fix it. If you did take it apart and it worked properly before but doesn't now, you more then likely don't have the lever assembly hooked up to the spool valve properly or at all.
The parts:
I order: NEW COMPLETE HYDRO BOOSTER HYDRO-BOOST REPAIR REBUILD KIT 2771004 ALL MODELS There are other cheaper kits out there but they only come with seals, no spring retainer or check valves and other non used parts for this unit.
A clean well lit work space is essential for this repair, no working on the lawn, you'll loose everything. A bench vise is recommended but not absolutely required, a big c-clamp will work also to remove the accumulator, brake clean or solvent to clean the parts and your basic wrenches and picks are all you need.
To begin, pump your break peddle 5 to 6 times to discharge the accumulator, place some rags under the booster and the power steering pump.
You should be looking at this now:
Now take a 9/16" or 14mm wrench or socket and remove the 3 nuts holding the master cylinder on (the left stud has 2 nuts on it, one holds a bracket holding the brake lines, you may or may not have this)
Nuts removed, master cylinder starting to separate.
Pull the master cylinder away and set it out of your way without bending the lines. ( you can see the relief in the boost thats full of atf)
Reference pic, nothing to do here.
Now disconnect the two high pressure lines using line wrenches, one is 5/8" and the other is 11/16" and the low pressure return line from the booster. The remaining fluid in the low pressure line drained back into the power steering pump on my truck and over filled it, it may not do this on yours.
Now heading into the cab, you'll have 4 nuts to remove on the firewall, they are 9/16" or 14mm
Now looking at your break switch, remove the red clip and slide everything off to the left, you can do this before removing the last nut on the firewall. (yes I know the brake switch is upside down in this pic, I did put it on correctly when reassembled)
Remove the unit from the truck and place it port side down in something suitable to drain the remaining fluid, theres a fair amount left inside.
Placing it top end up you can remove the lower boot retainer strap and the boot if it's flexible enough.
Now comes the fun part, according to the instructions this is a stake pedal rod that is non serviceable and unit replacement is the only
alternative, that does not vibe in my books so I used a 3/8" extension and some sockets stacked to make a leaver through the eyelet end to pull it out of the stake (sorry no pic of the setup) If you can not get the rod off it just means you can't replace the input shaft seals which if their not leaking and don't get banged up/cut while you do everything else you probably be alright.
Rod removed.
You do NOT need to do these next few steps as removing the mounting plate is not necessary or needed unless your swapping plates or making your own custom plate.
Remove snap ring.
Using a hammer pound out 2 of the studs to make room for your wrench.
Crescent wrench removing nut with serrations on the bottom, this is torque to 100 ft-lbs so it's tight.
What you should be left with now.
Now if you didn't remove the mounting plate, continue on from here.
Removed parts in line up of removal.
If your in my situation where your hydroboost is leaking from the power piston and running out from between it and the master cylinder and a reman unit is $500+ and tax on top of it or you got a junkyard unit (like I did) and want to freshen it up for around $50, read on.
This guide should be applicable for all hydroboost units, not just Ford as all units seem to be the same design with a few little odds and ends changed here and there.
Note: If your accumulator is loose (the blue or gold canister on the side of the unit) I have no idea where you can get new ones but you can rob one off of any unit in the junkyard thats tight on it's unit. Blue and gold have different pressures from my research, so only use blue in blue applications and gold in gold applications. (Mine was toast and I stoled one off a chevy truck somewhere in the 2000 ish year range)
I had a relatively stiff peddle which felt like manual brakes but with balls when you pushed hard enough on it, the leaking power piston was the cause of this as now it feels closer to how vacuum assists feels and no more leaks!
Note2: If your brake peddle sucks right to the floor when you start your truck up and you HAVEN'T taken the unit apart yet, this most likely will NOT fix it. If you did take it apart and it worked properly before but doesn't now, you more then likely don't have the lever assembly hooked up to the spool valve properly or at all.
The parts:
I order: NEW COMPLETE HYDRO BOOSTER HYDRO-BOOST REPAIR REBUILD KIT 2771004 ALL MODELS There are other cheaper kits out there but they only come with seals, no spring retainer or check valves and other non used parts for this unit.
A clean well lit work space is essential for this repair, no working on the lawn, you'll loose everything. A bench vise is recommended but not absolutely required, a big c-clamp will work also to remove the accumulator, brake clean or solvent to clean the parts and your basic wrenches and picks are all you need.
To begin, pump your break peddle 5 to 6 times to discharge the accumulator, place some rags under the booster and the power steering pump.
You should be looking at this now:
You must be registered for see images attach
Now take a 9/16" or 14mm wrench or socket and remove the 3 nuts holding the master cylinder on (the left stud has 2 nuts on it, one holds a bracket holding the brake lines, you may or may not have this)
You must be registered for see images attach
Nuts removed, master cylinder starting to separate.
You must be registered for see images attach
Pull the master cylinder away and set it out of your way without bending the lines. ( you can see the relief in the boost thats full of atf)
You must be registered for see images attach
Reference pic, nothing to do here.
You must be registered for see images attach
Now disconnect the two high pressure lines using line wrenches, one is 5/8" and the other is 11/16" and the low pressure return line from the booster. The remaining fluid in the low pressure line drained back into the power steering pump on my truck and over filled it, it may not do this on yours.
Now heading into the cab, you'll have 4 nuts to remove on the firewall, they are 9/16" or 14mm
You must be registered for see images attach
Now looking at your break switch, remove the red clip and slide everything off to the left, you can do this before removing the last nut on the firewall. (yes I know the brake switch is upside down in this pic, I did put it on correctly when reassembled)
You must be registered for see images attach
Remove the unit from the truck and place it port side down in something suitable to drain the remaining fluid, theres a fair amount left inside.
You must be registered for see images attach
Placing it top end up you can remove the lower boot retainer strap and the boot if it's flexible enough.
You must be registered for see images attach
Now comes the fun part, according to the instructions this is a stake pedal rod that is non serviceable and unit replacement is the only
alternative, that does not vibe in my books so I used a 3/8" extension and some sockets stacked to make a leaver through the eyelet end to pull it out of the stake (sorry no pic of the setup) If you can not get the rod off it just means you can't replace the input shaft seals which if their not leaking and don't get banged up/cut while you do everything else you probably be alright.
Rod removed.
You must be registered for see images attach
You do NOT need to do these next few steps as removing the mounting plate is not necessary or needed unless your swapping plates or making your own custom plate.
Remove snap ring.
You must be registered for see images attach
Using a hammer pound out 2 of the studs to make room for your wrench.
You must be registered for see images attach
Crescent wrench removing nut with serrations on the bottom, this is torque to 100 ft-lbs so it's tight.
You must be registered for see images attach
What you should be left with now.
You must be registered for see images attach
Now if you didn't remove the mounting plate, continue on from here.
Removed parts in line up of removal.
You must be registered for see images attach
Last edited: