(hydroboost) brakes locking up at idle

BoostedSUV

BoostedSUV

Active member
Re: (hydroboost) brakes locking up at idle

Well I've been busy lately but I have been tinkering with Ty. I found the PS pump was leaking pretty bad from the resevoir so I bought a reman unit and replace it. I took all the lines off, blew them out reassembled everything. I fired the truck and the brakes locked up. I ran the truck at higher RPM and held the pedal back. After I few times I got the brakes to drag a little but they're not locked up. I took it for a ride and held the brake pedal back with my foot and its fine. The truck stops great when I apply the brakes but the drag a little if I don't hold the pedal back slightly with my foot.

One other issue I'm having is the eyelit of the HB push rod is too large for Mikes adapter so I have wayyy too much front and back play on the pedal. I think I'm going to cut the brake rod off the vac booster, thread it and use a coupler to attach it in place of the HB eyelit. Either that or I need to make some sort of collar to reduce the amount of play. I'm making progess but it's not there yet....
 
BoostedSUV

BoostedSUV

Active member
Re: (hydroboost) brakes locking up at idle

blackty said:
You only have 52 days...Jim
Click to expand...

That has been my inspiration to get my butt out in the shop and get to work! If I don't figure this thing out the next NASTE meet will be a wrench session at my house!!
 
nallj92

nallj92

Active member
Re: (hydroboost) brakes locking up at idle

try bypassing your cooler and just running the return back to the pump directly. I had issues and recently found it was the cooler making too much restriction in the return line, backing up the fluid into the spool valve causing it to stick partially applied/dragging the brakes.
 
BoostedSUV

BoostedSUV

Active member
Re: (hydroboost) brakes locking up at idle

nallj92 said:
try bypassing your cooler and just running the return back to the pump directly. I had issues and recently found it was the cooler making too much restriction in the return line, backing up the fluid into the spool valve causing it to stick partially applied/dragging the brakes.
Click to expand...

That's a good idea and something I've been thinking about. I also have an after market oil cooler I can put in place of the stock cooler if need. I think I'm going to try that this weekend. thanks for the idea. :tup:
 
Quickstop [UK]

Quickstop [UK]

Combating adversyty.
Re: (hydroboost) brakes locking up at idle

That is a great idea.

Another thought I had was the proximity of the line from the PS pump to the manifolds. I used the Russell powerflex Teflon hose and was wondering if they might be warped due to the heat. I guess I'd prob have a bigger leak if that were the case. I'd like to make a hardline instead at some point.
 
Aeroking

Aeroking

e.i.
Re: (hydroboost) brakes locking up at idle

Quickstop [UK] said:
Another thought I had was the proximity of the line from the PS pump to the manifolds. I used the Russell powerflex Teflon hose and was wondering if they might be warped due to the heat. I guess I'd prob have a bigger leak if that were the case. I'd like to make a hardline instead at some point.
Click to expand...

that always worried me cause mine runs along the crossover. I have the line in a firesleeve, but still it lays on the crossover. But mine hasnt leaked in 2 years. :roll: Is there a high-pressure PS pump available on the market?
 
BoostedSUV

BoostedSUV

Active member
Re: (hydroboost) brakes locking up at idle

Well I've be hustling on this truck trying to get it situated for upcoming NASTE. I made my pedal rod extension, reversed the lines off the master, bled everything and the brakes are still applying! I took the master cylinder off and the booster pushes out and I can't even push it back with a pry bar!! I swaped power steering pumps, hydroboost units, blew out the lines etc. I just can't get these friggen things to release with the truck running!! The only thing I haven't tried is bypassing the factory PS cooler but I'm doubtfull that's my issue. Anybody have any new ideas so I can get this truck to the event on Sunday???
 
M

MikeRenz

not stock
Re: (hydroboost) brakes locking up at idle

wait a second...how do you have the master mounted on the firewall? do you have it spaced out off the firewall at all? I wonder if the rod is just always pushing on the cylinder and applying the brakes
 
T

turboj91

New member
Re: (hydroboost) brakes locking up at idle

What's the travel length of the rod vs the travel length of the master piston?

BTW, no lauches yet. I still need to send you loops.
 
BoostedSUV

BoostedSUV

Active member
Re: (hydroboost) brakes locking up at idle

I've taken rod length measurments a few times to verify and I don't think that's my issue. As soon as I star the truck the brakes apply and I have little to no brake pedal travel. If I had a 6an coupler I would bypass the hydroboost but I think I would have a hard time stopping with out power assist.

I did make a 1/2 shorter rod and had the same issue. with the engine not running the brakes are fine, as soon as I add pump pressure they are applied and the truck barely moves. :rant:
 
BoostedSUV

BoostedSUV

Active member
Re: (hydroboost) brakes locking up at idle

I drove the truck to inspection station yesterday morning to get my collector emissions exempt decal and I felt the tuck fighting the brakes. When I got home all four wheels were covered in brake dust. I had read that driving it will purge the air and free them up but it did not.

When I got home I pull off the master cylinder and started the truck. The pedal fully depressed to the floor and with both hands I couldn't pull it back. Been fighting this for months now... I spent 6 hours detailing the truck in preparation for tomorrow... I'd really like to be able to get it there,,,,
 
P

Poconojoe

Donating Member
Re: (hydroboost) brakes locking up at idle

Did you try a master cylinder from a vehicle that originaly came with Hydro boost, like an Astro van or a diesel pick up?
Are you using a SyTy pump or an astro van one?
Have you checked the pump pressure?
 
BoostedSUV

BoostedSUV

Active member
Re: (hydroboost) brakes locking up at idle

Poconojoe said:
Did you try a master cylinder from a vehicle that originaly came with Hydro boost, like an Astro van or a diesel pick up?
Are you using a SyTy pump or an astro van one?
Have you checked the pump pressure?
Click to expand...

I would bet the truck on the fact that's not the master cylinder. I can take it off the truck and the hydroboost unit will pull the pedal to the floor and I cant pull it back with all my strength. It's the power steering pressure applying the brakes with the truck running.

I'm going to bypass it tonight and see if I can stop the truck with manual (bypassed hydroboost unit) brakes
 
TYTILIDIE

TYTILIDIE

METH HEAD
Re: (hydroboost) brakes locking up at idle

What application is your master cylinder from and what application is your hydraboost unit from?
 
STOUT74

STOUT74

Member
Re: (hydroboost) brakes locking up at idle

Seems your a little stuck. Did you call Van? Maybe time to give them a call instead of
:banghead:

This came from the FAQ's on Installation on the Vanco Website.

5. Check to make sure there is a little slack in the brake pedal. The Hydroboost pedal rod should not be depressed at all, and the brake pedal should have a little up and down jiggle.

WARNING: FAILURE TO ALLOW SLACK IN THE PEDAL ASSEMBLY WILL RESULT IN CONSTANT BRAKE ENGAGEMENT AND DAMAGE TO THE BRAKE SYSTEM

If proper slack cannot be obtained, contact Vanco at (323) 563-1588 about additional spacing schemes that are available. DO NOT OPERATE UNTIL CORRECTED.

Vanco Power Brake Supply
9738 Atlantic Avenue
South Gate, CA 90280
Phone: (323) 563-1588
Email: VANCOPBS@aol.com
Web page: vancopbs.com

Don’t hesitate to call “Van” with any questions or problems!
 
BoostedSUV

BoostedSUV

Active member
Re: (hydroboost) brakes locking up at idle

Just tried giving them a Cal.. Not that I thought I would get an answer on a Saturday. Mu stupid work hours make it hard to call any business.
 
BoostedSUV

BoostedSUV

Active member
Re: (hydroboost) brakes locking up at idle

First of all I want to thank Mike (Tytildie) for taking the time to trouble shoot with me over the phone and even go out in his garage to compare my results on his on Ty! If it weren't for him I wouldn't have found my issue! He got the wheels turning in my head and his suggestion of something to try pointed me in right direction!!! Thanks again Mike!!!


Ok so my problem was I had pressure in the "low pressure" return line coming out of the steering box. Not sure why but there was pressure backfeeding into the return of the hydroboost unit and causing the brakes to apply. When I disconnected the low pressure return on the HB unit and stuck the hose directly into the resevoir the brakes worked perfect witth the truck running. The steering box side blew fluid out the low pressure return clear across the garage! Not really sure why but it was with out a doubt putting pressure into the HB unit.

What I did was move the T from the steering box to the right before the resevoir return and it solved the problem. However I'd like to know why the steering box had so much pressure coming out of the "low pressure" line and causing this many month long headache!!!!
 
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