Hydroboost issue?

Anyone have to replace a hydroboost unit because it was causing the brakes to drag?

Mine will just about bring the truck to a stop dragging so hard, then you hear a couple of pops out of the dash and the drag dissipates and the truck rolls free.

According to Identifix, the average mileage the problem occurs is about 82,000.

My hoopty is at about 194,000.

And before you start telling me to replace calipers, hoses, etc., I DID replace the hoses, and have disassembled all the calipers, cleaned and lubed the slides, de-rusted the bridges, new hardware, etc. Even cleaned & flushed the PS pump & system.

I could see a problem with the master cylinder causing it, but that wouldn't explain the popping noise right before it releases.

Factor in the popping noise, I keep coming back to the hydroboost unit.

Anyone else ever deal with this?
Hydroboost units don't really fail all that often in my experience. I've only had to replace two others EVER.. both on GMs, and both because the brake pedal wouldn't return..

Yes for gm twice sheared the power steering pump shaft sent metal through the system and on mine I just gravity and manually bled the system with new fluid mine was not as severe it was "sticky" and lacked pedal feel back until I left my driveway when it sat for more than 12 hours. It continues to be that way if I let it sit for more than a few days with out running and having the system used at all. How did you bleed your brakes after you replaced all those parts?
On my brothers dodge it had a bad line master to hydro boost that was partially collapsed and caused a similar situation that was non abs though.

I had a similar issue.I bled the entire system with fresh fluid,problem solved.

I bled the brakes with a Vacula.. good flow, clear fluid. Especially in the rear calipers.
The power steering thing got me to thinking..
these Ford power steering pumps use ceramic rollers, and my pump is getting weak..
makes sense that ceramic fines could find their way into the valves & stuff inside the unit..

Never seen this exact thing happen, but i have seen the hydroboost units fail fairly often. They usually end up leaking down the firewall in the cab. you usually dont know it until you look up under the dash.

quick update..
it got so severe I couldn't drive it..
parts are here as of yesterday..
There is something eff'd up with the hydroboost unit.. if you loosen the master cylinder nuts it releases.

Hydroboost unit is getting replaced.

I might replace the master cyl after dis-assembly and inspection of the bore..

I've eff'd up the rear brakes by continuing to drive it, so new pads & rotors.

I'm leaving for Texas tomorrow morning, so I wont have the opportunity to work on it for about a week..
Update with actual cause/cure when I get back..

Identifix has recorded 82,000 instances of the hydroboost unit failing causing this problem..

to the guys that told me to bleed the PS system..
Yeah. Did that. First thing I did.

I'm going to tear the old unit down when I get it off and figure out exactly what happened..
then I'll bag up all the parts and turn it in as a core!

Mine did the same thing....self-applied the brakes. Flush and all that..... did no good.
Replaced the unit....no problems since.......5 years ago.
Make sure you replace those little teflon seals on the line connections.

JLDickmon said:

quick update..
it got so severe I couldn't drive it..
parts are here as of yesterday..
There is something eff'd up with the hydroboost unit.. if you loosen the master cylinder nuts it releases.

Hydroboost unit is getting replaced.

I might replace the master cyl after dis-assembly and inspection of the bore..

I've eff'd up the rear brakes by continuing to drive it, so new pads & rotors.

I'm leaving for Texas tomorrow morning, so I wont have the opportunity to work on it for about a week..
Update with actual cause/cure when I get back..

Identifix has recorded 82,000 instances of the hydroboost unit failing causing this problem..

to the guys that told me to bleed the PS system..
Yeah. Did that. First thing I did.

I'm going to tear the old unit down when I get it off and figure out exactly what happened..
then I'll bag up all the parts and turn it in as a core!

Click to expand...

Just throwing it out there if that is your zip in the location for MI just had chevy 3/4 in the shop with a "hydroboost" issue so we thought. Turned out the bracket for the parking brake rotted out and kept binding/locking everything up did the same thing release the pressure or drive it would come and go then return after going around a corner straight lines had no issues. Had all the symptoms of a hydroboost but that was ok along with the master still replaced them cooked the pads, rotors, calipers and fluid the rotors got cherry red so the guy says would not surprise me though.

Problem resolved..
I'll post pictures later..

OK..
Master cylinder body.. aluminum..
Hydroboost body.. cast iron..
I live in a state where they use road salt in the winter time (may be a factor, may not be)..

The master cylinder was rotted onto the hydroboost unit.. When I finally got it off and air-hammered apart to retrieve the push rod, there was a shload of corrosion, rust, and assorted nastiness packed around the push-piston of the hydroboost unit, binding the piston.

My work truck started self applying the brakes at low speeds going over bumps

here's the crap.. here's the bore I dug it out of...