Hydro boost Failure Opinion
 

Based on pics....hydroboost failing?

No steady drip; no fresh fluid/leakage. Brake fluid reservoir full; power steering fluid reservoir full. No noticeable change in fluid levels.

when applying brakes, my brake pedal is soft/quasi spongy; it also travels a considerable amount.

Brake pads have plenty of life.

Im looking at purchasing one of the rebuild kits off of eBay and redoing the deals on the hydroboost.

Looking for a 2nd opion regarding hydroboost failing. Anything else I should check or look for?


https://cimg1.ibsrv.net/gimg/www.hum...2e00191845.jpg


https://cimg7.ibsrv.net/gimg/www.hum...0f139d9a36.jpg


https://cimg8.ibsrv.net/gimg/www.hum...4993a1aa45.jpg


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I also pumped the brake pedal 10 times while the engine is off. Pedal gets harder to press, but not super stiff to the point where you can’t keep pressing it down.

Afterwards, I started the truck while keeping my foot in the brake pedal. The pedal did not move at all. I just felt a “kickback.”

I ran through this procedure twice after taking the pics.

https://www.brakeandfrontend.com/ope...ssist-systems/


I found these online. After watching the video, i think I may have applied too much pressure to the brake pedal. I will try again tomorrow.

My goal here is to rule out possible causes before tearing into the hydroboost unit. I don’t have much experience with a hydroboost.

I just went thru all of this. I rebuilt the hydro boost unit only to have to replace it with a new one a month or so later. In my opinion, its not really worth the difference considering what might happen if it fails. The units are designed with an accumulator that would be good for 1 hard stop if the system fails.

I also replaced the master cylinder. It caused me to have to bleed the ABS, which required a scanner tool to do so. The tool can be rented so its not that bad. While I was at that, I replaced the rubber flex hoses with stainless braided hoses. The back brakes where they 'tee' was a nightmare but other than that it was an easy job.

I now have a truck that will stop on a dime.

Tim

If the brake fluid is very dark it is likely that it has never been flushed/changed. Most do not bother but it should be changed every couple of years. Over time the fluid absorbs water and other impurities. If the Hydroboost is not leaking I would not mess with it. The rebuild kits are cheap but they are also very easy to not get just right and then you have to do it all over again. I did rebuild mine and it is still holding 6 months or so later but only time will tell.

My thing was that it was a slight pain in the ass to remove the unit the 1st time, so after that I went new. I had previously changed out my brake fluid when I went with new pads and rotors, it was black. Now after everything was replaced, the fluid is still almost as clear. I think it took the ABS bleed procedure to get it all out. The new master cylinder made the biggest improvement.

Tim

You read my mind! I was wondering what item out everything you did yielded the biggest difference.

Im going to check my brake lines and possibly replace with stainless braided.

Then, do a full brake fluid flush. You mentioned a scan tool is needed. I have one....do you just select some kind of feature/activation under the brake menus? I had thought I could just loosen the screw on the caliper while pressing the brake pedal.

It’s definitely time for a brake fluid flush....just given the amount of time I have owned it. Fluid didn’t look dark, but you never know what’s in the lines/calipers.

“as they say, if it ain’t broke, don’t fix it”
That’s what puzzles me the most about the brake pedal feel. I see no current leaks/seepage. Prior owner definitely had a leak bc there is caked up oil/dirt/junk down the side of the fender well area/actual frame.

I cleaned up the area in the pics to give me a clear surface to hopefully detect a leak.

I doubt most scan tools will have the ABS module bleed function other than maybe the very expensive Snap-On one. GM Tech2 has a lot of functions that are very specific to GM and are only found on a Tech2 (or GM MDI using Tech2Win).

So, i pumped the brakes again today, but this time after driving for 45 mins. Power steering blew out of cap.....