How to repair a leaking Hydro-boost unit

Discover how to effectively repair a leaking Hydro-boost unit in this comprehensive tutorial. This video demonstrates that you can fix the issue for a fraction of the cost of a new unit, and the repair can typically be completed in an hour or less. Best of all, you won’t need to remove the entire unit from your vehicle, making this a convenient solution for car owners. Watch now to learn the essential techniques for a successful repair.

[@lakeviewgarage3103]

Great video on repairing the leaky hydroboost. Thanks for making it so we can help keep our older rigs alive.

[@BruceCoggins]

Thank you...yes it is an easy process and saves you a lot of time and money.

[@ronsmith7527]

Yours is definitely the best video on this. I don’t understand how we avoid rolling the lip of the new seal since the whole assembly goes on over the cylinder and it’s not tapered. Apparently it’s not a problem since no one has mentioned it.

[@BruceCoggins]

Thank you and you bring up a good point...I've often thought about that when rebuilding these but never had it happen. I always oil up the seal so maybe that's why it seems to slip on there.

[@noonergarage4114]

Thanks for the tips and video. Worked great for my 1993 GMC dually. 🙂

[@jamesmills4175]

very nice looking truck.

[@BruceCoggins]

Thanks 👍

[@kennysmith6824]

Great video, my hydro boost seems to be leaking the most from the accumulator. That kit you used doesn't show an O-ring for it so I'll have to look around more on Amazon.

[@BruceCoggins]

@@kennysmith6824 you should be able to match up the old O-ring at your local auto parts store. The accumulator is fairly easy to remove....a large C clamp and a pick to remove the retainer will work just fine. When you remove it, make sure the piston is at the top and not bottomed out. If it's bottomed out, you will need to replace the accumulator.

[@kennysmith6824]

Thanks, The accumulator is wobbly loose without pulling it off yet. It spins freely too. More that likely it is bad but the brakes and PS work fine. I'll pull it apart and check its condition.

[@BruceCoggins]

@@kennysmith6824 yeah, keep me posted and let me know what you find. If you need a new accumulator, I found mine on eBay. They are supposed to be pressurized with something like 350 to 400 psi of nitrogen.

[@kennysmith6824]

​​@@BruceCoggins I got it off today without pulling the unit off the truck. The plunger is weak and does push down. The only ebay unit I found was for a GM 6.2L. I'll probably just put a better o-ring on it and send it. The leak got worse after moving it around yesterday. Too bad these aren't easier to find. Every place just wants to sell you the remanufactured unit that are hit or miss.

[@BruceCoggins]

Check these guys out and see if they have an accumulator for your application...www.powerbrakeservice.net/hyacshgo.html

[@jeffmunger]

Thank you for the video. Going to be doing this soon. Your neighborhood has almost as many dogs as mine :)😂

[@BruceCoggins]

LoL, thanks. I think my neighbors bought a new dog for each of their kids and they like to walk them around my cul de sac about once a week... annoying LoL

[@65mrcarguy]

Good video. Beautiful truck!

[@BruceCoggins]

Thanks 👍

[@elliottmeeker4534]

If replacing power steering pump and bleeding that remember to bleed the hydroboost brakes

[@chrismadaj8751]

Nice should could've seen this first GODSPEED

[@papergatorzfedducca7998]

Do you think the master cylinder will cause all 4 brakes to slightly drag? I can release each one when I open the bleeder screw. Once I drive it for about 3-7 minutes it starts back dragging. I say slightly dragging because I can jack up the truck and turn them by hand with a lot of force. No leaks on the master cylinder or hydro boost. I’ve greased slider pins, bleeding the brakes 3 times, topped off the fluid on both power steering and brake fluid. Power steering is making the whining noise. It’s a 2004 Suburban with hydro boost system. Please help.

[@BruceCoggins]

Disc brakes do have a tendency to slightly drag but the wheels should turn freely when you spin them by hand. One thing you can try is loosen the nuts holding the master cylinder on the booster and see if you can feel the rod pushing it away...if it does then the rod is too long or the pedal isn't returning all the way. It shouldn't cause all 4 wheels to drag because as you push the brake pedal the fronts activate first and then the rears.. or vice versa but either way only one or the other will be in play. As far as the whining noise in the power steering, as soon as the bubbles disappear the noise should go away. Check the ps fluid with the engine running and add as necessary.

[@papergatorzfedducca7998]

@@BruceCoggins ok thank you I’ll let you know how it goes tomorrow!!!🔥🔥🔥

[@papergatorzfedducca7998]

@@BruceCogginsnew subscriber 🔥🔥🔥

[@Hallnout]

Did you figure out what your problem was then?

[@papergatorzfedducca7998]

@@Hallnout master cylinder.

[@shep145]

The seals are notoriously hit and miss in quality. I used the Amazon ones but it still leaks so I get to do this twice. :)

[@BruceCoggins]

Exactly, the seals you get today aren't as good as they used to be. One trick that works is to pack the seal with grease before you install it. That's something we use to do years ago. Try that and see how it works for you.

[@XroorX]

What is The 350psi cylinder called? On my 2006 it has “BAS” something g on it. Thanks

[@BruceCoggins]

It's an accumulator. Once you separate the two halves it is easy to compress the accumulator with a large C-clamp so you can remove the c-clip holding it in. There is an O-ring on the outside so just replace that. Do not try to compress the piston to get it apart. If the piston is collapsed then you should be able to order a replacement from eBay.

[@XroorX]

@@BruceCoggins thank you so much for the reply. Bought the truck with only the REAR lines replaced, then had mechanic replace the fronts….then, he only tries to bleed the fronts…. So I paid him and he split. Now, the cylinder is making a slight goose sound when I depress the brake…engine is mint, interior is mint, now I’m understanding why guy only wanted $2k

[@danholso3482]

Got a weird situation with my '96 2500, the tag in the glove box shows a JD7 but the parts stores all said that it's supposed to be a JB8 hydro boost. Rather than figuring out which, does the kit fit both? And how do I know which kit? The parts stores don't have them...?

[@BruceCoggins]

I've repaired lots of hydro boost units and every one I've seen takes that figure 8 gasket and one of the seals....the kits I order come with the figure 8 gasket and 2 seals...one larger and one smaller. I don't see why one of these won't work in your situation. I'd pull it apart and see what seal it has and then order a kit from Amazon

[@youmarcop]

I would know what part was booster leaking? My problem is between booster and master cylinder

[@BruceCoggins]

Once you pull it apart you will see the figure 8 gasket and then there is a seal in the bore...I show this in the video. Replace those two things and reassemble

[@tanakahege3551]

What did do wrong, my breaks are locking up

[@BruceCoggins]

There are a few possibilities...the rod behind the master could be installed wrong and it is activating the master at rest.To check this, loosen the master and see if it pushes away from the mounting area. Are the front brakes locking up or the rear?

[@tanakahege3551]

@@BruceCoggins front Brakes.. thank you kindly for your response.. I will work on it again over the weekend.. the pedal goes down a notch when start the truck up and based on your response I totally agree

[@tanakahege3551]

@@BruceCoggins the rod you are talking about is it the one with the spring or the one you have to line up from the inside

[@javierzapata92]

Do you have a part number

[@BruceCoggins]

Here is a link to one on Amazon...www.amazon.com/dp/B07KFQ4YJJ/?coliid=I1S6DNBJALUZ96&colid=1087UX0Y8RZ9M&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

[@busher69]

Good video but with today's trucks engine bay being stuffed with horse hockey, I'm taking the assembly off except for the master cylinder.