It appears I have a leak that has developed between the Hydroboost unit and the master cylinder. Looking on the web it seems its a popular problem with units with lots of mileage or age and the problem is usually a simple lip seal in the front of the unit where it connects to the master cylinder. Other then the leak the unit works fine and I think I am just asking for trouble replacing the unit with a rebuilt one.

Has anyone here removed one from their H2 ? I saw two flavors of doing the job. They are either completed removed from the vehicle unbolting them from inside the cab or moving the master cylinder forward and splitting the unit then replacing the lip seal in the removed assembly. I imagine it will be easier to do the repair on the bench (considering all the springs inside the 2 halves) but getting to the nuts inside the cab seems like a real pain.

Comments, suggestions?

 

I just went thru all of this. Save yourself headache and buy a new unit. I rebuilt mine, it lasted a week, purchased a rebuilt one lasted a week.

Its not a hard job at all:

Remove bother power steering lines.
Remove 2 nuts holding master cylinder to booster

Inside remove 4 bolts holding booster to fire wall, upper left is a bitch
Remove brake rod retaining clip and brake light connector.

Done

Tim

 

Hey Tim,

Thanks for the reply, I assume yours was leaking at the same place. What happened on the rebuild? did it just fail again or did the leak never stop? Where did you purchase the rebuilt unit from? I have read so many horror stories about many who have replaced their leaking unit with a rebuilt one just to have it fail (usually not for a leak) within a few months. I am afraid these things are much like steering boxes, sometimes you get a good one but usually the rebuilders do a crappy job.

 

I had a minor leak at the hydro boost inside the cabin and outside. I used AT-205 re-seal about 2 ounces worth in the power steering fluid its been holding fine since January cured both my power steering pump weep and the hydro boost. I also added to my engine oil and transmission it sealed up many of my H2 Leakes I bought a couple bottles. the engine took a whole bottle on its own.
Do Not use it in your brake fluid it is not made for the brake system.

 

Similar products have been around for many years! The product swells the seals temporary, and eventually those seals will fail completely. Just like a can of "fix a flat": Temporary use only"

 

I have never seen snake oil work until this one. in the cae of my old 2000 Toyota solar it sealed my rack and pinion for going on 12 years and that one was pretty bad it never leaked again not even a swet of oil. so I tried it on my H2 that was marking its territory when it got home and like I stated it worked for me so far since January. no **** marks on my driveway. sure replacing the part is what people want. but if the issues is seals and this stuff can help me stop it I will try it I have nothing to lose but the price of the sealer. if it lasts over a year or more then its paid for itself 100 folds I don't know what tomorrow will bring. I might get sideswiped parking the damn truck then what lost the truck and the new part. i already experienced that in December with the last truck. new plugs new motor mounts new coil packs and 4 new tires all lost had to start again with this hummer.
since you like Eric the car guy you might like this one

 

Yes same place for the leak.

I thought the rebuild went well. I had no issues, replaced every seal, etc. I also replaced the power steeering pump at the same time so it could have even been due to increased pressure. There must have been some wear within the bore that I did not see. The rebuilt unit came from Autozone but the new unit I got right from GM. My after thoughts were that there is so much riding on my trucks brakes, why get cheap?

Don't get me started on steering boxes.......I think I'm on #4 or #5.

Tim

 

Tim,
Good info, I went ahead and order a brand new and not rebuilt AC/Delco unit from Jegs today, on sale for $439 (if you can call that a sale). I checked with a number of places and the going rate for a rebuild (by a so called quality rebuilder) was around $200.00 and my core. OReily's and Autozone offer lifetime warranties with their units but I only want to do this one time.

I pulled my old unit today and it was clean inside and out. The bore lip seal looked ok but fit somewhat loose around the piston.

One of the things I did when I purchased this SUT is go from front to back and changed all the fluids. I may have shot myself in the foot with the power steering, perhaps it already had a can of the seal conditioner put in and going back to the original GM stuff caused the problem. I also ordered a seal kit and will replace the lip seal when it comes in, reassemble the unit and shelve it as a spare or if someone needs a genuine H2 Hydroboost.

Hopefully I will get the new unit (unmolested and not a repack) install it and be on my way never to look back at another hydroboost unit. After all as you say there is so much riding on my brakes, Very True,

 

Update: Crash and burn, Jegs had our hydroboost units on sale with 2 day shipping advertised. I ordered one last week and as of today the damn thing was still on backorder. Alias, Plan B, replace the bad seal in my old unit.

Couple of things: The AC/Delco Part number for a new unit for our H2's is: 178-0700, this has since been replaced with 178-1029 (this is the part you should now order)

Either way neither of these parts are available from the AC/Delco warehouse. Well, my seal I ordered for my unit that I was going to be used as a spare came in today. I figured it made more sense to try to fix mine rather then get some lame rebuilt unit from the autoparts store .I installed the new seals it and put the unit back into the vehicle and after completing the fill procedure I tested the vehicle, so far so good (knock on wood), dry as a bone and the brakes work fine.

I would like to note the new seal was larger then the old seal. Its almost as if the old seal had shrunk. This really make me wonder if someone in the past had put a conditioner/sealer in this unit and I caused the problem by flushing and installing the original GM fluid. It will be interesting to see how well it lasts or if the PS pump or steering gear box begins to leak. I guess we shall see.

For what its worth the replacement job looks much worse then it actually was. If you have some reasonable mechanics tools the most difficult part of the job is getting under the dash to remove the nuts that hold the hydroboost unit to the firewall.

Removing the master cylinder from the hydroboost is simply two nuts. It pulls forward easily and out of the way allowing the removal of the hydroboost unit. If you decide to do a seal replacement place break loose the bolts that hold the 2 halves together. Now place the unit in a shop vice using the bolts that the hydroboost to the master cylinder in the vice with the brake rod facing up. Now remove the bolts holding the 2 halves together. Its spring loaded so be careful. Lift the rear part of the assembly up being careful not to loose any of the spings or parts. Replace the lip seal in the cylinder (lots of youtube videos will show you how) replace the lip seal, and the halves seals and re-assemble the unit.

If your leak was between the master cylinder and the hydroboost this should correct the issue and you will have saved a bunch of money. True, this is probably not as good as a brand new unit but it gets my H2 back in action. In my case my hydroboost unit was in really clean condition. The piston was in excellent condition and the bore was clean. I am hoping this is a lasting fix. We shall see.

 

that's awesome I am glad you where able to fix it. do you have a part number or link for the seal pack you used?