Hello everyone. I have an ‘08 that is leaking fluid around the brake pedal. I was thinking that it was power steering fluid from the hydro boost like I had dealt with on my ‘03, but when I was looking to see if they had similar boosters I see that in ‘08 they changed the master, booster, and ABS to a “single” unit that looks very much like the H3 brake unit. Does anyone know if the unit can be rebuilt? Or swapped for the H3 unit? I see there is a new unit for about $900 but I just wanted to see if anyone else worked on one of these before I tore into it. Thanks

 

rock auto has the complete unit for 808$ if that helps. they also sell some individual parts and seals for it but not the main body from what i saw.

 

Just an update. I pulled the master. And got it apart. The unit is almost identical to the H3 unit but it isn’t the same. I only found one master cylinder replacement on eBay for $720, but it requires a “master cylinder rebuild kit” to attach the ABS unit and booster to the master which is another $130. I have all the o-rings out and am trying to see if I can match them up at the local brake shop, but it’s looking like the whole unit will be replaced, and then to the dealer for abs programming. The 2003-2007 was so much simpler, but when you drive a 08-09 it like driving a luxury car over the first gen. I’ll post another update when finished.

 

Did you ever get it all finished? There's 2 of us here having the same problem now...

 

Hi guys I got sidetracked and never finished the thread. I went to a few brake shops, the biggest shop around here is capitol brake and clutch. They said they could find no rebuild kit and couldn’t help me with finding orings. I bought the unit online and replaced it. It did not require programming to get it going it ran right out of the box. If anybody finds a rebuild kit let me know. I would love to have a backup. Thanks.

 

So I replaced the booster assembly back in 2020 or maybe the beginning of 2021 I don’t really remember it’s now 8/2025. But I was vacuuming this morning and again saw leakage coming from the replacement booster. The booster was brand new GM when I got it. I am super disappointed as there are no replacement parts and the GM parts are bad quality. Has anybody swapped the 08-09 booster assembly for the older hydroboost setup?

 

Please let me know if you figure out how to do this. and have the computers be happy with no lights. I suppose its possible because the escalade of the same year is a hydroboost/abs pump setup.

I am also very dissatisfied with this setup. Brake response time is terrible, pedal feel is inconsistent and lacks feedback. Honestly atrocious to drive especially when making precision maneuvers offroad.

Once my second unit goes out I'll get a hydroboost system to work and post a thread.

 

if it is leaking into the cabin the issue would most likely be with the master cylinder seals not the whole unit.. if you can mesure the bore and seals you might be able to replace just that. as long as the bore is not rusted as that would damage the new seals. you would have to use a brake cylinder hone to clean it up. but if there is pitting on the inside walls it might also still leak since the oil might make it past those spots. in your case i dont think it would be pitted since it was new. but if its been on a shelf for 15 years (new old stock) the rubbers might have hardened.

 

These unit have now literally become impossible to find. I have not seen one pop up on a search for well for 2 years now. What ever was out there have been snatched up by specialty companies. Retrofitting back to the pre-08 hydroboost units looks like an almost impossible feat because of the integration into the vehicle systems, ie stability and roll control, ABS, the 4wd system and more. And since there were so few 08/09 I don't expect anyone in the aftermarket will come to the rescue.

I do know I have seen just the master cylinder part of the assembly pop up from time to time but don't know how successful someone would be trying to replace just that part.

This is one of those items that's going to be a real issue for us 08/09 owners unless someone come up with a solution!

 

While rather pricy Sweeting Performance still has them

https://www.powerbrakeservice.net/08huh2absbrm.html
https://www.powerbrakeservice.net/20and20huh2e.html

Found this also but not sure about the service, may have to contact them and see what they offer
https://www.fiverautoparts.com/parts...2008-2010.html

There are still some master cylinders out there at GM parts sites
https://www.gmpartsgiant.com/parts/g...tra2=&filter=()

Neal