Would you believe there's a magazine called *Brake and Front End*?.
Guess what's highlighted in the Mar 05 issue?.
Yep, the Hydroboost system.
Starting on Pg 42, the explain the basics of how they work, and some of the failure modes, diagnostics, and maintance.
Just to quote some of the highlights:
Under failure modes,
Noise Problems
Slow or incomplete return of the brake pedal
Over sensitive brakes
Self Applying Brakes
If fluid pressure is lost you have 1 application with 70% assist,
the second 30-40%
and the third 10%
These numbers are approximates.
Under Pedal Feel, it notes that the pedal will feel different then that of a vacuum boosted car.
Under service, it says they are not serviceable in the field. If the unit is not working properly it must be replaced.
And they mention to be sure to periodically flush the system, and purge the accumulator in the process.
IMO:
While they are in use by oems, excuse me if I'm not impressed with a failure mode that includes, *Self Applying Brakes*.
Not to mention having a problem and having to park the car. Most Parts houses have G-Body master cylinders in stock, and so far I don't recall not seeing at least one G-Body at any recycling center so if not overnight, a cruise to the local Recycling center and you could score a booster, if needed.
Not to mention that if you wind up relying on the higher assist possible with a HB, then if it fails, you'll be in a worse situation then even using a PM.