HYDROBOOST FAILURE

What NHTSA is examining

Subject vehicles:caprice, caprice classic, custom cruiser, deville,electra, estate wagon, fleetwood, lesabre, ninety-eight, parisienne,park avenue.(all 1984-86 gm vehicles equipped with hydroboost ii systems)analysis:consumer complaints allege several problems involving the powersteering and power brake systems of these vehicles.these problemsinclude: power steering fluid loss, power brake fluid loss, leakage fromthe hydro-boost ii power brake booster, broken booster seals, and mastercylinder failure.all problems seem to be related to the hydro-boost iipower assist system, in which the working fluid provides power assist to boke booster.the effect of these problems could be a loss of steeringcontrol and/or brake effectiveness.status:the voluminous amount of data supplied by gm is presently being coded by a contractor and should be completed by 12/30/87. Gm data indicated a 50% weibull distribution failure at 50k miles for the piston push-rod seal. This pe looks to have an extrodinarily high frequency, although the severity apears to be low.should be interesting discussing this for upgrade/closure.===

Vehicles under investigation