GM Loss of power steering

The Center for Auto Safety is the nation’s premier independent, member driven, non-profit consumer advocacy organization dedicated to improving vehicle safety, quality, and fuel economy on behalf of all drivers, passengers, and pedestrians.


Sixteen million 1980-88 front-wheel-drive GM cars (listed below) are
prone to loss of power assist for the rack and pinion steering assembly.
Usually, this loss of assist first occurs only when the engine is cold,
but in time it becomes more noticeable after the car has warmed up. The
defect typically shows up after the warranty expires and costs $300-800
to fix. The Center for Auto Safety (CAS) has received well over 25,000
power steering complaints from owners of GM vehicles. Our surveys indicate
a failure rate as high as 50%.

In 1986 and 1989, CAS petitioned the National Highway Traffic Safety
Administration (NHTSA) to investigate loss of power steering on these
GM cars and order a recall. CAS also wrote the Federal Trade Commission
(FTC) about GM’s “secret warranty” covering repair costs after the written
warranty expired. NHTSA twice opened a safety investigation, but never
ordered a recall despite reports of hundreds of accidents and at least
three deaths when the steering locked on these cars. The FTC refused to
take action on GM’s secret warranty, and GM fights any recall by claiming
loss of power steering is not dangerous.

The defect involves a notched cylinder called a “spool valve” that controls
direction of power steering fluid that has been pressurized by the power
steering pump, and the teflon rings on which the valve rotates. The spool
valve operates inside another cylinder (either aluminum or cast-iron)
that forms part of the rack and pinion housing assembly. When the driver
turns the steering wheel, for example, to the left, the spool valve rotates
with respect to the housing, uncovering passages that allow pressurized
fluid to push on the “left” side of a piston connected to the steering
rack. This fluid pressure “assists” the driver’s input from turning the
steering wheel in that direction. Turning the steering wheel further to
the left increases the volume of fluid pushing on that side of the piston.
When the driver turns the wheel to the right, the spool valve directs
fluid to the other side of the piston. Returning the wheel to center neutralizes
pressure on both sides of the piston. The spool valve rotates only if
the wheels resist being turned, as in low speed turning maneuvers; it
proportions out the correct amount fluid to overcome this resistance.

In these GM power steering units, teflon rings encircle the spool valve;
the rings must maintain an effective seal against the housing to prevent
fluid from bypassing the valve and causing fluid build-up on the “wrong”
side of the piston. As the rings age, their ability to seal worsens. The
rings also dig grooves into the soft walls of the aluminum rack-and-pinion
housings GM used on 1980-88 cars. Fluid then bypasses the rings and builds
up pressure on both sides of the piston, increasing the effort needed
to turn the steering wheel in either direction. Initially, the rings fail
only when the engine is cold; their seal against the housing improves
once steering components warm up from the heat of engine operation. Ultimately,
the rotation of the rings deepens the grooves in the aluminum housing,
and the rings fail to seal even after warm-up. One way to avoid the seal
problem is to substitute a cast-iron housing for the aluminum one; GM
finally did this on 1989 models.

This loss of power assist is a design defect, one that GM has attempted
to resolve by issuing new parts. A June 1984 GM service bulletin (Buick
84-3-3A; other divisions issued same bulletin) described a mid-1984 design
change in which the housing valve bore “will have a textured finish to
further ensure valve ring retention to the bore.” The same bulletin described
another mid-1984 design change to prevent loss of power assist due to
fluid leaking “past the rack piston ring in the housing tube bore.” Unfortunately,
none of these remedies seemed to work for very long.

GM notified only the owners of 1980-81 X-cars that it would pay for p/s
repairs through 5 years/50,000 miles. GM issued press releases on January
21, 1988 and May 25, 1989 admitting it extended the warranty on power
steering to 5 years/50,000 miles, but in both cases GM refused to notify
owners directly. Because of GM’s secrecy, many consumers never learned
of the extensions or learned about them too late, and as a result paid
needlessly for power steering repairs. When consumers complained loudly,
GM often reimbursed them for part or all of repair cost, even on vehicles
past the 5/50,000 limits. _____________________________________________________________________
A-cars: Century, Celebrity, Ciera, 6000 (1982-88).
C-cars: Electra/Park Avenue, DeVille/Fleetwood, 98/Regency (1985-88).
E-cars: Riviera, Eldorado/Seville, Toronado (1986-88).
H-cars: LeSabre, Delta/88, Bonneville (1986-88).
J-cars: Skyhawk, Cimarron, Cavalier, Firenza, 2000/Sunbird (1982-88).
L-cars: Beretta/Corsica (1988).
N-cars: Somerset/Skylark, Calais, Grand Am (1985-88).
V-cars: Allante (1987-88).
X-cars: Skylark, Citation, Omega, Phoenix (1980-85).