Latest Revision: 07JN2002
CORVETTE C2 AND C3 POWER STEERING PUMP PART AVAILABILITY
The C2and C3 Corvette models are now 20 to 40 years old. All Corvettes with power
steering from 1963 through 1982 used the Saginaw P-series “big” power steering pump.
This paper has been written to assist in rebuilding and/or replacing your power steering
pump. In order to aid in understanding the procedures that are being described it is
recommended that you download additional pictures and text that has been scanned and
posted at the www.corvettefaq.com websight. Additional pages that you can download are
as follows:
P-PumpFlowControlValve.doc
P-PumpLeakPoints.doc
P-PumpBlowUp.doc
P-PumpBenchRepair.doc pages 1,2,3,&4
The exact replacement power steering pump that was used on your Vette is no longer
available from General Motors. However, the full power steering pump assembly, or the
pump alone, or the correct reservoir alone can be obtained through a number of Corvette
suppliers. Prices range from $375 for a NOS 1975 –79 pump assembly to $145 for a
1965 –74 rebuilt pump assembly. Seal kits are also available for around $12.
There is also a source for rebuilding your power steering pump that may just require a
trip to your local salvage yard. There are millions of the Saginaw P-series power steering
pumps that were used in other General Motors vehicles and utilize many common parts
with the Corvette pump. The pumps used in the Chevrolet and GMC C/K trucks and also
in the new lines of GM light duty pickups and SUV vehicles are an excellent source of
parts. These are the trucks with Chevrolet 4.3L V6, small block, or big block V8s.
These pickup and SUV pumps have internal displacements roughly the same as your
Corvette pump. However, the pressure relief settings in these truck pumps are in the
1500 psi range. The setting in your Corvette pump is only around 1000 psi. Now, the
flow control valve in the pump also controls the pressure relief setting (Reference:
P-PumpFlowControlValve.doc.) Therefore, it is very important that you switch the flow
control valve from your Corvette pump into the truck pump so that the pressure relief will
be correct. You need to do this because the seals in the control valve and also the
pressure hoses used in the Corvette steering system were only designed for 1000 psi
pressures.
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The “big” Saginaw P-series power steering pump was first used on the 1963 Corvette and
its use continued through the 1982 model year. One of the things that makes a power
steering pump unique is the fluid reservoir. All P-series pumps have the reservoir sealed
with a large diameter o-ring that fits into a cavity on the flange of the P-pump housing.
The reservoir is retained by two studs/bolts and the large hexagonal discharge fitting, all
three located on the back side of the pump. One marvel of interchangeability, all
reservoirs from 1963 to the current model year will interchange from one P-pump to
another. Reference: P-PumpBlowUp.doc
The Salvage Yard Approach
If you decide to go the salvage yard route to obtain replacement parts, the good news is
that there were literally millions of 1960’s through current model GM light duty pickup
type vehicles that were produced with P-series power steering pumps that can donate
parts for your Corvette.
Note: This paper assumes that you are familiar with the Saginaw power steering pump
and/or are using the Chevrolet Overhaul Manual or some other appropriate reference
when performing the procedures referred to in this paper. You can also download the
following instructions: P-PumpBenchRepair.doc pages 1,2,3,&4
What to Look For
There are several design factors that you need to be aware of when you go out searching
for a power steering pump replacement. Here are the basic changes that occurred through
the years that can affect your search for replacement parts.
Integral Steering Fluid Reservoir
Through 1974 the Corvette used a design that had the top portion of the reservoir and the
fill neck brazed to the main body of the reservoir. Starting with the 1975 model year,
what was called the “ham can” reservoir was used from that point forward. The top
portion of the reservoir was all one piece and only the fill neck was brazed in place. It is
my belief that either reservoir will function correctly on any of your Corvette models, but
for correctness, 1975 is the breakpoint from the one design to the other. Either of these
reservoirs will fit on a new pump.
Driveshaft Pulley Installation
Before the 1975 model year, all General Motors power steering pump pulley connections
used a 9/16-18 UNF nut, a driveshaft with a male thread and keyway, and a 1/8x1/2
woodruff key. Starting in 1975, a new design interference fit pulley attachment was
introduced on all GM power steering pumps. You cannot interchange pulleys or pumps
with one connection to the other. The visual pump driveshaft differences make this
change very easy to identify.
Conventional Fasteners versus Metric
Before the 1980 model year, all external connections to the power steering pump were
conventional threads and fittings. Starting in 1980, all General Motors power steering
pumps were converted to metric fasteners. This means that all external connecting parts
were now metric.
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Metric Stud and Union Reservoir Seals
One other thing, with the conversion to metric fasteners the depth of the stud and union
seal cavities in the metric pump housing were deepened. These were the cavities under
the heads of the two studs and the pump union. The deeper cavities required thicker
square cut seals to properly fill the cavities. Reference: P-PumpBlowUp.doc, #5 Seal
“o” ring (Housing) and #19 seal “o” ring (Housing to Stud). Don’t use the old
conventional square cut seals in the metric pump housing, they will most likely leak.
The conventional to metric changes included the following:
The discharge fitting on the back of the pump.
Conventional Attachment - 5/8-18 UNF female thread and 45 degree brass flare seat.
Metric Attachment – M16x1.5 female thread with a o-ring port.
You must use the pressure hose assembly with the correct end configuration to fit the
appropriate port. Reference: P-PumpLeakPoints.jpg
NOTE! There is an inexpensive aluminum insert that can be purchased and pressed
into a 16x1.5mm o-ring pump discharge port. The insert has a 45 degree flare face
and essentially makes a mating surface for your old hose as it connects into the more
modern pump port. This insert then allows a power steering pressure hose with a
conventional 5/8-18, 45 degree flare end to screw into the metric port and seal
properly. (You will find that a 5/8-18 UNF male fitting will screw very easily into a
16x1.5mm female port.) The insert is available from:
Lee Manufacturing
11661 Pendelton St.
Sun Valley, CA 91352
818-768-0371 (talk to Tom Lee or his wife)
The four tapped mounting holes on the front of the pump (right behind the
pulley). Most pump attachment brackets use one or two of the four tapped holes.
Conventional Attachment – 3/8-16 UNC tapped holes.
Metric Attachment – M10x1.5 tapped holes
The two studs on the back of the pump that retain the reservoir and mount the
pump.
Conventional Attachment - 3/8-16 UNC thread into pump housing and the threaded
stud. GM #5689546 Stud
Metric Attachment - M10x1.5 thread into pump housing and the threaded stud.
GM #7831388 Stud
Note #1 It is best to keep the same vanes, cam ring, and the rotor & driveshaft together
as a set from each pump. If possible, do not disassemble the rotor from the driveshaft.
After you remove the pulley check the area between the pump pulley and the pump
housing seal. If it is corroded, polish that area with crocus cloth before attempting to pull
the driveshaft and rotor back through the pump housing.
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Note #2 If you find that you must separate the rotor from the driveshaft, use the same
retainer clip or ring that came with the driveshaft. The early pumps used a clip with a
square cut groove in the driveshaft. Starting in 1981, a round wire ring with a rounded
groove in the driveshaft was used from then on. The correct retaining device must be
used with the appropriate retaining groove.
Note #3 If your pump was leaking at the driveshaft seal and you remove the driveshaft
from the pump, now check the surface finish on the driveshaft right under the seal lip
area. If it is pitted and corroded or there are grooves in the metal, you must attempt to
clean the area by polishing with crocus cloth. If minor surface irregularities cannot be
cleaned in this manner, you will have to replace the driveshaft.
Note #4 I strongly recommend refilling your power steering system with genuine GM
power steering fluid. There are fluids that are labeled power steering fluid, but the only
one used by General Motors as original factory fill is the one I recommend. The amber
colored fluid, available from any GM dealer was specifically formulated to work in the
Saginaw power steering pump. For maximum durability use GM steering fluid (GM
#1050017 32oz).
Specific Exchange Examples
1). Your original pump on your Corvette was made before the 1975 model year:
a). Your replacement pump was also made before 1975:
All parts will interchange between these pumps. Use your original reservoir, flow
control valve, spring, union, and studs.
b). Your replacement pump was made between 1976 and 1979:
All parts except the driveshaft will interchange. You will need to use your
original driveshaft and pulley with the replacement pump.
c). Your replacement pump was manufactured 1980 or later:
First make sure you get the metric fasteners that attach the front of the pump to
the engine brackets. Now check to see if the pump has two metric studs on the
back side. These metric studs not only have metric threads where they attach into
the pump housing, they also have metric threads where they stick out and attach
to your engine brackets. Your original pump had two studs so you need two
metric studs on your replacement pump. If you require additional metric studs
they are available from your local dealer, or from a Corvette supplier. You will
also need two metric nuts to fit the studs. You should use your original reservoir,
flow control valve, spring, and union fitting.
2). Your original pump on your Corvette was made between 1975 and 1979:
a). Your replacement pump was made before 1975:
In order to use your original interference fit pulley, you will need to use the
driveshaft from your pump. Be sure to use the reservoir, flow control valve,
pump union fitting, and spring from your original pump.
b). Your replacement pump was also made between 1975 and 1979:
All parts will interchange. You should use your original reservoir, flow control
valve, spring, and union fitting.
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c). Your replacement pump was made 1980 or later:
Same as 1). c). above.
3). Your original pump on your Corvette was manufactured 1980 or later:
Your best bet is to find a pump built 1980 or later with metric fasteners and the
interference fit pulley attachment. Use your original flow control valve, spring,
union fitting, and reservoir.
For the most part, the Saginaw P-series power steering pump is a marvel of design
longevity. The basic housing, rotating group (rotor, vanes, and cam ring), pressure and
thrust plates have been carried over with only minor refinements through the last 40
years. The other good thing is that Saginaw did a great job of standardizing as many of
the pump components as possible. When pump design changes occurred, for the most
part, they were introduced throughout all General Motors vehicles at the same time.
A Parting Word
I have (to the best of my ability) gathered the following information from engineering
drawings and by speaking to people that worked on the power steering pumps used in the
C3 Corvette. Please be aware, a lot of this information is well over 30 years old. Also,
you should always follow procedures and instructions provided from shop manuals and
other reliable sources when assembling and disassembling the power steering pump.
One last bit of information: If a part to be available through GM dealers, then it is
generally also available through numerous Corvette suppliers. You can shop around for
the best prices.
A Word About Service Part Pricing
General Motors power steering pumps have many common parts that are interchangeable
between various makes and models. If you purchase a part from a General Motors dealer
you should not be paying a premium for a Corvette part that is common with other GM
vehicles.
A Final Parting Word
Please don’t go running for a lawyer to sue my butt if you purchase a cheap donor pump
and something doesn’t work exactly as I describe. In fact, if you have a problem, do
other Corvette owners a favor and be sure to get back with me so I can update the
information and keep it as accurate as possible.
Also, if you have a favorite supplier that has access to power steering pump parts or
complete assemblies and would be a good source to help other Corvette enthusiasts, feel
free to share this information. I will be happy to include additional names of suppliers in
my Reference List that follows. Contact me at: JIML82@aol.com.
Jim Shea
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References:
Zip Products
Order Line: (800) 962-9632
On Line Store: www.zip-corvette.com
Paragon
Order Line: (800) 882-4688
On Line: www.corvette-paragon.com
RIK’S Unlimited
Order Line: (888) 745-7838
Tech Info: (828) 433-6506
On Line: www.riksvet.com
Dr. Rebuild
Orders Only: (800) 866-9362
Tech Info: (203) 366-1332
Websight: www.docrebuild.com
GM Parts Direct (Flow Chevrolet)
Order Parts Websight: www.gmpartsdirect.com
Tech Info Email: gmpartsdirect@flowauto.com
PumpPartsR&R07JN2002
JIML82@aol.com
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