Power-Steering Rehab - Junkyard Builder

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Car crafters love interchangeability, and there are very few GM parts that have remained basically the same from 1960 to 2009. The pump on the left is the newer, metric version with a press-on pulley, while the one on the right is the older, bolt-on version with a threaded shaft and a woodruff key. To disassemble the pump, the first step is to remove the pulley. Newer pumps require a specific power-steering pump puller/installer. You can buy a decent universal puller/installer from Summit Racing for a fair price.

Car crafters love interchangeability, and there are very few GM parts that have remained b

If you are a celebrity in America these days, it’s nearly a requirement to spend at least a week in some trendy, beach rehab facility. Thankfully, we’re not celebrities, but one of our junkyard power-steering pumps recently suffered from leak issues and cried out for rehab, so maybe we’re more tragically hip than we thought. With our minds now cleared from a synthetic power-steering-fluid-induced haze, we thought it might be interesting to show you how easy it is to put your classic GM Saginaw pump through rehab and have it come out a clean, happy, and fully functioning member of our high-performance society.

The Saginaw power-steering pump first made its appearance on GM cars in 1960. The early pumps used a threaded 5⁄8-inch-pulley-shaft-diameter fitted with a woodruff key. Later, GM changed to a larger, 3⁄4-inch shaft minus the threads and woodruff key, converting to a press-on pulley. According to RockAuto information, GM was still using this pump in some LS truck applications as late as 2009. The fittings and fasteners in later pumps merged to metric at some point but retained the same basic pump configuration, with its integral fluid reservoir. The ’65 and ’66 big-block Chevy applications used a smaller pump housing that relied on an external reservoir. If you like the idea of a separate reservoir, Original Parts Group (OPG) reproduces that pump cover. One thing that makes this pump so popular is that the same basic reseal kit will service all pumps between 1960 and 2009, and you can find one from RockAuto for less than $10.

After pressing off the pulley, remove both bolts on the back side of the reservoir and remove the large, high-pressure fitting from the rear of the pump. Then, mount the pump in a vise using the flat portion of the shaft housing. The housing is press-fitted over the pump, and a few whacks with a large rubber mallet will drive the reservoir off the pump body. This will expose the one large and three smaller O-ring seals (arrows) that need replacing.
After pressing off the pulley, remove both bolts on the back side of the reservoir and rem
There are two styles of high-pressure fittings: the SAE with an inverted flare (top photo) and the later metric version that requires Saginaw fittings (right photo). The good news is that these fittings are interchangeable in the pump housing, since the thread pitch between metric and SAE is close enough not to be an issue. We’ve tried this, and it works. This allows you to use a newer, metric pump but retain your original inverted-flare hoses (that’s a Saginaw fitting in the lower photo).
There are two styles of high-pressure fittings: the SAE with an inverted flare (top photo)
There are two styles of high-pressure fittings: the SAE with an inverted flare (top photo, left) and the later metric version that requires Saginaw fittings (top photo, right). The good news is that these fittings are interchangeable in the pump housing, since the thread pitch between metric and SAE is close enough not to be an issue. We’ve tried this, and it works. This allows you to use a newer, metric pump but retain your original inverted-flare hoses (that’s a Saginaw fitting in the lower photo).
There are two styles of high-pressure fittings: the SAE with an inverted flare (top photo,

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We mentioned that the Saginaw pump went metric at some point in the later ’70s, but we discovered that the thread pitch on the high-pressure output fitting that screws into the pump is so similar that the older SAE output fitting will screw right into the metric-pump body. This is important because the older pumps use inverted-flare fittings, while the newer ones use a Saginaw O-ring fitting. So if you want to update your ’60s GM pump with a newer ’90s Saginaw pump from the junkyard, the exchange is a snap. In most cases, even pump housings will interchange. If your pump housing is beat up, Tuff Stuff offers both natural and chrome housings that will fit most applications. So this means you could snatch a newer pump out of the junkyard, slip on your original pump housing (or a new one from Tuff Stuff), add new seals, and have a virtually new pump for very little coin. Plus, you can reuse your original pressure fitting to retain your original high-pressure hoses, so you don’t have to buy new hoses. There’s also a smaller, late-model power-steering pump called the Type II that we have some tricks for, but we’ll save for a later story.

Power-Steering Pump Bleeding

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If you remove the pressure-relief valve from the pump, you will see that behind it is a spring. Notice that the valve uses a small nut that retains a shim (arrow). The thickness of this shim determines the pump’s output pressure. When used with rack-and-pinion steering, these Saginaw pumps create too much pressure, making the rack feel twitchy. Borgeson makes a shim kit that increases the shim thickness, reducing peak pressure for use with rack-and-pinion steering.

If you remove the pressure-relief valve from the pump, you will see that behind it is a sp

If you also replaced the power-steering box, there is a simple bleeding operation you can perform that will eventually save you lots of time. Power steering is just like any other hydraulic system in that it will work best with no air in the fluid. So with a dry pump and box, fill the pump reservoir with fluid, and then with the front tires off the ground, manually turn the wheels lock to lock. This will force air out of the box and lines. Do this several times, and refill the pump with fluid as needed, until no more air bubbles appear in the reservoir. Now you can start the engine and slowly run the steering lock-to-lock. The system should not create any mechanical whine. If the system whines when running, there is still air in the system and you will have to wait 12 to 24 hours for that air to exit the system. You could also try applying vacuum to the system by drilling a hole and sealing a tube in a spare pump lid plumbed to a vacuum pump in order to draw the air out of the system.

Parts List
Description	PN	Source	Price
Gates seal kit	351160	RockAuto	$8.18
Dorman reservoir cap	82581	RockAuto	2.34
Royal Purple synthetic PS fluid	013626	Summit Racing	5.46
Borgeson flow valve-shim kit	899001	Summit Racing	16.97
PS cover for remote reservoir	CH28422	OPG	90.98
AFCO PS hose kit w/steel fittings	10637102	Speedway Motors	149.99
AFCO PS fluid	10636901	Speedway Motors	8.99
Power steering pulley tool, OTC	4530	Summit Racing	38.95
Tuff Stuff reservoir, left return tube	6501C	Summit Racing	39.95