There is no single, universal thread size for power steering pump pulleys. The mounting interface can be pressed on, use a central mounting bolt, or rely on a small set screw in the hub. If a thread is used, the size varies by manufacturer and model—common SAE bolt sizes such as 3/8-16 or 5/16-18 appear on many pumps, and metric variants like M8x1.25 or M6x1 are found on others. Always verify the exact specification from the vehicle’s service manual or the pump’s parts diagram.
The exact question depends on the particular pump design. This article outlines the main mounting approaches and how to determine the correct size for your specific vehicle, since there is no single answer that fits all pump models.
Mounting configurations for power steering pump pulleys
Power steering pumps attach to their shafts in several common ways. The method used determines whether a thread is involved and, if so, what size it might be.
- Press-on pulleys, often secured with a set screw or clip rather than a threaded bolt into the shaft.
- Bolt-on pulleys that use a central mounting bolt into the pump shaft, with thread size varying by model.
- Pulleys that attach to a separate hub or adapter with its own threads.
- Pulleys retained by a nut and collar rather than a through-bolt.
Knowing the mounting configuration helps narrow down whether you’ll encounter a threaded interface and, if so, which size to expect.
How to determine the correct thread size for your pump
To ensure you select the right hardware, use these steps to identify the exact thread size for your pump pulley.
- Identify the pump model and vehicle details (make, model, year) and locate the pump part number if possible.
- Consult the official service manual, workshop guide, or parts catalog for the pulley mounting hardware and its thread specification.
- Inspect the existing hardware: measure the bolt diameter with calipers and determine the thread pitch with a gauge, or compare to a known-good bolt.
- Match the measurement to a compatible fastener at an auto parts store or order the correct pulley kit for your pump model.
By confirming the exact pump model and hardware, you can source the correct threaded size (or confirm that no thread is required) and avoid cross-threading or installation issues.
Summary
The thread size on a power steering pump pulley is not standardized across all vehicles. Sizes and mounting methods vary by manufacturer and model, ranging from pressed-on pulleys with no thread to bolt-on designs using various SAE or metric thread specifications. Always verify with the vehicle’s documentation or measure the hardware to determine the correct size for your specific pump, and consult a qualified technician if you’re unsure.
What size are the fittings on a Saginaw power steering pump?
3/8"
Saginaw Power Steering pumps have a Female 3/8" Inverted Flare Fitting in the back of the pump while your factory Ford high pressure steering hoses have a male Hose end.
What size wrench do you need for a power steering pump pulley tool?
Use 5/8” and 13/16” or 16 and 21mm wrenches, or a 5/8” or 16mm socket with a ratchet or breaker bar, to turn the forcing screw until the pulley presses off the shaft.
What size thread is a power steering pump pulley?
3/8-16"
Threads are 3/8-16" to fit pulley shaft threads.
Are all power steering pump pulleys the same?
Each pump uses a unique pulley that does not interchange. Using a pulley from a different pump, almost always causes belt alignment issues.