Power Steering Hoses and Fittings: A Complete Guide
A leaking high-pressure power steering hose doesn't always mean buying a new line from end to end. Sometimes the flexible section has failed and the steel pipe either side is perfectly sound. Sometimes the whole line needs replacing. And if you're building something new, a braided AN6 line may suit the job better than an OE-style hose.
This guide covers how to decide, which hose to use, and how to identify the threads on your pump and rack, which is the part people most often get wrong.
Repair or replace?
Repair the line when the failure is confined to one place: the flexible hose has split or is weeping at a crimp, or a short length of the steel pipe has corroded while the rest of it is sound. The failed section is cut out and new hose is joined in, so you keep the original pipe and its routing.
Replace the line when the steel pipe is corroded along its length, when the end fittings themselves are damaged, or when you're changing the routing for an engine swap or a new build.
Not sure which you have? Send us photos of the line and both ends, and we'll help you work it out.
Repairing a power steering pipe with compression fittings
Our compression fittings join 3/8" high-pressure hose onto an existing rigid steel power steering pipe. They're made in three tube sizes:
Measure the outside diameter of the pipe with vernier calipers, not a tape measure. 3/8" is 9.53mm, close enough to 10mm that you can't tell them apart by eye, and the wrong one won't seal. 5/16" is 7.94mm.
Compression fittings are for power steering pipes only. We don't offer compression repairs for brake pipes.
3/8" OE-style or AN6 braided?
We build power steering lines in two systems.
| 3/8" OE-style, crimped | AN6 PTFE stainless braided | |
|---|---|---|
| Working pressure | 1,500 PSI (SAE J188 Class B, as marked on the hose) | 2,750 PSI maximum |
| Ends | Crimped, permanent | Reusable or swaged |
| Best for | Repairing or replacing a factory line so it fits and looks original | Engine swaps, track cars and new builds |
As a rule of thumb: matching an OE line, use 3/8". Building something new, use AN6.
Both are available as made-up lines or as parts: 3/8" high-pressure power steering hose and AN6 PTFE braided power steering hose. For more on AN6 sizing and fittings generally, see our AN-6 hose and fittings guide.
Identifying the threads: M14, M16 and M18
The power steering connections we're asked for most often are metric: M14, M16 and M18. The diameter alone isn't enough, though. You also need the pitch, the distance between threads.
Our M14, M16 and M18 adaptors are 1.5mm pitch, but M14 also turns up in 1.25mm pitch, and we stock banjo bolts in both. An M14 x 1.25 bolt will not go into an M14 x 1.5 port. A thread pitch gauge settles it in seconds; if you don't have one, send us the old fitting and we'll help you check it.
Then work out how the connection seals.
Banjo fittings
A banjo connection is a ring-shaped fitting held on by a hollow banjo bolt, with a copper sealing washer either side. We stock M14, M16 and M18 banjo adaptors to AN6, alloy banjo bolts in M14 x 1.25, M14 x 1.5, M16 x 1.5 and M18 x 1.5, and a steel M14 x 1.5 bolt.
Copper washers are single-use. Once crushed, they won't seal properly a second time, so fit new ones whenever the bolt comes out: 14mm, 16mm and 18mm.
Male O-ring tip adaptors
Where the port takes a male fitting that seals with an O-ring, our AN6 to M14 x 1.5, M16 x 1.5 and M18 x 1.5 O-ring tip adaptors convert it to AN6, in aluminium or steel.
Imperial threads: UNF and inverted flare
Some systems use imperial threads: 1/2"-20 and 5/8"-18 UNF swivel fittings, or inverted flare in 1/2"x20, 9/16"x18, 5/8"x18 and 11/16"x18. A 5/8"-18 UNF swivel and a 5/8"x18 inverted flare share a thread size but seal differently, so check the seat as well as the thread. If in doubt, send us a photo of the end and we'll help you identify it.
What we need from you
To build a line, we need four things:
- Length, end to end including the fittings. If you're unsure, send the old hose or a photo with a tape measure alongside it.
- Fitting type and angle at each end: straight, 45° or 90°, and whether it's a banjo, a female swivel or a male thread.
- Thread size and pitch at the pump, rack or pipe the line connects to.
- Reusable or swaged ends if you're going AN6.
For a repair, add the outside diameter of the steel pipe.
Parts if you're building it yourself
Everything is sold individually in our Power Steering Hose & Fittings collection:
- 3/8" OE-style: hose by the millimetre, plus crimp fittings including a 14mm banjo, M16 90° male, AN6 female (straight, 45° and 90°), and 5/8"-18 and 1/2"-20 UNF male and female swivels
- AN6 braided: PTFE hose by the metre, swaged female ends (straight, 45° and 90°), and adaptors to M14, M16 and M18
- Repairs: 3/8", 10mm and 5/16" compression fittings
- Consumables: banjo bolts and copper washers
How to order a made-up line
Email sales@brtmotorsport.co.uk or use our contact page with the lengths, fittings and threads, or photos if you're unsure. We'll confirm the specification and price before anything is made. Most orders are made up the same or the next working day and posted anywhere in the UK.
More on what we make: Custom Hose Building.