Hynautic KS-17 Seastar Seal Kit for K3-K4 and PSK11-12

Hynautic KS-17 - Seal Kit for K-3, K-4 and PSK11-12 Cylinders

KS-17 is a genuine Hynautic cylinder seal kit commonly used to reseal K-3 and K-4 inboard steering cylinders and select PSK11-12 cylinder applications. Use this kit to refresh internal sealing, help stop leaks at the rod gland, and restore smooth, consistent steering performance.

Always verify the cylinder model stamped on the barrel or end gland before ordering. If your stamp is unclear, send photos through our Tech Support Page.

Compatibility

• Fits: Hynautic K-3 and K-4 steering cylinders
• Also listed for: PSK11-12 cylinder applications
• Important: If you have a K-3 cylinder manufactured prior to 4-15-94, the correct kit may be KS-13. Confirm your cylinder revision before ordering.

What’s Included

• Seal and O-ring set for one cylinder (typical)
• Rod seal and wiper(s) as applicable
• Backup rings as applicable
• Retaining wire or clip as applicable

Note: Contents can vary slightly by cylinder revision. Reuse of hard parts is expected unless damaged.

Installation Tips

• Protect the rod: Any nicks or scratches can quickly damage new seals.
• Keep it clean: Cap open lines/ports and keep debris out of the cylinder while it is open.
• Lubricate seals: Lightly coat new seals with compatible hydraulic fluid before assembly.
• Inspect first: Rod pitting or bore scoring can cause repeat leaks even with new seals.

Maintenance Guidelines

• Verify cylinder alignment and mounting hardware to prevent side-loading the rod.
• Periodically inspect around the gland/wiper for early seepage.
• Bleed the steering system thoroughly after service to prevent spongy feel and uneven response.

FAQs

• Does KS-17 fit all K-3 cylinders? KS-17 is commonly used for K-3 cylinders, but revisions matter. If your K-3 is prior to 4-15-94, you may need KS-13. Confirm your cylinder stamp and revision.
• My cylinder still leaks after reseal - why? Common causes include rod pitting, bore scoring, incorrect seal orientation, or contamination during assembly.
• Not sure what you have? Send photos through our Tech Support Page and we will help identify the correct kit.

Related Hynautic Cylinder Seal Kits

Install Overview - Resealing a Hynautic Cylinder

This is a high-level overview to help you plan the job. Follow the Hynautic service manual for exact steps and specs.

1. Prep - Clean the exterior, secure steering, and protect the rod from scratches.
2. Depressurize - Relieve system pressure and cap lines to prevent contamination.
3. Disassemble - Remove retaining wire(s)/end cap per the manual and withdraw the rod and piston assembly.
4. Inspect - Check rod and bore condition. Replace damaged hard parts before reseal.
5. Reseal - Install new seals from KS-17 and lubricate with compatible hydraulic fluid.
6. Reassemble - Confirm smooth travel by hand, then refill and bleed the steering system.

Downloads and Resources

Questions?

• Tech Support: Tech Support Page
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