How to Care for Your Jet Ski: A Complete Owner's Guide

Jet skis are simple to enjoy and easy to neglect. Most of the expensive failures UK owners run into — corroded cooling passages, a dead battery that takes the ECU with it, a chewed wear ring, a seized supercharger clutch — start with routine care that got skipped a few rides in a row.

This guide covers what to do after every ride, what to check monthly, and what to hand over to a workshop. Intervals and fluid specifications differ between manufacturers and model years, so treat this as the routine and your owner's manual as the authority.

After every ride: flush and rinse

Flushing is the single most important habit, especially in UK coastal water.

1. Park the ski on the trailer, nose slightly high so water drains back out.
2. Connect the hose to the flush fitting before you turn the water on.
3. Start the engine, then turn the water on. Reverse that order and you risk water backing into the exhaust and engine.
4. Run for the time your manual specifies — usually a couple of minutes.
5. Turn the water off first, then let the engine run a few seconds to clear residual water, then shut down.
6. Blip the throttle gently a couple of times to clear the exhaust if your manual recommends it.

Then rinse the hull, deck, seat, handlebars, intake grate and trailer with fresh water. Salt left in seams and fasteners keeps working long after the ski is dry.

Salt water vs fresh water

Salt water is far harder on a ski: it corrodes aluminium and steel, attacks electrical connections, and leaves deposits in the cooling circuit. Ridden in salt, a ski needs flushing every single time, plus a rinse of the trailer.

Fresh water is gentler but not maintenance-free. Silt, weed and sand still block intakes, and inland water often means shallow launches that pick up debris into the pump.

Either way, dry the ski, leave the seat off for a while so moisture escapes, and treat exposed metal and electrical connections with a marine corrosion inhibitor.

Oil and fluids

• Check engine oil with the ski level and follow your manual's procedure — many four-strokes require a short warm-up and a specific settling time before reading the dipstick.
• Top up only with the grade and specification your manual lists.
• Look for milky oil. That can indicate water ingress and means stopping and getting it inspected rather than running it.
• Two-stroke owners: keep the oil injection reservoir topped and check the lines for kinks or air.
• Check coolant level on closed-loop cooling systems, and inspect hoses for softness or chafing.

Battery maintenance

Batteries are the most common reason a ski will not start in spring.

• Keep the battery on a smart maintenance charger when the ski is not in regular use.
• Clean terminals and protect them with a thin smear of dielectric grease.
• Check the battery is strapped down tightly — vibration destroys plates.
• If the ski is stored somewhere cold and damp, take the battery out and keep it indoors.

Hull inspection

Every few rides, look over the hull properly with the ski off the trailer bunks if you can:

• Gelcoat chips and scratches from slipways — small ones can be sealed, deeper ones need a proper laminate repair.
• Stress cracks around the pump tunnel, ride plate and sponson mounts.
• Loose or corroded fasteners.
• Drain plugs: present, clean threads, seals in good condition. Fit them before launch, every time.

Hairline cracks that keep growing are structural, not cosmetic — get them looked at before water gets into the laminate.

Jet pump and intake checks

• Inspect the intake grate for weed, line, plastic and stones.
• Spin the impeller by hand (engine off, lanyard removed) and feel for grinding or play in the bearing.
• Check the wear ring clearance. A worn ring is the usual cause of "it still revs but it's lost top speed".
• Check for fishing line wrapped around the driveshaft behind the impeller — it cuts seals and lets water into the pump bearing.
• Change pump oil at the interval your manual gives.

Trailer care

The trailer lives in salt water and gets forgotten.

• Rinse thoroughly, including inside the frame where possible.
• Check bearings for play and grease at the manufacturer's interval; replace seals if grease looks milky.
• Check lights, wiring, the coupling, safety cable and the tyres, including the spare.
• Inspect bunks or rollers for wear that could mark the hull, and check the winch strap for fraying.

Storage between rides

For short-term storage, keep the ski covered, out of direct sun where possible, with the drain plugs out and the seat cracked open so it can breathe. Chock the trailer and take the weight off the tyres if it will sit for months.

For longer periods, damp is the enemy — a well-ventilated, dry space beats a sealed cover that traps condensation. Plenty of UK owners use a professional storage yard over winter.

Winterisation

UK winters mean freeze risk. A typical winterisation includes:

• A final thorough flush.
• Fuel stabiliser added and the engine run so treated fuel reaches the system.
• Fogging or internal corrosion protection where the manufacturer specifies it.
• Water drained from the cooling circuit and exhaust in line with the manual.
• Battery removed and maintained on charge.
• Cleaning, protecting and covering the ski, with vents left so it can breathe.

Procedures vary considerably between manufacturers and models — antifreeze routines in particular are not universal. Check your manual or have a workshop do it.

Servicing

Servicing intervals are set by hours and by time, and each manufacturer sets its own. Ignore anyone quoting a single "correct" interval for all skis, including this page — look it up for your model.

A routine service typically includes an oil and filter change, spark plugs, cooling and exhaust checks, pump and driveline inspection, hull and hardware checks, and a diagnostic scan. Supercharged four-strokes have additional supercharger service requirements at their own interval.

When to use a professional

Do it yourself: rinsing, flushing, fluid checks, battery care, visual inspections, trailer basics.

Get a specialist involved for:

• Any water in the oil, overheating, or unexplained loss of power.
• Fault codes you cannot clear, or intermittent electrical problems.
• Supercharger service on supercharged skis.
• Structural hull damage or repeated cracking.
• Full winterisation if you are not confident with the procedure.
• Engine rebuilds and pump bearing work.

A workshop that knows your engine family will find things a general inspection misses, and their diagnostic software reads far more than a generic scanner.

Quick routine

• Every ride: flush, rinse, dry, plugs out, cover.
• Monthly in season: oil level, battery, intake and impeller, hull and fasteners, trailer lights and tyres.
• Annually or by hours: full service, pump oil, bearings, diagnostic check.
• Before winter: winterisation, battery out, dry storage.