Polaris PWC jet pumps - components, versions and variations

URL link to this web page ==> Polaris PWC jet pumps - components, versions and variations

The first generation jet pumps from Polaris used 146mm diameter impellers, and were only used in 1992 (SL650) and 1993 (SL650, SL750). Those pumps are known as the non-modular 146mm jet pumps.

Note: The 148mm jet pumps are more efficient than the original 146mm pumps, and provide more thrust from the same engine power. 1992-1993 hulls can be upgraded with the 148mm pump, but the correct 148mm impeller must be used to match the original engine power (SL 650 or SL 750).

Note: 146mm impellers can not be used in 148mm jet pumps, nor can 148mm impellers be used in non-modular 146mm pumps.

1994 through 2004 Polaris PWC use 148mm diameter impellers in 'modular' jet pumps

The impeller blade design and blade pitch (angle) is matched to the engine power and hull model such that the impeller provides maximum thrust just as the engine reaches maximum RPM and power. If the engine power is changed the impeller must also change to maintain optimal engine RPM at full throttle.

Each Polaris impeller has a part number which indicates the blade pitch and engines/models it is meant for.

The impeller fits very snugly within the jet pump. Optimal clearance (space) between the blade outer edges and the surrounding metal 'wear ring' is .010 inches or less. Gaps larger than .020 inches are considered excessive. Excess blade clearance causes the jet pump thrust to be reduced. Depending on what is worn the impeller can be repaired or replaced. Worn impellers can be refurbished to restore clearance. The wear ring should be replaced if worn or badly grooved.

On 'short' jet pumps the wear ring is also the base section of the jet pump, and is bolted to the hull.

Extended jet pumps typically use the extension section as the wear ring around the impeller (except Pro 785).

All Polaris jet pumps came stock with either the aluminum 5-vane stator (painted black) or the stainless steel 6-vane stator.

The five vane (fixed blade) stator in the modular jet pump is made from aluminum, and was stock on many models (including all models 1994-1996). A higher performance six vane Stainless Steel stator is generally found on models with high output engines and/or upgraded jet pumps. The six vane SS stator is considered an upgrade over the five vane aluminum stator, and they are otherwise interchangeable.

Attached to the back of the stator is the tail cone.

Upgrade and aftermarket stators were made in 7, 8 and 12 vane versions. All stators except the aluminum five vane version are stainless steel. Generally speaking jet pump stators with more vanes provide better rough water performance (hook up), but beyond six vanes the impeller's trailing edge blade profile must be matched to the stator vane profile. There are different length
impeller spacers which can be used to achieve the desired clearance between impeller and stator when using stators with more than six vanes.

'Extended' jet pumps have a round extension section (
four inches long) positioned in front or behind the stator. Aluminum extensions are usually painted black while the SS extensions are normally unpainted metal. They are interchangeable, but the SS versions is preferred for use in salt water (less corrosion). The aluminum extensions have a thin SS inner liner. If corrosion develops between the liner and aluminum shell the liner can bulge inwards and scrape against the impeller blades.

Non-extended 'short' jet pumps can be upgraded to extended. In addition to the extension itself, other 'longer' parts are required, such as longer drive shaft, longer cooling water tube, steering cable, etc. Often upgrading to an extended jet pump is combined with changing the hull ride plate, which sits directly below the jet pump.

The impeller is mounted on the threaded end of the stub shaft, which rides in a bearing and seal assembly located inside the hub of the stator. The impeller is torqued to 100 ft-lbs on the stub shaft.

It is important that the impeller (stub shaft) bearings turn smoothly with zero play, wobble, grinding, or noise. There are double shaft seals installed into the stator hub to keep water out.

The tail cone is also sealed with an o-ring and in later years also has a flat rubber gasket.

Once the seals fail and water gets into the bearing area the bearings and seals must be replaced with new.

The pump 'exit nozzle' is bolted directly to the back of the jet pump body (usually right behind the stator). Inside the exit nozzle on the right hand side is a plastic mesh screen that filters water for the engine cooling system. This screen must be kept clear.

Depending on the PWC model, there may be two, one, or even no bilge siphon tubes. These are pencil sized aluminum tubes that stick into the middle of the exit nozzle water flow on an angle. When the engine is pumping water through the jet pump these siphon tubes develop a mild suction, which is used to suck water out of the the bilge area inside the hull.

Behind the pump exit nozzle is the steering nozzle. Some models also have a 'trim' nozzle combined with the steering nozzle. Trim is an adjustment of the angle the water jet exits the jet pump. It allows the nose angle of the hull to be raised or lowered to match riding conditions. Polaris calls the electrically controlled trim nozzle system 'Quick Trim', with an Up-Down rocker switch on the left handlebar.

Some jet pumps also have a thin 'wedge' section sandwiched right in front of the exit nozzle. The wedge acts like a permanent trim adjustment, raising the bow angle slightly to optimize handling and speed.

Many models also have a reversing bucket at the very back of the jet pump. When lowered into reverse position the bucket directs thrust from the jet pump forward, causing the hull to move backwards.

Drive shafts
5131227 Hurricane drive shaft. It's 32 5/8 inches long