22275078 Pump Piston | Genuine Volvo Penta Part

🔧 Product Description

The strength required to steer a boat with a hydraulic steering system is inversely proportional to the number of turns of the wheel lock-to-lock. Wheel turns are determined by the ratio between the cylinder volume, the pump displacement and the free movement of the steering device. A large cylinder volume with a small pump displacement gives more wheel turns; a small cylinder volume with a large pump displacement gives fewer. Fewer wheel turns means quicker steering response but more effort; more wheel turns means slower response but less effort. The helm pumps are available in three displacement sizes - 28 cc, 33 cc and 39 cc - each in three mountings: front mount, rear mount and tilt mount. This is the 39 cc tilt mount pump, with 7 pistons, a 70 bar relief valve setting and a maximum wheel diameter of 508 mm.

⚙️ Key Features

• 39 cc displacement per wheel revolution
• Tilt mount
• Seven piston pump
• 70 bar relief valve setting
• For steering wheels up to 508 mm in diameter
• Requires tilt mechanism 22299003, ordered separately
• 5.312 kg
• Replaces 21639578
• Tilt mount helm pump
• 7 pistons
• Maximum wheel diameter 508 mm
• 5 kg
• Displacement per rev: 39 cc
• Max wheel diameter: 508 mm
• Pistons: 7
• Mounting: Tilt mount helm pump
• Relief valve setting: 70 bar
• Weight: 5 kg
• Fits: Volvo Penta hydraulic steering systems

🔌 Function

Converts steering wheel rotation into pressurised hydraulic oil flow to the steering cylinder, on a helm whose angle can be adjusted.

⚠️ Common Signs of Failure

• Heavy, notchy or inconsistent steering
• Wheel turning without the drive following, from internal bypass
• Hydraulic oil weeping at the shaft seal or the port fittings
• Helm will not hold its set tilt angle
• Air drawn into the circuit giving a spongy helm

🛠️ Service Notes

• Tilt mechanism 22299003 has to be ordered separately for any of the three tilt mount pumps
• The same 39 cc pump is 22275072 in front mount and 22275075 in rear mount
• Bleed the circuit fully after fitting and check the level with the steering held hard over each way
• Tilt mechanism 22299003 is required and must be ordered separately
• Displacement and mounting together are the product: the same 39 cc displacement is also listed as 22275072 and 22275075, and the other tilt mount pumps are 22275076 and 22275077
• Tilt mount pumps are rated to a 508 mm wheel against 711 mm for the front and rear mount pumps
• Cylinder volume and pump displacement together set how many turns the wheel takes lock to lock

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 22275078 → Supersedes 21639578 → Supersedes 21135052 → Supersedes 3809980

OEM / Related Numbers

• 21639578 earlier number superseded by this part
• 21135052 earlier number superseded by this part
• 3809980 earlier number superseded by this part
• 22299003 (required tilt mechanism)

📦 Condition

• Genuine Volvo Penta part
• Brand new
• Supplied in original or equivalent packaging