Mercury MerCruiser Seawater Pump Pulley – 8M0150724

Mercury MerCruiser Seawater Pump Pulley – 8M0150724

Part Number: 8M0150724
Brand: Mercury Marine / Quicksilver
Official Product Type: Seawater Pump Pulley – OEM
System: Raw Water Cooling / Accessory Belt Drive
Drive Type: Serpentine belt

About This Part

This is the genuine Mercury OEM seawater pump pulley for MerCruiser sterndrive engines equipped with a serpentine belt accessory drive system. The seawater pump (also called the raw water pump) draws water from outside the hull and circulates it through the engine’s heat exchanger to keep the engine at operating temperature. This pulley mounts on the seawater pump shaft and is driven by the serpentine belt — if the pulley is worn, cracked, or misaligned, the belt slips or tracks incorrectly, reducing raw water flow and risking engine overheating.

Compatible Applications

• MerCruiser 4.3L V6 – serpentine belt accessory drive models
• MerCruiser 5.0L V8 – serpentine belt accessory drive models
• MerCruiser 5.7L V8 – serpentine belt accessory drive models
• MerCruiser 6.2L V8 – serpentine belt accessory drive models
• MerCruiser 7.4L V8 – serpentine belt accessory drive models
• MerCruiser 8.2L V8 – serpentine belt accessory drive models

Always verify fitment using your engine serial number. MerCruiser engines of the same displacement can use different accessory drive configurations depending on model year and cooling setup. Confirm part number 8M0150724 appears on the Mercury MerCruiser parts diagram for your engine before ordering.

Serial Number / Fitment Note

Locate your MerCruiser engine serial number on the engine block tag or flame arrestor decal. Cross-reference against the Mercury MerCruiser parts diagram for your engine model to confirm this is the correct seawater pump pulley. Some MerCruiser engines use a V-belt drive rather than a serpentine belt — this pulley is for serpentine belt systems only.

System & Diagram Position

This pulley is found in the Raw Water Cooling / Accessory Belt Drive section of the Mercury MerCruiser parts diagram. It mounts on the seawater pump shaft and is driven by the serpentine belt alongside the power steering pump pulley, tensioner pulley, and idler pulley. Correct pulley alignment across the entire accessory drive is critical — a misaligned seawater pump pulley will cause belt wear and tracking issues that affect all belt-driven accessories.

Supersedes / Cross-Reference Numbers

8M0150724 is the current Mercury OEM part number for this seawater pump pulley. If your parts diagram shows an earlier number, 8M0150724 is the current replacement. Always confirm against your engine’s diagram and serial number.

When to Replace

• Visible cracks, chips, or corrosion damage to the pulley face or hub
• Belt grooves worn smooth — causes belt slip, squeal, and reduced pump speed
• Pulley wobble or runout when spun by hand (indicates a bent hub or worn pump shaft bearing)
• Belt misalignment traced to the seawater pump pulley position
• Engine overheating caused by reduced raw water flow from belt slippage
• Replacing the seawater pump — inspect the pulley at the same time and replace if worn

Service Interval

Inspect the seawater pump pulley annually as part of routine belt and cooling system service. Replace whenever wear, damage, or misalignment is found, or whenever the seawater pump is serviced or replaced. The serpentine belt should be inspected at the same interval and replaced if it shows cracking, glazing, or fraying.

Installation Notes

• A pulley puller is required to remove the old pulley — do not pry or hammer it off, as this damages the pump shaft and bearing
• A pulley press or installer tool is required to seat the new pulley to the correct depth on the shaft
• Confirm pulley alignment with all adjacent pulleys using a straightedge before reinstalling the serpentine belt
• Inspect the serpentine belt for wear and replace if it has been running on a damaged or misaligned pulley
• After installation, run the engine and verify normal coolant temperature and raw water flow at the exhaust

Related Parts

• Mercury MerCruiser Power Steering Pump Pulley – 8M0150723
• Mercury MerCruiser Serpentine Belt Pulley Kit – 8M0150824
• Quicksilver Water Pump Pulley – 8M0153706
• Mercury MerCruiser Quicksilver Tensioner Pulley – 865777
• Mercury MerCruiser Quicksilver Serpentine Belt – 865615Q03
• Mercury MerCruiser Quicksilver Serpentine Belt – 8M0045986
• Mercury MerCruiser Quicksilver Serpentine Belt – 8M0135333
• Mercury MerCruiser Sea Pump Pulley – 8M0141645

Technical FAQ

What happens if the seawater pump pulley fails while underway?
If the pulley cracks or the belt slips off, the seawater pump stops circulating raw water through the cooling system. The engine will overheat within minutes. Overheating can cause head gasket failure, warped cylinder heads, and serious internal engine damage. This is a safety-critical component — inspect it regularly and replace at the first sign of wear.

Do I need a special tool to change this pulley?
Yes. A pulley puller is required to remove the old pulley without damaging the pump shaft. A pulley press or installer is required to seat the new pulley correctly. Attempting to hammer the pulley on or off will damage the pump bearing and shaft, turning a simple pulley replacement into a full pump replacement.

Should I replace the serpentine belt at the same time?
Yes, if the belt has been running on a worn or damaged pulley. A damaged pulley surface accelerates belt wear. Since the belt must be removed to replace the pulley, it’s good practice to install a new belt at the same time — especially at the start of the season or at the 300-hour service interval.

How do I confirm this is the right pulley for my engine?
Look up your engine serial number in the Mercury MerCruiser parts diagram under the accessory belt drive or raw water cooling section. The seawater pump pulley part number will be listed there. If you’re unsure, contact us with your serial number and we can help confirm the correct part.

Parts Desk Insights

Best use case: This pulley is the right part for a MerCruiser sterndrive that is showing belt tracking issues, belt squeal from the cooling side of the accessory drive, or reduced raw water flow that traces back to belt slippage rather than the pump impeller. It’s also the correct part to order alongside a seawater pump replacement — if the pump has been running hot or dry, the pulley should be inspected and replaced at the same time.

Common issues: Customers sometimes order this pulley without confirming their engine uses a serpentine belt drive — older MerCruiser engines use a V-belt system and require a different pulley. A second common issue is replacing the pulley without replacing the serpentine belt; if the pulley was worn or misaligned, the belt has been running under stress and should be replaced as a set. Also watch for customers who overlook the pulley when diagnosing overheating — a slipping seawater pump belt is a frequent cause of mild overheating that gets misdiagnosed as an impeller or thermostat issue.