How Much Does Outboard Impeller Replacement Cost?
What it costs to replace an outboard water-pump impeller in 2026 — DIY parts-only versus shop labor, single versus twin engine, and what pushes the quote higher.
Short answer
Replacing an outboard's water-pump impeller typically runs about $240 to $650 per engine at a shop — a $57 to $137 parts kit plus roughly 1.5 to 2.5 hours of labor. Doing it yourself drops the cost to the kit price. Twin engines, saltwater corrosion, or a full water-pump kit push toward the high end.
Parts pricing follows published Mercury water-pump repair kits; the per-engine shop range and regional swing come from the calculator above — set your engine count and region for your own estimate.
Why the impeller matters more than the price
The impeller is a rubber pump that pushes cooling water through the engine. It hardens and cracks with age and dry starts, and a failed impeller can overheat and destroy a powerhead worth thousands. That is why most manufacturers call for replacement roughly every two to three years regardless of hours — the $240-ish job is cheap insurance against a four-figure repair.
What drives the cost up
- Engine count. Twin and triple rigs multiply the per-engine number directly.
- Lower-unit access. Some outboards need the gearcase dropped to reach the pump, adding labor.
- Saltwater and corrosion. Seized bolts and corroded housings turn a 1.5-hour job into 2.5+.
- Full water-pump kit vs impeller-only. Replacing the housing, wear plate, and gaskets (recommended) costs more than the impeller alone but is the durable fix.
DIY versus a shop
The part is inexpensive, so the decision is really about labor and risk. A DIY impeller swap on an accessible outboard is a common driveway job with basic tools, and it removes the entire labor line. The risk is reassembly — a misaligned housing or pinched gasket can run the engine dry. If the gearcase must come off, most owners hand it to a shop.
FAQ
How often should an outboard impeller be replaced?
Most builders recommend every two to three years or per the service manual, even if the old one looks intact — rubber degrades on a calendar, not just on hours.
Can I replace just the impeller instead of the whole water pump?
You can, and it is cheaper, but if the housing or wear plate is grooved the new impeller wears out fast. On an older engine the full kit is usually worth it.
Does engine count change the price a lot?
Yes — impeller service is quoted per engine, so a twin-engine boat is roughly double a single. Use the calculator above with your engine count to estimate the combined total.