Sierra 18-3239 Water Pump Kit Merc 55-059
Sierra 18-3239 Water Pump Kit Merc 55-059 — Product description
Keep your outboard engine running cool and reliable with a high-quality water pump kit designed for seamless performance on the water. This aftermarket solution steps in as a direct fit for specific Mercury outboard models, delivering the essential coolant flow that prevents overheating during long days on the lake or open sea. Crafted with durable materials, it tackles the harsh marine environment, from saltwater corrosion to high-RPM demands, ensuring your boating adventures stay uninterrupted.
Boat owners know the frustration of a failing impeller—sudden temperature spikes, steam rising from the engine cowling, or reduced power output. This kit addresses those issues head-on, restoring optimal cooling efficiency without the premium cost of genuine factory parts. It's a smart choice for DIY mechanics and professional technicians alike, offering reliability that matches or exceeds original equipment.
Why This Water Pump Kit Stands Out
- Precision Engineering: Impeller, housing, and wear plate molded to exact specifications for perfect alignment and maximum water intake.
- Corrosion-Resistant Construction: High-grade stainless steel and reinforced rubber components built to withstand electrolysis and abrasive debris.
- Complete Kit: Includes everything needed for a full rebuild—impeller, key, liner, gaskets, and O-rings—for a hassle-free swap.
- Extended Service Life: Neoprene or urethane impeller options provide superior flex and longevity compared to standard rubber.
- Easy Maintenance Access: Drop-in design minimizes downtime, ideal for routine servicing before each season.
Unlike generic replacements that wear out prematurely, this kit uses proven materials trusted by marine pros. It promotes consistent engine temps, protects lower units from heat damage, and maintains peak performance across idle to wide-open throttle.
Perfect Fit for Your Engine
Engineered as a drop-in replacement, it mates flawlessly with select Mercury and Mariner 2-stroke outboards from the mid-20th century lineup. Verify your model against the kit's specs to confirm compatibility—common applications include 65-90 HP variants with standard rotation pumps. Always cross-check your service manual for gearcase specifics to avoid mismatches.
Pro Tip: Inspect your existing pump for telltale signs like cracked housings or glazed impellers before ordering. A fresh kit often reveals other lower unit needs, saving you from repeat teardowns.
Step-by-Step Installation Insights
Swapping out your water pump doesn't require a full lower unit overhaul. Here's a mechanic-approved approach:
- Prep Work: Drain gear lube, secure the outboard on a stand, and remove the lower cowling for access.
- Disassemble: Undo gearcase screws, tap off the water pump housing gently with a plastic mallet—avoid metal tools to prevent dings.
- Clean Thoroughly: Flush debris from the pump cavity and inspect the driveshaft for scoring.
- Assemble New Kit: Lubricate O-rings with marine grease, align the impeller key precisely, and torque housing bolts to spec (typically 84-108 in-lbs).
- Test Run: Prime the pump with a garden hose, fire up the engine, and check for strong telltale flow. Monitor temps on your first outing.
Tools needed: Socket set, gasket scraper, and thread locker. Total time: 30-60 minutes for experienced hands. If you're new to this, watch technique-focused videos from seasoned boaters for visual guidance.
Maximize Longevity with Smart Upkeep
A great pump kit shines brighter with proper care. Flush your engine after every saltwater trip to rinse salt buildup. Inspect the impeller annually or every 100 hours—look for chunks missing or hardening. Store your outboard flushed and dry during off-seasons to prevent dry-rot. Pair it with fresh gear lube and a zinc anode refresh for comprehensive lower unit health.
Bonus: Running the pump dry on purpose (briefly) at season's end ejects water, but never exceed 30 seconds to avoid impeller damage.
Frequently Asked Questions
What engines is this water pump kit compatible with?
It's a direct replacement for select Mercury 2-stroke outboards, particularly 65-90 HP models from earlier production runs. Always confirm with your engine's serial number and service manual.
What's included in the kit?
The complete assembly features an impeller, wear plate, housing, key, gaskets, O-rings, and necessary seals for a full installation.
How often should I replace the water pump impeller?
Replace annually or every 100 hours of operation, especially after heavy use or saltwater exposure, to prevent overheating failures.
Can I install this kit myself?
Yes, it's DIY-friendly with basic tools. Follow a step-by-step guide, ensure proper alignment, and test thoroughly afterward.
What are the signs of a failing water pump?
Watch for weak telltale stream, engine overheating, steam from the cowling, or unusual noises from the lower unit.
Is this kit suitable for freshwater and saltwater use?
Absolutely—its corrosion-resistant materials handle both environments effectively with regular flushing.
Does it match OEM performance?
It delivers equivalent or better flow rates and durability, often at a fraction of the cost, backed by marine industry standards.
SKU: NVN-4002612
MPN: 18-3239
UPC: 030999236906
Technical specifications
| Brand | Sierra Engine Parts |
| Model | Sierra 18-3239 Water Pump Kit Merc 55-059 |
| SKU / MFR# | 4002612 |
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