Sierra 18-3633 3633 Mercury Thermostat Kit

SKU: 4003704 - UPC: 808282375386 - MPN: 18-3633
$63.39 $72.29 ( / )

Available Stock : 87

Discover Reliable Cooling for Your Mercury Outboard with the Sierra 18-3633 Thermostat Kit Keeping your Mercury outboard engine at the optimal temperature is crucial for peak performance on the water. Overheating can lead to costly repairs, reduced power, and frustrating downtime during those long fishing trips or family cruises. The...
Sierra Engine Parts
Same Day

Shipping (3PM)

Free Returns

Within 30 days

Sierra 18-3633 3633 Mercury Thermostat Kit Product Description

Discover Reliable Cooling for Your Mercury Outboard with the Sierra 18-3633 Thermostat Kit

Keeping your Mercury outboard engine at the optimal temperature is crucial for peak performance on the water. Overheating can lead to costly repairs, reduced power, and frustrating downtime during those long fishing trips or family cruises. The Sierra 18-3633 thermostat kit steps in as a dependable aftermarket solution, engineered to mimic the exact specifications of original equipment while standing up to the harsh marine environment.

Crafted from high-quality materials like corrosion-resistant brass and premium gaskets, this kit ensures precise temperature regulation. Whether you're dealing with a sluggish engine that runs too cool or one that's prone to boiling over in summer heat, swapping in this thermostat restores factory-like efficiency without the premium price tag.

Standout Features of the Sierra 18-3633 Kit

  • Precision-Engineered Thermostat: Opens and closes at the exact rated temperature to maintain ideal coolant flow, preventing thermal shock.
  • Complete Kit Contents: Includes thermostat, O-rings, gaskets, and housing components for a seamless replacement job.
  • Marine-Grade Durability: Built to resist saltwater corrosion, vibration, and constant water exposure common in outboard applications.
  • Direct Fit Design: Matches OEM dimensions for plug-and-play installation on compatible Mercury models, saving you hours in the engine bay.
  • Quality Assurance: Sierra's rigorous testing ensures reliability, with thousands of boaters trusting these parts season after season.

Real-World Benefits for Boaters and Mechanics

Imagine heading out on a perfect dawn patrol only to notice your temp gauge climbing— that's a nightmare avoided with this thermostat kit. It promotes even heat distribution, extending the life of cylinder heads, impellers, and exhaust components. Fuel efficiency improves as the engine runs smoother, and you'll notice quicker warm-ups for better cold-start performance.

For DIY enthusiasts, the kit's straightforward design means you can tackle the swap with basic tools during a weekend maintenance session. Pros appreciate the consistent quality that cuts callback time, making it a staple in marine repair shops. Unlike some generics that fail prematurely, Sierra parts deliver proven longevity, backed by boaters who've run them through brutal conditions like offshore racing or commercial fishing.

Pro Tips for Optimal Thermostat Performance

To get the most from your Sierra 18-3633 installation:

  1. Always flush the cooling system first to remove debris that could gum up the new thermostat.
  2. Inspect hoses and the water pump impeller while you're in there—preventive maintenance multiplies your engine's reliability.
  3. Test in a barrel or on muffs post-install to verify proper opening before hitting open water.
  4. Monitor temps during the first few outings, as air pockets can mimic issues until fully bled.

Regular checks like these keep your Mercury humming reliably, trip after trip.

Frequently Asked Questions

What engines is the Sierra 18-3633 thermostat kit compatible with?

This kit fits a range of Mercury outboard models—check the Sierra catalog for your specific engine serial number to confirm exact fitment, ensuring seamless integration.

How does this thermostat prevent engine overheating?

It regulates coolant flow by opening at the precise temperature threshold, allowing proper circulation to dissipate heat efficiently while closing to retain warmth during startup.

Is the Sierra 18-3633 kit easy to install?

Yes, its direct-fit design and included seals make it straightforward for those with basic mechanical skills, typically a 1-2 hour job with common tools.

What materials make this thermostat kit corrosion-resistant?

High-grade brass construction paired with robust rubber O-rings and gaskets withstands saltwater, freshwater, and constant submersion without degrading.

Why choose Sierra over other aftermarket thermostat kits?

Sierra replicates OEM standards with superior testing and materials, offering boaters peace of mind through unmatched reliability and value in marine applications.

Can I use this kit in both freshwater and saltwater?

Absolutely—its marine-tough build handles both environments, making it versatile for inland lakes or coastal adventures.

What signs indicate I need a new thermostat?

Look for erratic temperature readings, poor warm-up, overheating under load, or visible leaks around the housing—these are classic symptoms signaling replacement time.

Upgrade Your Engine's Cooling Today

Don't let a faulty thermostat sideline your Mercury outboard. With the Sierra 18-3633 kit, you're investing in smooth operation, fewer headaches, and more time enjoying the water. Trusted by seasoned captains and weekend warriors alike, it's the smart choice for maintaining engine health.

See Sierra catalog for complete application information.



Save $8 when you buy the Sierra 18-3633 3633 Mercury Thermostat Kit for only $63 from NVN Marine! Same day shipping before 3pm.

Sierra 18-3633 3633 Mercury Thermostat Kit Technical Specifications

Type: 

Engine | Cooling / Thermostats / Impellers

Vendor: 

Sierra Engine Parts

Weight: 

0.5 lb

Replaces: 

8M0090819

Application: 

Mercury

Sierra 18-3633 3633 Mercury Thermostat Kit User Reviews

Sierra 18-3633 3633 Mercury Thermostat Kit Shipping & Return

Shipping Weight: 

0.5 lb

Box Sizes: 

3.00 (h) x 4.00 (w) x 4.00 (l)

Cubic Feet: 

48.0

Returnable: 

Yes

For detailed shipping policy please check our Shipping Policy and you can find our Return and Refund Policy here.

Sierra 18-3633 3633 Mercury Thermostat Kit

$63.39 $72.29 ( / )