Pipe Plug 1/4" NPT – Universal Marine Applications (Replaces 22-36382, 18-4256, 9-40545)

Product Details

This Pipe Plug 1/4" NPT – Universal Marine Applications is a brass fitting designed for universal marine engine applications. Compatible with Mercury Mercruiser engines including the 7LX 4BBL GM 350 V-8 '96 and similar models, this pipe plug provides a reliable seal for threaded openings in cooling, fuel, and hydraulic systems.

This aftermarket replacement directly interchanges with Mercury Quicksilver 22-36382, Sierra 18-4256, and GLM 9-40545.

• 1/4" NPT threaded connection for standard marine pipe fittings
• Brass construction resists corrosion in saltwater and freshwater environments
• Universal fitment across multiple marine engine brands and systems

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Technical Specs

Thread Size

1/4" NPT

Material

Brass

Thread Length

0.62"

Thread Specification

.250-18

Application

Universal Marine

Finish

Natural brass

What's in the Box

• 1 × Pipe Plug (1/4" NPT)

Installation Notes

1. Identify the 1/4" NPT threaded port requiring sealing or plugging on your engine block, manifold, or component.
2. Clean the threaded opening thoroughly, removing old sealant, debris, or corrosion.
3. Apply marine-grade thread sealant or PTFE tape to the plug threads in a clockwise direction.
4. Hand-thread the pipe plug into the port until snug, ensuring proper alignment to avoid cross-threading.
5. Tighten the plug using an appropriately sized wrench to the manufacturer's torque specification for brass fittings.
6. Do not overtighten, as brass is softer than steel and excessive torque may strip threads or crack the fitting.
7. Inspect for leaks after engine startup or system pressurization, and retighten if necessary.

Troubleshooting & FAQ

Will this plug fit my engine if I have a 1/4" NPT port?

Yes, this plug is designed for standard 1/4" NPT threaded openings and will fit any marine engine or component with matching threads. Always verify thread size and pitch before installation.

Can I reuse this pipe plug after removal?

While brass plugs can often be reused, inspect threads carefully for damage or deformation. Always apply fresh thread sealant during reinstallation to ensure a leak-free seal.

What torque specification should I use?

Consult your engine service manual for brass fitting torque values. Typical range for 1/4" NPT brass plugs is 7–12 ft-lbs, but always follow manufacturer guidelines to prevent thread damage.

Is PTFE tape or pipe sealant better for this application?

Both work effectively. PTFE tape is cleaner and easier to remove; marine-grade pipe sealant provides stronger resistance to vibration and thermal cycling. Choose based on your service environment and maintenance preferences.

What are signs this plug needs replacement?

Look for coolant, fuel, or oil seepage around the plug, visible corrosion or pitting on brass surfaces, or stripped threads. Replace immediately if any leak or thread damage is detected.

Can this be used in saltwater applications?

Yes, brass offers good corrosion resistance in marine environments. For extended saltwater exposure, inspect periodically and replace if dezincification (pink/red discoloration) occurs.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

• Verify images/specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.
• This is an aftermarket replacement, not an OEM component.
• Professional installation is recommended for safety and performance.

About Sea Sierra

• Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
• Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
• Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.