Sierra 1236 Gearcase Oil Drain Screw — Outboard & Cobra Sterndrive Lower Unit

Sierra 1236 Gearcase Oil Drain Screw — Outboard & Cobra Sterndrive Lower Unit

Part Number: 1236  |  SKU: 47-1236
Brand: Sierra
System: Lower Unit / Gearcase Oil Service
Supplied as: One (1) drain screw

The Sierra 1236 is a replacement gearcase oil drain screw for outboard and Cobra-style sterndrive lower units. A stripped, corroded, or leaking drain screw is the most common reason a routine gearcase oil change turns into a bigger job — having the correct replacement on hand before you start draining keeps the service clean and the gearcase sealed tight when you’re done.

Specifications

• Part number: Sierra 1236 (SKU 47-1236)
• Type: Gearcase / lower unit oil drain screw
• Weight: ~5 g
• Supplied as: One (1) screw

Key Features

• Direct-fit replacement — matches original drain screw profile for correct thread engagement and sealing
• Compatible with outboard lower units and Cobra-style sterndrive gearcases that specify the Sierra 1236 drain screw
• Designed for use during routine gearcase oil changes and post-season service

Compatible Applications

• Outboard lower units specifying the Sierra 1236 drain screw — confirm by matching your existing drain screw or OEM part number
• OMC Cobra sterndrive gearcases specifying the Sierra 1236 drain screw — verify against your engine service manual or parts diagram
• Always confirm thread pitch, thread diameter, and head style match your existing screw before installing

Fitment Notice

Sierra offers several gearcase drain screws for different outboard and sterndrive applications. Confirm your existing drain screw part number, thread specification, and gearcase model before ordering. Do not substitute a nearby Sierra drain screw number without verifying the thread dimensions — an incorrect screw will not seal properly and can damage the gearcase drain port.

Service Interval

Inspect the drain screw at every gearcase oil change (typically annually or every 100 hours). Replace whenever you find: stripped or rounded drive recess, damaged threads, corrosion that prevents a clean seal, or deformation from over-tightening. Always replace the drain screw gasket at the same time — reusing an old gasket is a leading cause of post-service gearcase leaks.

Installation Notes

• Thread the screw in by hand first to confirm correct thread engagement before applying torque
• Do not cross-thread — the gearcase housing thread is the most expensive part of this repair
• Torque to the engine manufacturer’s specification; do not over-tighten
• Always install a new drain screw gasket with the screw — do not reuse the old one
• Check for leaks after the first water test following service

Related Parts

• Gaskets & seals (replace at every oil change):
  • Sierra Oil Drain Screw Gasket – 47-4698
  • Sierra Oil Drain Screw Gasket 47-469819 — 50-Pack
  • Sierra 47-29459 Drain Screw Gasket — OMC & Mercury/Mariner, 2-Pack
• Other Sierra gearcase drain screws:
  • Sierra 2244 Oil Drain Screw
  • Sierra 2374 Magnetic Oil Drain Screw
  • Sierra 2375 Oil Drain Screw
  • Sierra 2378 Magnetic Oil Drain Screw
  • Sierra 2387 Oil Drain Screw

Technical FAQ

Q: How do I know if the Sierra 1236 is the correct drain screw for my engine?
A: The safest method is to match your existing drain screw or look up your engine model and serial number in the Sierra marine parts catalog. The thread diameter, thread pitch, and head style must all match your gearcase drain port.

Q: Do I need a new gasket when I replace the drain screw?
A: Yes. The drain screw gasket or sealing washer should be replaced every time the screw is removed. Reusing an old, compressed gasket is a common cause of gearcase oil leaks after service. See the gasket options linked above.

Q: My drain screw is stuck — can I force it?
A: Do not force a stuck drain screw. Use penetrating oil and the correct-fitting driver to avoid stripping the drive recess or damaging the gearcase housing threads. If the screw is seized, consult a marine technician before proceeding.

Q: What is the difference between a standard and magnetic drain screw?
A: Magnetic drain screws (such as the Sierra 2374 or Sierra 2378) attract fine metallic wear particles from the gearcase oil, which can be a useful early indicator of internal wear. Not all gearcases are designed for magnetic screws — confirm compatibility before substituting.

Parts Desk Insights

Best use case: This is the go-to replacement when a drain screw is stripped, corroded, or leaking on an outboard or Cobra-style sterndrive gearcase that specifies the Sierra 1236. It’s a low-cost fix that prevents what would otherwise become a gearcase housing repair. Most customers order it as part of a pre-season or end-of-season gearcase oil service.

Common customer issues: The most frequent call-in is customers who have removed the old screw and then realize they need the matching gasket too — always confirm whether they have a replacement gasket before the order ships, and offer the appropriate Sierra gasket from the related parts above. The second most common issue is customers ordering by part number alone without verifying the thread spec against their gearcase — ask for the engine make, model, and year to cross-check before dispatching. If the drain port threads are damaged, a drain screw alone will not resolve the leak; that’s a thread repair or housing job.