Customer Service
+1 888 812 6287
Required for fitment review to confirm compatibility.
OBR Mercury F150 4-stroke lower unit by engine family, shaft length, rotation, and condition. This listing includes ME-G4 replacement gearcases for selected standard F150, F150 counter-rotation, F150 Pro XS, and F150 SeaPro applications. New and remanufactured configurations are available in 20-inch L and 25-inch XL versions, depending on the selected SKU.
Do not select a lower unit using horsepower or model year alone. Submit the complete engine model and serial number and confirm the existing shaft length, rotation, and original gear ratio before ordering. The explicitly identified F150 counter-rotation configuration is ME-G4-16A with a 25-inch XL shaft.
SEI SE90-221 is a separate product family and is not an alternate part number for these OBR ME-G4 gearcases. OBR gearcases ship without gear lubricant and must be filled according to the engine manufacturer’s requirements before operation.
Elite Versatility: Optimized for F150, PRO XS, and SeaPro high-hour applications.
Twin-Engine Ready: Specifically designed to support Counter Rotation (LH) for perfect thrust synchronization.
Saltwater Tough: Reinforced with an advanced marine finish for maximum corrosion protection in offshore environments.
Confirm the following application before ordering:
New versions use the -N suffix and remanufactured versions use the -R suffix. Exact fitment must be confirmed using the complete engine model and serial number. A year, horsepower, or visual match by itself is not sufficient.
Before dispatch, the selected SKU should be checked against the engine model and serial information supplied with the order. If the information is incomplete or conflicts with the selected configuration, the shipment should be paused and the customer contacted for clarification.
The shipping carton and SKU label should be inspected before release to the carrier. The customer should be informed that the gearcase ships without gear oil and must be filled with the engine manufacturer’s required lubricant before installation or operation.
When the shipment arrives, inspect the carton for punctures, crushing or water exposure. Photograph visible damage, retain the carton and packaging, and report shipping damage before the unit is installed. Do not install or operate an incorrect or visibly damaged shipment.
Once the order has cleared the fitment and packaging review, tracking information should be provided to the customer using the contact details submitted at checkout. The customer should verify the delivery address, monitor the carrier’s tracking updates and arrange to receive the shipment when required. Any address correction or delivery-request change should be submitted before carrier pickup, because changes made after dispatch may cause additional delays or fees.
| Specification | Mercury F150 4-Stroke Lower Units | Standard & Counter Rotation |
|---|---|
| Manufacturer | OBR Parts & Marine |
| Compatible Engine Brand | Mercury |
| Product Family | OBR ME-G4-15, ME-G4-16, ME-G4-16A, ME-G4-17, ME-G4-18, ME-G4-33 and ME-G4-34 |
| Conditions | New and remanufactured |
| Engine Applications | Selected Mercury F150, F150 counter-rotation, F150 Pro XS and F150 SeaPro four-stroke applications |
| Horsepower | 150 HP |
| Years | F150 and Pro XS are supplier-cataloged as 2011-Up; SeaPro is supplier-cataloged as 2022-Up. Exact serial fitment is required. |
| Rotation | ME-G4-15 and ME-G4-16 are standard rotation; ME-G4-16A is counter or left-hand rotation. Pro XS and SeaPro rotation: VERIFY BEFORE PUBLISHING |
| Shaft Options | 20-inch L and 25-inch XL, depending on SKU |
| SeaPro Identification | Supplier listing identifies serial number 3B111735-Up for ME-G4-33 and ME-G4-34 |
| Gear Lubricant | Ships without gear oil; fill with the manufacturer-required lubricant before operation |
| Warranty | OBR two-year limited warranty, subject to written terms |
| Major Exclusion | SEI SE90-221 or SE221 is not part of this OBR ME-G4 product family |
Start with the exact engine family. A standard Mercury F150, an F150 counter-rotation application, an F150 Pro XS and an F150 SeaPro may all be rated at 150 horsepower, but they do not automatically use the same replacement gearcase.
Next, match the existing driveshaft length. The ME-G4-15, ME-G4-17 and ME-G4-33 families are listed with a 20-inch L shaft. The ME-G4-16, ME-G4-16A, ME-G4-18 and ME-G4-34 families use a 25-inch XL configuration. Shaft length must be confirmed from the engine and existing gearcase—not estimated from the boat.
Rotation is equally important. The ME-G4-16A is the listed counter-rotation or left-hand F150 configuration. Do not select it simply because the engine is mounted on a particular side of a twin-engine boat.
Finally, choose new or remanufactured condition and submit the complete engine model and serial number. The original gear ratio and spline configuration must also be confirmed before installation. These steps are more reliable than ordering from horsepower, year or appearance alone.
Use CTRL + F or search below to find your engine model
Loading compatibility data...
No results found. Please try a different search term.
The product selection made it simple to confirm the SE216 unit configuration for my Mercury F150 4-Stroke. The 1.92:1 gear ratio and 20-inch shaft length matched my original gearcase perfectly. Be sure to verify your gear rotation and shaft specs before ordering.
Finding the correct counter-rotation lower unit for a twin Mercury F150 setup can be tricky, but Mariners Warehouse fitment assistance helped confirm my exact serial number range. Installation went smoothly and water testing showed zero issues.
The SE216 unit arrived early and was bolted securely to a sturdy foam crate. The 25-inch shaft and splines aligned without any hesitation on my 2018 Mercury F150 4-stroke. Breaking it in according to SEI guidelines keeps it running whisper quiet.
The lower unit performs excellently on the water with smooth shifting. The only minor inconvenience was taking extra care while removing the shipping bracket, but the overall product and 1.92:1 gear ratio accuracy make it well worth it.
Replaced a worn OEM lower unit on a 150 HP 4-stroke Mercury. The fitment guidelines on the page accurately explained bullet size and gear ratio checks needed prior to checkout. Over 50 hours in service now with zero problems.
Need Help?
Finding the right replacement part shouldn't be frustrating. If you can't locate the marine part you need, our experienced support team is here to help. Whether you have a part number, engine model, or simply need expert guidance, we'll help you find the correct replacement so you can get back on the water with confidence.
Trusted by 50,000+ boat owners across the USA
Our team has years of experience in marine parts.
We respond quickly to get you the help you need.
We make sure you get the right part the first time.
Access to 50,000+ marine parts & accessories.
Thanks for subscribing!
This email has been registered!
