Piston, Starboard .030 Oversize – Fits Mercury 105-Jet, 135 & 150 HP V-6 Outboards (Replaces 765-7445T11, 7445A11)
Piston, Starboard .030 Oversize – Fits Mercury 105-Jet, 135 & 150 HP V-6 Outboards (Replaces 765-7445T11, 7445A11) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Piston, Starboard .030 Oversize – Fits Mercury 105-Jet, 135 & 1...
Product Details
This Piston, Starboard .030 Oversize – Fits Mercury 105-Jet, 135 & 150 HP V-6 Outboards is designed for specific Mercury/Mercruiser V-6 outboard engines, including 105-Jet, 135 HP, and 150 HP models. It is intended for starboard (right) side cylinders that have been bored .030 inches oversize for repair or rebuilding.
It serves as a direct aftermarket replacement for Mercury OEM part numbers 765-7445T11 and its predecessor, 7445A11.
- Engineered for installation in starboard (right) side cylinders.
- Complete assembly includes new piston rings and a wrist pin.
- Designed for V-6 gasoline outboard engines.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury | 765-7445T11 | Current OEM part number. |
| Mercury | 7445A11 | Superseded by 765-7445T11. |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury/Mercruiser engines, this piston fits select V-6 models. Verify your specific model and that a .030 oversize piston is required before ordering.
| Brand | Model | Rated HP | OEM Part No. | Notes |
|---|---|---|---|---|
| Mercury | V-6 Outboards | 105-Jet | 765-7445T11 | Starboard side |
| Mercury | V-6 Outboards | 135 HP | 765-7445T11 | Starboard side |
| Mercury | V-6 Outboards | 150 HP | 765-7445T11 | Starboard side |
Technical Specs
- Product Type
- Piston Assembly, Starboard .030 Oversize
- Installation
- Starboard (right) side cylinders
- Fuel Type
- Gasoline
- Connection
- Wrist pin (included)
- Included Components
- Includes rings and wrist pin
- Dimensions
- 16.5" H x 9.0" W x 9.0" L
What’s in the Box
- 1 x Piston Assembly - Starboard .030 Oversize (Replaces 765-7445T11)
- 1 x Wrist pin (pre-installed in assembly)
- 1 x Piston ring set (included with assembly)
Installation Notes
- Ensure the engine is off, cool, and disconnected from the battery.
- Drain engine fluids (oil/coolant) as required by your service manual.
- Remove the cylinder head and surrounding components to access the piston.
- Carefully extract the old piston and connecting rod assembly.
- Verify the cylinder has been professionally bored and honed to accept a .030" oversize piston.
- Check and adjust the new piston ring end-gaps according to manufacturer specifications.
- Install the new rings on the piston, correctly oriented.
- Thoroughly lubricate the cylinder wall, piston, and rings with engine assembly lube.
- Install the new piston assembly onto the connecting rod, ensuring correct orientation.
- Reassemble the engine, torquing all fasteners to the specified values.
- Refill with fresh oil and coolant before starting. Follow a proper engine break-in procedure.
Troubleshooting & FAQ
How do I know if this .030 oversize piston is correct for my engine?
This piston is for engines that have had their cylinders bored .030" over the standard size for repair. You must measure your cylinder bore or have a mechanic confirm that an oversize piston is required. Do not install it in a standard-bore cylinder.
Is this piston for the port or starboard side?
This specific part (765-7445T11) is designed exclusively for the starboard (right) side of the engine block. A different part number is required for the port (left) side due to design differences.
Do the included piston rings need to be gapped?
Yes, absolutely. The included piston rings must be gapped according to your engine's service manual specifications before installation. Failure to set the correct gap can lead to poor performance, low compression, or catastrophic engine damage.
What are signs that my old piston needs replacing?
Common symptoms include a noticeable loss of compression, increased oil consumption, blue or white smoke from the exhaust, or a persistent knocking sound from the engine. A definitive diagnosis requires a compression test and internal inspection by a qualified mechanic.
Is there a break-in period for a new piston?
Yes, a proper engine break-in procedure is critical for seating the new rings and ensuring a long service life. Follow the guidelines in your service manual, which typically involves running the engine at varied, moderate RPMs without full load for a set period.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, it is batch-inspected for consistency and quality control.
Shipping speed & cost?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free for most orders; expedited options will appear at checkout where available for your location.
Warranty & returns?
This product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter an issue, contact our support team with your order details. Returns are accepted within our standard window, provided the item is unused and in its original condition. Please see our full policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part before ordering. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
- Professional installation is strongly recommended for safety, proper function, and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — We offer free standard delivery to most regions, with typical transit times of 5–15 days.
- Manufacturer-Direct Value — Our parts deliver fair pricing without compromising on materials or quality control.
Payment & Security
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