Crankshaft Bearing Kit – Fits MerCruiser 454 MKI (Replaces 13021/23-818476)
Crankshaft Bearing Kit – Fits MerCruiser 454 MKI (Replaces 13021/23-818476) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
Worry-free returns
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.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
This Crankshaft Bearing Kit – Fits MerCruiser 454 MKI (Replaces 13021/23-818476) is engineered for MerCruiser 454 7.4L V8 engines produced between 1983 and 1988. It is designed specifically for MKI generation big block motors that require 0.010" oversized bearings, typically after a crankshaft has been machined or has worn beyond standard specifications.
It serves as a direct replacement for MerCruiser part 13021 and Mercury numbers 23-818476, 23-818476001, and 23-8M0030982, along with the Felpro equivalent REC13021.
- Installation: Mounts as an internal engine component.
- Sizing: Provides a 0.010" (0.254 mm) oversize to compensate for worn crankshaft journals.
- Construction: Made with a durable steel backing and a precision metal alloy overlay for reliable performance.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| MerCruiser | 13021 |
| Mercury | 23-818476 |
| Mercury | 23-818476001 |
| Mercury | 23-8M0030982 |
| Felpro | REC13021 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This part is designed exclusively for the MerCruiser engine models listed.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | 454 MKI (Gen IV) | 330 | 4-Stroke | 1983–1988 | 13021/23-818476 | 0.010" oversized |
Technical Specs
- Product Type
- Crankshaft Bearing Kit (0.010" Oversized)
- Installation
- Engine Internal Component
- Housing Material
- Steel backing with precision metal alloy overlay
- Dimensions
- L: 210 mm (8.27") × W: 145 mm (5.71") × H: 60 mm (2.36")
- Weight
- 0.72 kg (1.59 lbs)
- Operating Temperature
- Engine operating temperature range
- Warranty
- Manufacturer standard warranty
- Other Technical Attributes
- 0.010" (0.254 mm) oversized bearings for worn crankshafts
What’s in the Box
- Complete bearing set supplied as a single assembly.
Installation Notes
- Thoroughly clean the engine block, main caps, and crankshaft of all oil, debris, and old bearing material.
- Verify the crankshaft main journal diameters with a micrometer to confirm they are machined for 0.010" oversized bearings.
- Install the upper bearing halves into their respective saddles in the engine block, ensuring the locking tangs are correctly seated.
- Install the lower bearing halves into the main bearing caps.
- Apply a generous amount of high-quality engine assembly lube to all bearing surfaces and crankshaft journals.
- Carefully lower the crankshaft into place onto the upper main bearings.
- Install the main caps with their bearings and torque the bolts to the engine manufacturer's specified sequence and values.
- Check for smooth crankshaft rotation by hand after torquing the caps. Resistance may indicate an issue with clearance or alignment.
Troubleshooting & FAQ
How do I know if I need 0.010" oversized bearings?
Oversized bearings are required when a crankshaft has been machined (ground down) to restore a smooth, round surface. You must measure your crankshaft's main journals with a micrometer. If they have been machined to be 0.010" smaller than the standard factory diameter, this kit is the correct size.
Will this kit fit a Gen V or Gen VI 454 engine?
No. This bearing kit is specifically designed for the MerCruiser 454 MKI (Gen IV) engine models from 1983–1988. Later generations have different specifications.
What are the signs of a failing crankshaft bearing?
Common symptoms include a deep knocking, rumbling, or pounding sound from the engine's lower end that often increases with RPM. Other signs are low oil pressure readings, a flickering oil pressure light, and the presence of metallic flakes or "glitter" in the engine oil during an oil change.
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 vs 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.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
