Connecting Rod Bearing Kit – Fits Volvo Penta MD21/AQD21 Diesel Engines (Replaces 875303)
Connecting Rod Bearing Kit – Fits Volvo Penta MD21/AQD21 Diesel Engines (Replaces 875303) is backordered and will ship as soon as it is back in stock.
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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 is a standard size Connecting Rod Bearing Kit designed for Volvo Penta diesel engines, including models MD21A, MD21B, AQD21A, and AQD21B. It provides a precise fit for restoring engine performance and reliability.
This kit serves as a direct replacement for Volvo Penta OEM part 875303 and other aftermarket equivalents.
- Engineered for standard size crankshaft journal specifications.
- An oversized version (0.10 mm) is also available for machined crankshafts.
- Designed for use in marine diesel engine environments.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Volvo Penta | 875303 |
| Aftermarket | REC875303 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Engine Type | Stroke | OEM Part No. |
|---|---|---|---|---|
| Volvo Penta | MD21A | Diesel | 4-Stroke | 875303 |
| Volvo Penta | MD21B | Diesel | 4-Stroke | 875303 |
| Volvo Penta | AQD21A | Diesel | 4-Stroke | 875303 |
| Volvo Penta | AQD21B | Diesel | 4-Stroke | 875303 |
Technical Specs
- Product Type
- Connecting Rod Bearing Kit
- Application
- Diesel Engines
- Dimensions
- Height: 3.0 cm, Width: 7.0 cm, Length: 16.0 cm
- Weight
- 0.27 kg (0.59 lb)
- Size
- Standard
What’s in the Box
- Connecting Rod Bearing Set (replaces 875303)
Installation Notes
- Disconnect the battery and safely drain all engine oil and coolant.
- Access the engine's bottom end by removing the oil pan and any obstructions.
- Identify and mark the connecting rod cap to ensure correct orientation upon reassembly.
- Carefully remove the connecting rod cap bolts and the cap. Keep paired bolts with their caps.
- Remove the old bearing shells from both the connecting rod and the cap.
- Thoroughly clean the rod, cap, and crankshaft journal surfaces. Ensure they are free of oil and debris.
- Apply a quality assembly lube to the new bearing shells before installation.
- Install the new bearing shells, ensuring the locating tangs are correctly seated in their notches.
- Reinstall the connecting rod cap and torque the bolts to the manufacturer's specified value and sequence using a calibrated torque wrench.
- Verify oil clearance using Plastigage as recommended in your engine's service manual.
- Once all bearings are installed and checked, reinstall the oil pan with a new gasket.
- Refill the engine with the correct grade of oil and coolant, then reconnect the battery and check for leaks after starting.
Troubleshooting & FAQ
How do I know if I need a standard or oversized bearing kit?
This kit is for standard-size crankshafts. If your crankshaft has been machined (ground) to correct for wear, you will need an oversized bearing. Consult your engine technician or measure the crankshaft journals with a micrometer to determine the correct size needed.
What are the signs of a failing connecting rod bearing?
Common symptoms include a persistent, rhythmic knocking or ticking sound from the engine that increases with RPM, low oil pressure, and the presence of metallic particles in the engine oil during an oil change.
Can I replace just one connecting rod bearing?
While possible, it is highly recommended to replace all connecting rod bearings at the same time. This ensures consistent clearances, wear patterns, and engine balance for long-term reliability.
Is assembly lube necessary for installation?
Yes, absolutely. Assembly lube is critical to protect the bearings and crankshaft from scoring and damage during the initial engine startup before normal oil pressure is established.
What is the expected lifespan of these bearings?
With proper installation and regular engine maintenance (including clean oil and correct operating temperatures), aftermarket bearings should meet or exceed the lifespan of the original OEM parts, which can be thousands of hours of operation.
Will this kit fit engine models that are not on the compatibility list?
We can only guarantee fitment for the models listed. Using this kit on other engines is not recommended, as even minor differences in specification can lead to catastrophic engine failure. Always verify your part number.
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
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