Cummins NH855 Engine Parts – Connecting Rods & Related Components

The Cummins NH855 engine, part of the iconic Cummins Big Cam and Small Cam engine families, has earned a reputation for long-term durability in both industrial and marine applications. To keep these engines running at peak performance, proper maintenance of the connecting rods and associated components is essential. Connecting rods are the critical link between the pistons and the crankshaft, transmitting combustion power into rotational force. Over time, wear on bearings, bushings, and rod assemblies can compromise engine efficiency and lead to serious damage if not addressed.

At Diesel Pro Power, we provide a complete catalog of Cummins NH855 connecting rod parts, including bearing sets in multiple sizes and connecting rod bushings. With over 40,000 satisfied customers worldwide, we make it simple to find, order, and install the parts you need with confidence.

Connecting Rod Bearings for Cummins NH855

Connecting rod bearings serve as the replaceable wear surface between the connecting rod and the crankshaft journal. By absorbing friction and maintaining oil clearance, they protect both the rod and crankshaft from damage. For the NH855, bearings are available for both Small Cam and Big Cam versions of the engine, and in different thicknesses depending on your rebuild needs.

Bearing Sets for Cummins NH855 Small Cam Engines

• Standard Size Bearings
  These are used when crankshaft journals are still within factory specifications. They ensure proper oil clearance and long service life without requiring any grinding or machining of the crankshaft.

• 0.010” Oversize Bearings
  When crankshaft journals have been ground undersize during a rebuild, 0.010" oversize bearings restore proper fit and oil clearance. This size is commonly used during the first reconditioning.

• 0.020” Oversize Bearings
  For crankshafts that have undergone further machining, 0.020" oversize bearings compensate for the additional reduction in journal diameter. These allow engines to remain serviceable without replacing the crankshaft.

Each bearing set for the NH855 Small Cam consists of an upper and lower shell to service a single connecting rod.

Bearing Sets for Cummins NH855 Big Cam and NT855 Engines

The NH855 Big Cam shares many components with the NT855, including connecting rod bearings. These bearings are available in the same sizes as the Small Cam versions:

• Standard Size Bearings

• 0.010” Oversize Bearings

• 0.020” Oversize Bearings

Like their Small Cam counterparts, these bearing sets include the upper and lower halves for servicing one rod. Choosing the correct size ensures optimal oil film, reduces friction, and prevents catastrophic bearing failure.

Connecting Rod Bushing for Cummins NH855

The connecting rod bushing supports the piston pin (also called the wrist pin), allowing the piston to pivot smoothly within the rod. Over time, this bushing can wear out due to high loads and constant motion. Replacement is critical during any major engine overhaul, especially if pistons or piston pins are being renewed.

• Piston Pin Bushing
  Designed to press into the small end of the connecting rod, this component ensures precise fit and reduces wear on the piston pin. A properly installed and lubricated bushing maintains correct piston alignment, preventing premature piston skirt or liner damage.

Why Replace Connecting Rod Bearings and Bushings?

• Prevent Bearing Seizure – Worn bearings can lose their oil film, causing metal-to-metal contact that can damage the crankshaft.

• Restore Oil Clearance – Bearings and bushings maintain the precise tolerances required for oil lubrication. Oversized bearings are designed to match machined crankshafts and keep oil flow within specifications.

• Extend Engine Life – Fresh bearings and bushings reduce internal friction, lower operating temperatures, and prevent catastrophic failure.

• Support Heavy-Duty Loads – The Cummins NH855 is often used in demanding environments. Strong, properly fitted connecting rod parts help it withstand continuous operation under load.

Tips for Choosing the Right Connecting Rod Parts

1. Identify Engine Version – The NH855 exists in both Small Cam and Big Cam versions. Bearing sets are specific to each design, so selecting the correct type is crucial.

2. Check Journal Size – Use micrometers to measure crankshaft journals. If they have been ground undersize, select the matching oversize bearings (0.010”, 0.020”, etc.).

3. Replace Bushings During Rebuilds – Even if the connecting rod bushing shows minimal wear, replacement is recommended whenever pistons are removed. This ensures the piston pin runs on a fresh, smooth surface.

4. Replace in Sets – While individual bearing sets service one rod, it is generally best practice to replace all connecting rod bearings during a rebuild for balanced performance.

Diesel Pro Power Advantage

When you order Cummins NH855 connecting rod bearings and bushings from Diesel Pro Power, you benefit from:

• Worldwide Shipping – We deliver parts quickly to customers around the globe.

• Proven Reliability – Trusted by more than 40,000 satisfied customers.

• Simple Online Ordering – User-friendly catalog with detailed part categories.

• Guaranteed Fit – All parts are designed for direct compatibility with Cummins NH855 engines.