TrackTech Connecting Rod Bolt Set
March 28, 2025

What is the Purpose of Connecting Rod Bolts for Diesel Engine Trucks?

Written By: TRACKTECH FASTENERS

Each part of the truck with a diesel engine plays a vital role in achieving peak performance and durability. One important component is connecting rod bolts. These comparatively minute yet critical fasteners keep the engine’s connecting rods intact. The connecting rods, connecting the pistons with the crankshaft, are exposed to the utmost stress and pressure during engine operation.

The connecting rod bolts must maintain a firm, stable connection to keep the engine running consistently and efficiently. Without them, the high-strength forces acting within a diesel engine might be catastrophic, ultimately halting the entire engine’s operation. Below, we’ll discuss the function and necessity of connecting rod bolts within diesel engine trucks and why these bolts are never optional for the engine’s function.

What is a Connecting Rod Bolt?

The connecting rod bolt is a dedicated fastener that fits between the connecting rod and the crankshaft to fasten the connecting rod to the crankshaft in an internal combustion engine. The connecting rod plays a crucial function by connecting the piston to the crankshaft, translating the linear motion of the piston to rotational motion that propels the vehicle. To make this vital bond strong and consistent, connecting rod bolts attach the connecting rod to the crankshaft, and occasionally to the piston.

The bolts are designed to endure extremely high stress, tension, and pressure levels. Once an engine runs, it creates huge forces due to combustion, which are transmitted through the connecting rod. These forces act upon the bolts and must be robust and resilient enough not to fail. Failure of a connecting rod bolt could result in severe damage to the engine and lead to disastrous mechanical failure.

The bolts usually consist of high-strength materials such as steel or alloy and are also made to resist fatigue, stretching, and corrosion. Careful torque settings are very important when mounting connecting rod bolts since a wrong tension will cause either bolt failure or a lack of pressure, endangering engine damage. Some engines utilize stretch bolts, which are torqued to a particular elongation point to have a correct fit and ideal tension.

What is the Purpose of Connecting Rod Bolts?

Here’s the purpose of connecting rod bolts:

Secure Connection: They secure the connecting rod to the crankshaft or piston, making it firm and stable.

Force Transfer: They facilitate the effective transfer of forces produced due to combustion from the piston to the crankshaft.

Prevent Movement: Keep the connecting rod in position and prevent it from moving or disconnecting under high pressure and tension during engine run.

Durability: Made to endure severe stresses, tension, and pressure under engine cycles.

Engine Efficiency: They ensure the correct alignment of engine parts, leading to smooth operation and efficiency.

Engine Protection: Protect against mechanical failure by keeping the connecting rod firmly in place, preventing devastating damage.

Longevity: Connecting rod bolts prolong the engine’s life and reliability by tightly bonding all pieces.

What Truck Models Use CRBs?

Connecting Rod Bolts (CRBs) are utilized in nearly all diesel engine trucks since they are essential to holding the connecting rods in place against the crankshaft. Although almost any truck with an internal combustion engine utilizes CRBs, specific models usually depend on the engine type and manufacturer. Specific popular truck models and their respective engine types that utilize connecting rod bolts are:

Duramax Engines (Chevrolet/GMC)

Powerstroke Engines (Ford)

  • Ford’s 6.7L Powerstroke V8 Diesel engine and earlier versions like the 6.4L and 6.0L.

Cummins Engines

Ford Super Duty Trucks

  • Engines like the 6.7L Power Stroke V8 Diesel use connecting rod bolts to secure the connecting rods to the crankshaft.

Ram 2500/3500

  • These trucks, equipped with the 6.6L Duramax Diesel engine, also employ connecting rod bolts for engine integrity.

Freightliner Cascadia

  • Heavy-duty trucks such as the Freightliner Cascadia, powered by various Detroit Diesel or Cummins engines, also use CRBs.

International LoneStar

  • International trucks with N13 or Cummins engines rely on connecting rod bolts to secure the engine components.

Mack Granite

  • Mack trucks with MP8 engines incorporate CRBs to secure the engine’s connecting rods.

Mack Granite

  • Mack trucks with MP8 engines incorporate CRBs to secure the engine’s connecting rods.

Kenworth T680

  • The Kenworth T680, often powered by PACCAR or Cummins engines, also uses connecting rod bolts.

Conclusion

Connecting rod bolts (CRBs) are essential elements within diesel engine trucks, preventing the connecting rods from detaching from the crankshaft. Within Duramax, Powerstroke, or Cummins engines, CRBs assist in transferring combustion forces for efficient functioning, avoiding engine malfunction, and guaranteeing smooth operation. CRBs play a central part in engine function, durability, and lifespan, and are essential elements in trucks spanning light-duty trucks to heavy-duty trucks. Awareness of their significance promotes maximum engine condition and reliability when used for prolonged periods.

FAQs

A torque wrench is the desired tool for tightening connecting rod cap bolts. It ensures the bolts are tightened to the manufacturer’s specified torque value for optimal performance and safety.

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