# Overhaul of the Cummins 4BT3.9 Engine > This article provides a detailed description of the verification and overhaul of the Cummins 4BT3.9 diesel engine, which included the regeneration of the crank-piston system, cylinder head, and lubrication system. Discover how our service offerings ensure high performance and reliability of engines in construction machinery. ##### Verification of the Internal Combustion Engine The internal combustion engine **Cummins 4BT3.9**, used in machines such as loaders, dumpers, and wheeled excavators, has come to our service. Our mechanics conducted a thorough verification of the power unit and based on that, we performed an engine overhaul. ##### Reconditioning of the Crankshaft and Piston System The first step in the overhaul process was the reconditioning of the crankshaft and piston system components. **The crankshaft was polished**, and **the connecting rods were completely replaced** with new ones. We used **new pistons with pins**, a complete set of **main and connecting rod bearings**, as well as a **camshaft bearing**. **The engine block** was restored to nominal parameters. ##### Cylinder Head and Timing System **The engine head underwent full reconditioning**, which included planning, replacement of valve guides, valves, and valve seats. **The camshaft was replaced**, which, combined with other new components of the timing system, guarantees precise valve control and optimal engine cycle performance. ##### Lubrication and Cooling System We replaced the **oil pump and water pump with new ones**, ensuring safe operating conditions for the new crankshaft and piston system. Additionally, a **new thermostat and new oil filter** were installed, protecting the engine from overheating and contaminants during the initial phase of operation after the overhaul. ##### Engine Accessories – Reconditioning and Installation As part of the service work, we **reconditioned the turbocharger** and **injector nozzles**, which allows for maintaining the full efficiency of the boost system and ensures proper fuel injection. The replacement of gaskets included a complete set of seals: **timing cover gasket, block cover, oil cooler, oil pickup, and crankshaft seal.** ##### Assembly and Testing of the Engine The engine was professionally assembled by our team, adhering to all service standards. After assembly, it underwent a **test on the engine dynamometer**, during which **stable operating parameters were achieved:** - at 850 rpm – operating temperature 92°C and oil pressure 2.1 bar, - at 2500 rpm – constant power 100 HP, peak power 117 HP. The tests confirmed **very good condition of the unit** and **effectiveness of the repair work performed**. The engine started without any issues and is ready for further operation. ##### Cummins Construction Machinery Service – Warranty and Support The **Cummins 4BT3.9** engine after the overhaul is covered by a warranty. Our specialists recommend a **check-up after 50 operating hours**, which includes not only filter replacement but also inspection of all connections and any potential leaks. We also offer **full service for construction machinery and Cummins diesel engine service** – both at our facility and as part of **mobile service**. Cummins 4BT3.9 engines are used in a wide range of machines. Example machines: Case 580 Super L, JCB 3CX, Bobcat 873, Hyundai R55-7, Hitachi EX60, Komatsu FG25T-16, Ingersoll Rand VR-90, Genie S-65, Terex TX760, Takeuchi TB175, New Holland LB75, Skyjack SJ8841, Clark C500-Y80, Dynapac CA152, Hamm HD10, Vermeer V8550, Ditch Witch RT115, Bomag BW120, Volvo EC35, Grove RT530C, Yale GDP080, Manitou MT 932, LiuGong 835H, TCM FD30 Published: 2025-08-04 --- Source: https://wibako.com/about-us/news/316-overhaul-of-the-cummins-4bt3-9-engine Contact: +48338704200, biuro@wibako.pl