DIESEL Tech Solutions Guide 2013
A Brief Overview of Pistons: Although several differCaterpillar C7 Engines ent piston part numbers are used in This popular engine was released in these engines, two distinct design 2003, and now has a total producdifferences are important to note. tion of over 300,000 units. With a Depending on the application, the range from 190hp to 360hp, this engine may have aluminum or steel mid-range six cylinder engine is (one-piece) pistons. The one-piece very versatile (Figure 1). This popular engine can often be found in on-highway trucks, and also in off-highway applications such as loaders, skidders, excavators, motor graders, and industrial and marine units. It is actually a 7.2 liter (439 cid) engine with a 4.33˝ bore (110mm) and 5.0˝ stroke (127mm). Cylinder Head: The single cylinder head is similar to the late 3126B heads, with 3 valves per cylinder (1 exhaust valve & 2 intake Fig. 1 The Cat C7 has a range valves). The electronically from 190hp to 360hp and is a actuated injectors are losteel piston very versatile engine. cated between the three design is valves. A common push produced by rod and rocker arm design operates inertia/friction welding a steel the valves, driven from a camshaft crown to a steel piston skirt. This located in the cylinder block. The design creates a piston with an inhead is a cross flow design, with the ternal oil cooling gallery in the intake ports located on the left side, crown, and increased structural and the exhaust ports on the right. strength and resistance to fatigue. Cylinder Block: The cylinder Gear Train: The front gear train block has “parent” bore cylinders, drives the camshaft, oil pump, acmeaning it does not have replacecessory drives, and the high presable liners, but the cylinders can be sure fuel pump for the common rail sleeved if necessary. Before boring fuel system. the cylinder block to accept repair Fuel System: The common rail sleeves, follow the OE guidelines to fuel system operates under extreme ensure that the block is salvageable. pressure. The transfer pump that One guideline in particular explains that the cylinder block should be measured with a digital disc brake caliper to determine if the cylinder wall thickness is thick enough to accept a cylinder repair sleeve. Insert the thinner leg of the caliper approximately 1.25˝ into the water passage at the front between of each cylinder. The block must be a minimum of 0.170˝ (4.3mm) for Fig. 2-3 CAT 3114, 3116 and 3126 the block to be salvageable. The use engines may require oversize head of a stress plate is also recomgaskets. Use the chart on the right mended for measuring & honing to determine the correct gasket. the cylinder diameters. 20 February 2013 | EngineBuilder Tech Solutions Guide
draws fuel from the fuel tank and supplies the fuel pump, produces 280 psi (+/- 15psi). The high pressure fuel pump delivers fuel to the fuel rail at approximately 27,500 psi, and supplies the hydraulic electronic injectors. Overall, C7 engines are growing in popularity within the rebuilding or repair markets. Determining the Correct Head Gasket on Cat 3114, 3116 & 3126 Engines While other engine manufacturers have utilized thicker head gaskets to help salvage cylinder blocks they are not so common to Caterpillar engines. Oversized head gaskets may not be something you would normally think about when repairing or rebuilding a Caterpillar engine. As the 3114, 3116 and 3126 (2valve) engines age you may encounter engines that have or will require thicker (oversized) head gaskets. IPD says it does not yet offer these oversized head gaskets at the time of publication, but their intent for this bulletin is to help inform you of issues within the engine ranges of their products. Items that could cause issues include the block deck surface to crankshaft center line measurements decreasing due to machining of the deck or the line bore of bearing journals. Be aware that the last