Getting my hands dirty

Taking on engine work


I have a new found respect and appreciation for professional vehicle technicians, especially for those that possess the ability to diagnose the source of a problem quickly and accurately.  This comes from my participation in a hands-on engine tear-down and rebuild at Peterbilt's Training Center in Denton, TX.  I was invited by Peterbilt to participate in a training session on Paccar's new heavy duty MX engine, which was launched in January.  The Paccar MX is in-line 6-cylinder, 4 valves per cylinder, 12.9-liter engine that comes standard with an integral engine compression brake. The engine uses selective catalytic reduction (SCR) in combination with exhaust gas recirculation (EGR).  My training session was a special condensed version of the hands-on engine training that all Peterbilt and Kenworth dealer salespeople and technicians are receiving on the new engine.  The five days of training for the technicians is designed to help them better understand the design elements and features that make the MX engine durable and reliable. The Paccar MX has a B10 engine life of 1 million miles, meaning 90 percent of the engines will reach that mileage.  During their three days of hands-on training, the truck salespeople learn how to spec an engine into a customer's application for both fuel economy and performance.  Prior to my training, I had the opportunity to drive a variety of Peterbilt tractors with MX engines, each with different horsepower ratings and each coupled to a loaded trailer.  I found the engines had responsive feel and power. I noticed significantly reduced vibration, lower in-cab noise levels and less engine noise outside the cab.  Before getting to work on the MX engine I received an overview of the general specs and chief features of the MX engine. Key among them:  - Block and cylinder head manufactured with high-strength compacted graphite iron, a premium material that is 75 percent stronger and 20 percent lighter than conventional grey iron, resulting in superior power-to-weight performance.  - A single camshaft with no counterweight for a more simplified and 25-pound lighter design. This reduces weight and increases power for quicker acceleration and smoother overall operation.  - Fractured cap technology for connecting rods and main bearing caps. This technology virtually eliminates cap shift and results in greater strength and contributes to longer power and torque curves along a wide rpm range.  - Electrical systems designed to provide increased reliability through the use of sealed connectors and an air-cooled ECM. A fully encapsulated wiring harness mounted directly to the block to protect wiring from the elements and remove stress from connectors for a more dependable electrical system that is serviced in a non-invasive manner.  The first portion of my get-dirty training included disassembling the oil pan, oil pump, stiffener plate and main bearing. If that wasn't challenging enough for me, it all had to be reassembled.  I am happy to report that with occasion guidance of Peterbilt service and training personnel, the engine did get put back together, although it was a couple of bolts shy. (Good thing this engine wasn't going back into service.)  Looking over the "rebuilt" engine, one of the service trainers remarked: "I wouldn't give up your day job."  Next was disassembly and reassembly of the valve cover, rocker assembly, high-pressure fuel system and engine brake and pump module. Here again, I managed this - with help, and again, somehow misplaced a few bolts.  I should note that all this engine work was done with a "clean" engine in an engine lab. The engine was mounted on a stand that allowed the engine to be rotated.  Consequently, there was no need to climb around or under the engine, and access to all components was effortless. I remained relatively clean.  As I was doing my engine work, I realized even more clearly just how difficult a technician's job is, and how knowledgeable, skilled and talented technicians need to be to properly inspect, maintain and repair vehicles.  I tip my hat to all professional truck technicians.