The Three stages of engine woes: Repair Rebuild or (buy) reman
So your engine has some issues. Depending on the severity, how do you know if it’s just a matter of repairing it, if it’s time for a rebuild, or if a remanufactured engine is the way to go?

By Paul Abelson, senior technical editor

Sooner or later, something in your engine is going to wear out or break. Any machine with hundreds of moving parts will wear. It may be something simple like a broken valve spring or a worn water pump. Those problems require simple fixes like parts replacement. It could be more involved, with multiple symptoms and multiple causes. High oil consumption, for example, may be from leaking oil seals, worn valve guides, scored cylinder liners, worn piston rings or more. But these are repairable.

When something goes wrong, your choices fall into one of three categories, the three Rs of maintenance: Repaired, Rebuilt or Remanufactured. They are increasingly more costly, but with increased costs come increased effectiveness and future engine life. So which option should you choose? Before considering decision-making criteria, let’s define these terms.

Repair refers to correcting one thing or one set of things. For instance, when the engine starts running hotter than usual, you check your thermostat, hoses and water pump. When you discover a damaged part, you replace it. You have focused on a specific problem, identified its cause, and corrected it. That is a repair.

With the one broken valve spring, replace all the valve springs. When one is broken, others are probably weak and near failure. Since much of the labor is done, it is cost-effective to replace them all. The same holds true for injectors, valves and any multiple parts. But these are still repairs.

A rebuild is when a shop or dealer disassembles the engine. This used to be a common practice into the 1980s. When engines began losing power, burning oil and burning more fuel, it was time for a rebuild. It could be done with the short block (the engine with the cylinder head and accessories removed) left in the frame – called an “in-frame” – or with the entire engine removed to an engine stand or workbench, often called an “overhaul.”

When an engine is rebuilt, all known wear parts are examined. How thoroughly and to what level of detail depends on the shop’s practices. Generally, all bearings and piston rings are replaced with new or reconditioned parts. Worn bearings are easy to identify, from scoring and copper showing through the lead alloy face.

But what about camshafts and cam bushings? Twenty years ago, tolerances were generally 10 to 15 one-thousandths of an inch (0.010” to 0.015”). Today, thanks to better manufacturing practices and materials, they are now three one-thousandths or less (0.003”). Will the rebuilder use a micrometer on every lobe? Will he measure every bearing journal across multiple diameters? Again, that depends on shop practices and technician skill.

Remanufacture is a more involved process designed to bring engines back to original specifications or better. For example, a 2006 engine may have been built originally with a certain material for the water pump seal and another material in the belt tensioner. After it left the factory, newer materials with greater durability or less friction were developed. When you buy a remanufactured engine, you get those latest materials.

With repair and rebuilding, you keep the same engine. A remanufactured engine comes in a crate and is treated like a new, factory-built engine, which essentially it is. Your engine is taken in as a core exchange, to be remanufactured for someone else.

Your old engine goes to the re-man facility where it is completely disassembled. The block and heads are thoroughly inspected for cracks and excess wear. Cracks are welded using the latest technology. Wear beyond allowable new product tolerances is repaired through metallization, a process of high-temperature plasma spraying new metal to build up surfaces, followed by machining to new tolerances.

All moving parts subject to wear are examined and usually refurbished. After quality control, all parts go into the remanufacture “parts bin.” Even bolts and studs can be discarded and replaced if newer metallurgy or thread design has superseded an older design or if they have been over-torqued during repairs.

A rebuild involves discretion about what parts are saved, which opens the door to the possibility of human error in that process. With a remanufacture, all parts are new or like new. Even more importantly, all assembly is conducted under factory conditions, especially torque application. As with a new engine, fasteners are torqued with DC electric tools so values can be recorded in case problems arise.

With a factory remanufactured engine, you get new belts and hoses, and often a new fan and fan drive, new radiator and a new clutch. But not all remanufactured engines come from engine makers’ factories. Companies like Jasper Engines built their reputation using factory procedures and offering competitive warranties.

Not all remanufacture needs to be done at an engine factory. Caterpillar distributors, for example, are trained and equipped to remanufacture their engines using factory parts and procedures. This keeps their distributors in the on-highway truck market. Distributor remanufacture may take a few days longer than replacing an engine, but many Cat distributors maintain engines in inventory for that purpose.

Remanufactured engines are ecologically and economically friendly, incorporating the latest emissions controls and delivering the best fuel mileage seen in years. Warranties are similar to those of new trucks. As long as your truck has life in it, a remanufactured engine may be your best bet. And when you finally wear out your truck, your engine can be the basis for a glider kit.

For minor, easily identified problems, have a repair done. If your cab, chassis and suspension are in good shape but your engine is out of warranty and wearing, consider a remanufactured engine. A rebuild is less expensive up-front, but remanufactured engines can be pre-ordered and exchanged in two to three days. A rebuild may take 10 to 14 days. Can you afford that much downtime? LL