Engine Rebuilding

Engine Service is a member of AERA (Automotive Engine Rebuilders Association) and we subscribe to the values and procedures set forth by that organization for proper engine repair and rebuilding by the technical committee.

There is a series of steps that must be taken to properly rebuild an internal combustion engine ( ICE ). This includes SI motors (spark ignition) and CI (compression ignition) motors. These engines come in all shapes and sizes from a 1 cylinder lawn mower to a 16 cylinder monster diesel. Most engines can be successfully rebuilt at a fraction of the cost of a brand new engine especially when you add in the costs of casting blocks, heads, crankshafts, and connecting rods into the equation. The rebuilder typically reuses the original castings and they are re-machined to new tolerances. When putting a piece of equipment back into service whether it be a work truck, a piece of construction equipment, a marine engine, or the family car, it makes economic sense to do it right. It costs less than a new vehicle or equipment, and for the environmental impact, recycling is better than the additional stress of using new resources that have a greater CO2 cost on the environment.

Eventually things wear out. Parts break, loss of power, excessive smoke, funny noises, overheating, loss of oil pressure, steam out the tail pipe, or sometimes, a catastrophic failure and parts flying all over! Time for an overhaul. If any of these symptoms has happened to you, it is a smart move to see if there was a failure in the cooling or oiling system before you put in your fresh remanufactured motor.

Over the last several decades we have worked on hundreds if not thousands of projects, from helping the high school kid and his dad on their first engine project together, to doing engine forensic work for insurance claims, High Performance motors for the local race tracks, restoration projects, from a 1941 V12 Lincoln Zephyr to a 1961 Mercedes Gull wing motor, or our favorite, 60's and 70's muscle cars.

Engine rebuilding should start with a plan and a budget. Expectations sometimes don't match reality.

To begin, the motor must be disassembled, or torn down as we say, cleaned and inspected. This is the point where the expectations sometimes meet reality, especially after a major failure. Inspection and cleaning would include magnafuxing the block and heads on a cast iron engine, vacuum or pressure testing aluminum cylinder heads, straight edging the block deck, the cylinder head fire face, and cam line, and checking the block mainline with a dial bore gauge.

The next step is to determine the machined sizes and make up the parts list. Bearing undersize and piston oversize. After the head is inspected and valve springs checked, a cylinder head list would also be started. Depending on the use of the rebuilt engine, some parts may be reused if there is minimal wear, and to keep the budget from breaking. Close inspection of push rods, rocker arms and shafts, valve springs, retainers, locks, intake and exhaust valves must be OK'd for reuse or be replaced. On high performance or high stress engines, new parts are usually installed. At this point, determination of whether to use upgraded parts can also be made. There are many heavy duty parts available for most engine designs that will improve the performance or life of the engine. Having the engine balanced would be an important extra step to assure a smoother running longer lasting engine.

The block would be bored and finish honed to the next oversize. An option here is using a torque plate to simulate the stress in the cylinder roundness with the head torqued on. Tests have proven horse power gains by the rings sealing better, especially on performance engines.

The basic engine kit would include expansion plugs, full gasket set, pistons, rings, main and rod bearings, cam bearings, thrust washers, timing chain and gear set, camshaft, lifters and an oil pump. These parts will vary depending on engine design and whether you have an overhead cam motor or push rod type.

There are of course many other parts that may be needed in doing an engine rebuild project. To name a few; oil pump pickup, timing tensioner and guides, rocker studs, arms, shafts, valve shims, guides, pin bushings, spacers, speedy sleeves, cylinder sleeves, special lubricants, anti seize, thread lockers, sealants, new fasteners, and etc.

There are also many tools that would also be required, such as a good socket set with ˝" drive deep sockets, as well as a good torque wrench. Some engines require specialty tools such as a torque angle gauge, camshaft locking tools, oil pump primer, engine pre-oiler, and of course an good engine stand. You might want to have a dial indicator with magnetic base to find top dead center, or a micrometer to measure thrust on bearing clearances.

The cylinder head parts list will vary quite a bit as well. After inspection of the valves and other components and a determination of what can or cannot be reused, then the heads would be machined. A close look at the valve guides for wear and then either drill out and install a sleeve type in an integral guide design, or with the later aluminum heads, install a new press in style or re-sleeve the guide that is in the head and ream finish to the proper guide to valve clearance. There are a couple of schools of thought on valve guide stem seal usage. In today's engines there must be a small amount of lubrication left in the valve guide to prevent valve galling and seizing. Older style engines used an umbrella style seal allowing oil splash to lube the valve. As the guide and valve wear, excessive oil consumption and smoking would occur as well as valve to seat run out and a burnt valve. The newer style engines have valve seals attached to the top of the valve guide and some guides have flutes to hold lubrication in the guide. High vacuum and compression engines require close attention to this area. Machining the valve seats correctly and having the proper seated spring pressure is important to valve life. The heat that the exhaust valve sucks up as the hot gasses travel out must be transferred to the cooling system by proper heat transfer from the valve to the cylinder head. This is accomplished by the pressure from the spring holding the valve on to a properly cut or formed seat of the right width cooling the valve head. After the proper specifications are reviewed and the machine work is completed the engine would be ready for final cleaning and assembly.

The engine assembly should also include all critical size inspections and clearances. Proper torque procedures are very important and are readily available. Proper lubrication of installed parts and turning the engine over and checking that everything moves the way it should is of utmost importance. We should now be ready to dress the engine out with the oil pan, front cover, intake and valve covers using the proper sealants and fasteners. This is when replacement of old components with new parts should be considered. A new water pump, thermostat and maybe some sensors or sending units would also be wise. Have the carburetor rebuilt or replaced, the fuel injectors flow tested and cleaned and be sure to inspect that harmonic balancer and flywheel before installing them. The installation and proper break-in is just as critical. Inspect the cooling system, replace worn hoses and belts. Flow test or replace the radiator. Check the motor mounts and cooler lines, the fuel feed lines, the wiring etc. while the engine is out of the vehicle. Replace the filters as required. There is some detailing that could be done in the engine compartment at this time.

Make your list of parts for the installation done when taking the engine out. This will save you many extra trips to our parts department and assure that the correct parts have been ordered ahead of time. Now would be a good time to change that old oxygen sensor as well.

Happy motoring and I hope this helps you think through your next project even if you do it yourself or have us do it in our shop for you.




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