Editorial: How to choose an engine machine shop

When a customer’s engine needs to be rebuilt or replaced, you may wish to farm this out if your shop isn’t equipped or staffed for in-depth engine rebuilding. Of course, if you opt for an engine replacement and decide to go with a new or reman factory engine, this will likely include a limited warranty. In this case, your shop will be able to simply remove the bad engine and install the fresh unit. However, if the original engine is to be rebuilt, or if the customer opts to buy a salvage used engine, the services offered by a local engine machine shop may be in order.

A skilled engine machine shop will be able to perform disassembly, component cleaning, testing for cracks, cylinder wall thickness and condition, deck straightness, leak-testing for cylinder heads, cylinder head reconditioning (decks, valves, valve seats, value guides, etc.), crankshaft journal condition, connecting rod condition, piston condition, etc. Any flaws can be corrected (where feasible), and it of course includes engine assembly. The majority of this involves equipment (and experienced machinists) that your shop likely is not equipped to provide.

When choosing an engine machine shop, the shop should offer the following services:

• Crack detection equipment (magnetic particle and dye penetrant)
• Cleaning equipment including a jet wash, oven, shot blaster and block tumbler
• Resurfacing machine — for heads and blocks
• Seat and guide machine — for cylinder heads
• Vacuum tester — for cylinder heads
• Ultrasonic cylinder wall thickness equipment
• Cylinder boring equipment
• Cylinder honing station
• Block main bore honing station
• Crankshaft grinder
• Crankshaft polisher
• Connecting rod hone
• Connecting rod heater — for servicing piston to rod interference pin fit
• Connecting rod straightness checker
• Valve spring tester
• Cylinder head pressure testing machine
• Crankshaft/rotating assembly balancing equipment
• Engine live-fire stand

Keep in mind that it is common for some machine shops to farm out crankshaft grinding to a specialty company due to the size and expense of a quality crank grinder. Not all engine rebuilder machine shops have the space for this equipment.

Whether the engine is to be rebuilt or replaced with a used engine, your local engine machine shop should offer live-fire engine testing, via either an engine dyno or a live-fire test stand. This allows the engine to be run and verified for proper operation including oil pressure, coolant temperature, vacuum leaks, and throttle response, verifying that the engine runs and functions properly. If a problem exists, it’s easier to take care of it now, before you go to the trouble of installing the engine.

While most shops may have a live-fire stand, some shops will offer engine dynamometer services. An engine dyno is typically used by high performance shops that build race engines. Even though you may not be concerned about horsepower and torque data, if a live-fire test stand is not available, dyno testing (while more expensive) provides an option to verify engine function. In general, using a live-fire test stand may cost in the neighborhood of $200 to $500, while a dyno session (obviously overkill, expense-wise) can easily run in the range of $1,000 or more. Having the engine run before you install it eliminates the worry of finding out there’s a problem only after spending hours installing the engine. That can really ruin your day.