Most recently, a technician friend was telling me about an incident he experienced with the form, fit and function of aftermarket replacement parts. Generally, the conversation has to do with the poor quality of many offshore manufactured parts that cross the counters of several major programmed parts distributors. In this case, the combined inadequacies or failures of each component on an engine installation formed what might be called a “perfect storm” of form, fit and function events.
In short, the tech had installed a locally remanufactured in-line six cylinder engine in a classic 1970s Toyota Land Cruiser. A few days after the vehicle was released to the customer, the customer reported that he had a green liquid leaking on his garage floor at the centerline of the engine. As might be suspected, the tech told the customer to return the vehicle immediately. Unfortunately, the engine stalled on the way to the shop with only 30 miles of running time on the odometer. It goes without saying that the customer was exceedingly disappointed with his expensive, newly rebuilt Toyota engine.
During the “post-mortem” inspection, the tech found that the leaking liquid was coming from a seemingly innocuous rubber coolant outlet block-off cap that he had installed on the new coolant pump he had recommended to his customer. The aftermarket water pump was designed to fit multiple applications, so the rubber hose cap was used to cap off an extra coolant outlet. Because a poor grade of rubber was used to mold the hose cap, the hose clamp used to secure the cap in place had split the cap at the point of contact.
As for the engine stalling on the way back to the shop, my mechanic friend discovered that all six exhaust valves had stuck open, causing a simultaneous loss of compression on all cylinders. After calling his rebuilder, he discovered that his normally reliable engine machinist had switched from the OE steel valve guides to bronze guides that promised higher longevity at less cost to the customer. Although the exhaust valves were installed at the normal .0015-inch valve-to-guide clearance, the new guides extended slightly farther into the exhaust port than the OE.
Needless to say, the above incident involved parts with the “Made in China” label. China has recently provided a lot of fodder for newscasters by manufacturing everything from poisonous dog food to toys with lead-laced paint jobs. Even as the alarm sounds however, form, fit and function isn’t about parts made in China. Rather, form, fit and function is about parts that perform with the same or better accuracy and longevity as Original Equipment Manufacturer designs.
THE INTERNATIONAL SHELL GAME
Let’s face it: We’re now living in a world economy. The days are gone when each item we picked up at the local grocery or hardware store has the “Made in USA” label molded or stamped in place. During the 1950s, “Made in Japan” was the object of ridicule because post-war Japan was getting its economy up and running by making toys from tin cans and bamboo sticks to market in the United States. As a young boy, I recall getting metal toys that actually had a can label printed on the underside. Of course, “Made in Japan” now has become a stamp of quality, from the expensive digital camera I bought last year to the hybrid vehicles that many of us are driving today.
Today’s economy is much more complex than post-World War II. We now buy auto parts, various components of which are made in numerous overseas countries and assembled in Canada, Mexico or the United States. A brand new “Made in the USA” domestic vehicle will arrive on the showroom floor with components made in countries like Japan, China, Israel and Indonesia. The world economy is the trend of the future and nothing on the horizon will reverse what we’re seeing now on aftermarket parts shelves and under the hoods of our latest automotive marvels.
THE COSTS OF FORM, FIT AND FUNCTION FAILURES
Whoever said that time is money nailed the essential truth of the modern production automotive repair shop. In my opening example, the form of the coolant pump was at fault because it had an extra coolant outlet that needed to be capped with a non-OE part. Next, the rubber cap did not function as intended because it couldn’t withstand the heat of the coolant and the pressure of the hose clamp beyond the first warm-up cycle. Last, the aftermarket valve guides didn’t function as designed because they weren’t dimensionally correct and the “bronze” material that they were made from might not have been compatible with the steel valve stems. The result of this “perfect storm” of form, fit and function was an expensive comeback for the machinist who rebuilt the cylinder head and the mechanic who installed the rebuilt engine.
Although the wholesale cost of the parts is relatively insignificant, the costs to the machinist and mechanic destroyed the profit initially realized in the long, hard hours spent rebuilding and replacing the engine. In addition, the machinist suspected that the valve guide failure might have been caused by an overheating condition caused by a loss of coolant. He responded by replacing the valve guides, but withholding warranty labor for replacing the cylinder head. The only saving factor for the installer was that the valve guides failed before the defective rubber cap had leaked enough coolant to ruin the engine.
MODERN VEHICLE TECHNOLOGY
According to my experience, the most common failures of form, fit and function occur in vehicle-specific components like spark plugs, spark plug wires and brake friction. Although spark plugs aren’t normally considered to have form, fit and function problems, let’s look a little closer.
There are huge form, fit and function differences between a spark plug that’s designed to last 20,000 miles and one designed to last 100,000 miles. The former is made with a cheap steel shell and steel electrodes. The latter is made with a plated steel shell and plated electrodes. The former may seize in the cylinder head and ruin the spark plug threads while the latter can be removed 100,000 miles later with no damage to the cylinder head. If either is a non-OE spark plug, the heat range and electrode projection into the combustion chamber might deviate from OE specification. If, for example, the spark plug has a single, instead of a dual electrode, it might cause a P0300 misfire trouble code and illuminate the Malfunction Indicator or Check Engine warning light. Enough said about the form, fit and function of spark plugs.
Like the spark plug, spark plug wires must last at least 100,000 miles. Form is especially important, because the spark plug, coil boots and terminal connectors on modern wires are very application-specific. As to function, low-quality wires can leak high secondary ignition voltages to ground and cause cylinder misfires that will ruin the vehicle’s expensive catalytic converters. In regard to fit, suffice it to say that each “universal” set of spark plug wires always has several wires too long and several too short to fit in the OE plug wire looms. The premium custom set, on the other hand, has the form, fit and function needed for easy installation and long-term reliability.
Last, while the form of a second-line brake pad might be physically identical with the OE version, the fit and function usually isn’t. The second-line pad might, for example, be too slightly thick to fit over a brand-new brake rotor. In too many cases, the function of the second-line pad may deviate from OE simply because it creates too much brake dust or too much noise. On the down side of function, the second-line pad may wear the rotors prematurely or may require more frequent replacement than the OE-spec pad.
Although many application-specific parts are made in the United States, the only way for any manufacturer to cut manufacturing costs is to take some engineering, design and production shortcuts. Shortcuts in manufacture mean taking the long way around on installation and customer satisfaction. Enough said about form, fit and function.
