Out of sight, out of mind, can refer to many things. As automotive technology "advances" or at least becomes more and more complicated, more and more things are out of sight and as a result, probably out of mind.
One recent radio commercial has the speaker talking about how he raised the hood on his car and discovered someone had replaced the engine with something out of a space ship.
While there really still is an engine in most cars and trucks, it may be hard to find many of the parts. Even 15 years ago, the engine compartment had changed enough that one mechanic said he hunted for 20 minutes before he found the power steering pump. He only found it by tracing the lines and said it was nearly inaccessible.
Some parts, such as a timing belt, were never that accessible in the first place and in the cars of today, they are completely out of sight. Therefore, for those car and truck owners who don't usually spend their spare time reading the owners manual for recommended maintenance schedules, it is a good thing if their mechanic is aware of something like a timing belt.
That is because the timing belt can break and, if it does break, it may cause a lot of engine damage.
The timing belt determines "cam timing," which determines when the valves open and close in regard to the position of the pistons in the engine. Proper "cam timing" in an engine is when the camshaft puts the valves in the correct position with the pistons, driven by the crankshaft.
According to Gene Leeper, Leeper Auto Service, the owners manual is valuable in that it will tell the owner and the mechanic if the engine in the car or truck has a timing belt. And if it does, the owners manual will also tell the owner if the engine an "interference engine" or a "non-interference engine." It will also provide maintenance intervals for the timing belt, which might be 60,000 miles, 90,000 miles or even 100,000 miles.
That bit of information is important.
If the timing belt breaks on a "non-interference engine," the engine stops and the vehicle probably must be towed. That is because there is enough clearance inside the engine so that the pistons and valves don't touch if the belt breaks or if something happens to put the engine 180 degrees out of time.
Put a new timing belt on a "non-interference engine," set the correct timing and drive the car away.
It is not so simple with an "interference engine." If the timing belt breaks, the valves may drop down and be hit by the pistons causing major and very costly damage. A tow and replacement of the timing belt is only a small part what is necessary for an "interference engine." It could easily require a major engine rebuild or even replacement.
Something may be out of sight, but if failure of a part which is out of sight could cause major engine damage, or at the very least, major inconvenience, it is best if is not out of mind.