Freewheeling Engine

What does the term “freewheeling” mean? How does it differ from a “non-freewheeling” engine

I thing ‘freewheeling’ means an engine that, when you let off the gas, is not connected to the wheels. For example, if you are coasting down a hill, a freewheeling engine will not help slow the car.

Why do you ask?

Some of the regulars on this forum refer to a non-interference engine design as a “freewheeler”. This would mean that if the timing belt fails, valve damage is not likely to occur. An interference engine, or perhaps “non-freewheeler” is likely to have valve damage in the event of a timing belt failure.

Could you tell us where you heard this term and in what context it was used? Right now, we are guessing.

In your engine there is either a timing belt, a timing chain, or a timing gear set. Essentially, these keep the top half and the bottom half of the engine running in sync. If the belt/chain/gear breaks, the engine quits running. In a freewheeling engine, the top half and bottom half just spin and eventually stop. In a no-freewheeling, ot “interference” engine, the moving parts of the top and bottom (valves and pistons) can hit each other, resulting in major internal engine repair.

Yep, there are two very different meanings for the term. Here’s description related to disengaging the engine:

Hey Buck-My name is George and I’m the one who asked this question. I’m not a mechanic but I am studying for the ASE P2-Automobile Parts Specialist exam. I liked your answer to my question and I would like to know if you would be available to assist me by answering a few questions from time to time. If so, please email me directly @
Thanks for your help
Sacramento, Ca

If you happen to pass the test it probably would be best not to let anyone know about it. Some here equate passing a test with the inability to do real work, for the record I do not happen to feel this way about the ASE’s, good luck.