The most common and most likely answer to this crossword clue is the 9 letter word RADIATORS
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Buddy explains!

The straight part
We know that "engine components" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case engine components = radiators.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RADIATORS mean?
RADIATORS noun- Anything which radiates or emits rays.
- A device that lowers engine coolant temperature by conducting heat to the air, through metal fins.
- (of buildings) A finned metal fixture that carries hot water or steam in order to heat a room.
- A type of antenna.