I own two cars: a 2003 Acura TL and a 2005 Volvo S60.
I've been told that depending on what car you drive, a failed timing belt can result in immediate engine damage.
I would like to know (not just about my two cars, but in general) how I can know if a failed timing belt can result in immediate engine damage for a particular car.
Check with the manufacturer to see if it's an interference engine or not. Even so, that's not an absolute guarantee. Occasionally someone with an interference engine will get lucky and not have the valves and pistons attempt to occupy the same space at the same time. I've also heard anecdotal reports of non-interference engines suffering damage when losing timing belts at high RPM. Not sure what the mechanism of damage would be though. Could be inversion of cause and result... :-)
tl;dr: a broken timing belt always means some sort of damage.
Like Brian says, interference engines are obviously at risk of the most straightforward damage: pistons hitting valves with great energy, causing ma$$ive destruction.
Here is a cautionary video illustrating some of the parts that can be immediately broken, causing a appalling domino effect of damage.
Even if the pistons and valves can't technically occupy the same space, a broken timing belt is effectively a high energy whip slashing around in your engine bay. The easiest way to eyeball what could be damaged by a broken belt is to look at all the components that are dependent on, connected to or adjacent to the belt. Assume that they'll all be hurt and that, in their death throes, they will lash out at other blameless parts purely out of spite.
My belt just broke on my vw 1.8t and it bent valves, Most of the time your just going to need a valve job and timing belt, in other cases, the head can crack, valves blown through top of motor, pistons split or crack, etc. All depends, nothing always breaks the same, theirs always some difference in failure.
Short of tearing apart the engine, there's really no way to tell externally. The manufacturer knows, and sometimes it'll be listed in the owner's or service manual. Otherwise, using something like Gates lookup will usually get you the right answer.
FWIW, your Acura almost definitely has an interference design (I believe all or most Hondas do). Not sure about the Volvo.
