My volvo S40 has what’s called an intereference design engine, basicly what this means is that if the timing belt were to break the valve would stop moving and would hang in a position that would ‘interfere’ with the pistons path of travel. It wouldn’t really be an ‘oops pardon me while I squeeze by’ type of interference it would be possible broken piston heads and bent and broken valves.

Thus it’s recommend that the timing belt is replaced ever 100k miles, well right now I’m over 120k and I’m nervouse to say the least.

My dad was kind enough to help me out(did most of the work) and we got it done.