Hi all, long time reader and first time poster.

I was driving my 2003 Volvo S40 when the engine shut off. I pull over and the car won't start either. When I pop the hood I see that the serpentine (accessories) belt is shredded. I got it towed to a mechanic and they called me back today and said:

1. a bad belt tensioner caused the serpentine belt to fail
2. that in turn damaged the alternator
3. it also damaged the timing belt, causing an engine misfire
4. which damaged the engine valves

I'm a bit skeptical since the timing belt has a cover so I find it hard to believe that the serpentine belt could have caused all of this. I was also driving at low speeds when it happened, the car wasn't going at 5000 rpm or anything. The mechanic quoted me $5000 for a new engine, but wouldn't a valve job be a lot less? Should I get it towed to another mechanic for a second opinion? I'm about to head over there to check out the car and have them walk me through it in person. Any advice would be appreciated, thanks!

 

That could happen. Those belts are incredibly strong, and when one breaks, it'll go somewhere. If you're lucky nothing else gets damaged. Repair of the engine is cheaper than $5000, but it takes longer and you invite some risks when you do that. The shop steered you toward a new engine because they would prefer to do that. If they repair it, and something goes wrong, then it's back on them. But with a reman engine you would have a guarantee from the rebuilder.

If you look at it, I would expect the timing belt cover to be broken. If it's not messed up, I don't see how you could jump time as a result of that event.

 

I've seen it plenty of times.

 

The mech might well be right. There's nothing about JUST a broken serpentine belt that will kill your engine immediately - sure, it'll eventually die when your battery goes dead from lack of an alternator, but if your car died immediately when the serpentine belt cut loose, something "mechanical" happened under the hood. I can think of other possibilities - like the belt snagged a cable or hose. But if I were a betting man, I'd bet your mechanic is right. If your engine was cranking and sounded "different" while doing so (like it's turning over a little faster than normal), then it's a near-certainty he's correct.

The one thing I'm struggling with is how the broken belt damaged the alternator, but I suppose it flailing around might have ripped a cable / connector off.

 

Yes, the car did have a fast crank when I tried to start it after it stalled. I inspected it in person and did see debris under the timing cover. Not sure about the alternator but that's in the same area so I figure they're probably right.

Here's the mechanic's written assessment for posterity:

So now I'm working on finding somewhere to sell the car to for parts or salvage. Thanks for the advice everyone.