I have a decent understanding on motors but by no means am I an expert. I have a question that you guys can hopefully help clear up for me.

As stated in the title, my timing belt failed twice in 6 days. The first time it totally snapped while the car was running. The engine starting running extremely rough for about 5 seconds and then died. The serpentine belt also snapped. It bent every single valve in the engine and I ended up biting the bullet and getting a new (factory reconditioned) engine. The dealer said that it was just a freak thing and nothing I did and nothing else in the engine caused it. The car had 80k miles on it which seemed very low to totally snap a timing belt but this dealer had done an excellent job so far so the repair was done. After a week or so I get my car back, I drive it 6 days and it dies again, this time just turning off in the middle of driving. As soon as I popped the hood I see that the serpentine belt is frayed. Anyway, I get it towed back to them and they tell me that it has jumped time again, but at least the belt is still intact. Thank god the new engine came with a warranty because there was cylinder head damage.

Today they called me and told me that it was actually the alternator pulley that was bad and they missed it the first time. This bad pulley was causing the damage to the serpentine belt. According to the dealer "the first time, when the serpentine belt snapped, it was thrown into the timing belt causing it to also snap". They called me at work so I kind of just listened but wasn't thinking too hard about what they were saying. But upon hanging up I started thinking: Isn't the timing belt totally internal? And under a cover? How could a broken or frayed serpentine belt break a timing belt? It shouldn't be able to get anywhere near there.

Any help clarifying what's going on here? Thanks!

 

Yes it is, but several people in this forum have said that the serpentine belt broke and took out the timing belt. To do that, it would have to break the cover. If the cover breaks then of course very little else would need to happen to destroy the engine. Even a piece of the cover getting sucked into the timing belt would destroy everything.

I guess, and this is just a guess, that this happens when the serpentine belt wraps around the crank hub. There is a lot of force there. If it gets pulled behind the crank pulley it would break whatever it comes in contact with. I have not had this happen, so I never had to unwind it.

I am glad they figured it out.