Timing belt slipped off

[chapeau1]

I know I?m reaching here but my 2005 xc70 timing belt slipped off while driving. Upon inspection of the timing belt, it looks like some of the teeth are missing, maybe that was the cause of the belt slipping off? I understand that the valves are probably bent, but I think I have to try and start it. Wondering is there a way to get the timing straightened out before putting the belt back on? The water pump was started leaking a few weeks ago, so I was actually in the process of replacing the timing belt and water pump. I was a week too late...

Any help is appreciated!!

[Astro14]

I have never heard of a timing belt slipping off. This is a first for me

I agree that your engine is probably toasted. Even just one revolution with a stuck camshaft and you?ll have pistons hit some of the valves.

I take it that your intent is to verify that damage.

The old timing belt won?t work, not with missing teeth. So, if you insist on trying to start the engine, at the very least you need a new belt. The most likely cause of the belt coming off is actually a failed tensioner.

Resetting the timing is straightforward. You use the exact same timing marks on the crankshaft pulley, and the two camshaft pulleys, that you would use to install the belt.

[chapeau1]

I actually thought the belt broke, but upon inspection it was intact. I also assume the tensioner failed, not sure what else would cause the belt to slip off?

Would me just turning the crankshaft manually determine if the valves are bent?

[Astro14]

Turning the crank manually, how? With the timing belt in place and the engine back in correct time? No, it would not show if the valves were damaged.

The only way to know is to re-install the belt, time the engine, and do a compression check.

But, if the engine was running when the belt slipped off, I promise they're damaged.

The timing belt, tensioner, and idler, should all be done at the same time, specifically to preclude this kind of failure.

The directions in the "how to" section of this forum are excellent for doing the timing belt, they're from VIDA.

But in all honesty, you're looking at a new/used head to get this car right. That's a lot of precision work for a DIY and a big bill for a good* shop.

When you add everything up - it is likely more than this car is worth. I am sorry to say that, but it is likely true.

*Not all shops are good. You need to ensure that the block is still perfectly flat. The new head has to be perfectly flat.

[AKAMick]

The engine is a interference engine, valves will contact the pistons if the belt fails, but all is not lost if it happens as the valves are easily bent due the stems are relatively skinny and the damage to the pistons some times is just knicks, Removing the head to determine the extent of the damage is a good idea before condemning the entire engine, The valves can bend and the head remain undamaged, guides can be perfectly fine, Replacing the damaged valves and lapping them in to the head will save the head component, all this depends on the skill and experience of the "mechanic", might be beyond the capability of a "novice", as it is a labour intensive repair, Repaired a couple of Volvo timing belt failures that went on to lead useful lives,