04 C70 Shredded serpentine belt, crankshaft spins freely

[dosbricks]

Strange... if you turn the crank, do the cams move? I don't really understand what you are saying is going on.

If the timing belt is still on and fine, is the harmonic balancer damaged?

+1 rspi. The OP's post needs clarifying.

[Ozark Lee]

Moderators?

'04 C70 would be a different forum. Wish I could help.

Actually the C70s are all P80 cars and this is the proper forum. The engines follow the P2 cars after 2000 but we do our best. They fall into the weird duck category - kind of like the '93 850s.

...Lee

[cuhfs]

1.) Sorry if I posted in the wrong forum ... Pretty sure the problem would apply across the board for the earlier models too. I will post this to the 2004 area too.
2.) for those not understanding whats going on. Serp belt split a few ribs, shredded, and got caught up behind the crankshaft pulley. The timing belt did not break. Timing marks appear ok possibly/maybe 1 tooth off. When I put a socket wrench on the crankshaft it spins with no resistance at all. Car does not start.
My plan is as follows based on the replies so far:
a.) Compression test.
If compression is bad... - plan for new head or new engine.
b.) If compression is good, pull crankshaft pulley as it may have a keyway tab and slot that was damaged.
c.) I have done about 10 timing belt and serp belt changes as a shade tree mechanic and would not have done anything different. Not sure why this happened.

Will keep you all posted in a few days. Any other thoughts are welcome.

[cuhfs]

Per Lee's post I guess this is the right place to post for this engine. Thanks

[cuhfs]

Removed the timing belt cover. Pulled out the shredded belt material.In a no start situation. Will follow steps noted above.

[cn90]

My theory is perhaps the serp belt was put on with one rib off. Just a theory.
Or the serp belt tensioner going bad, causing mis-alignment.

This is why I always use Conti OEM belt (timing belt and serp belt) and at 140K+, I always replace the idler/tensioner pulley on both the TB and the serp belt system.

This happens all the time: the serp belt goes bad (either from belt breakage or pulley(s) going bad ---> belt ended inside the TB compartment ---> ruined engine). Not specific to Volvo but any vehicle with TB system.

[mecheng]

I remember I had a gator back belt for another car I had, and it didn't have a continuous rubber line, it was sort of ribbed. That could cause a tracking issue

[precopster]

Crank abruptly stops while the momentum of the cams continue to drive forward. My 960 had a serp belt wrap around the crank pulley that killed 24 valves 5 years ago.

Hope yours survived. I'm concerned that your car doesn't start.

[E Showell]

I helped the owner with a compression test this morning (he didn't have a gauge and I do). We didn't bother testing more than two cylinders. Cylinder 1 didn't even move the needle of the tester from the resting, i.e., zero position. Same result on cylinder two. Didn't seem to be much point in testing the remaining cylinders. I'm pretty sure the compression tester is functioning as it should. He's weighing his options. Other than the obvious, the car is in great shape.

[Ben850]

Moderators?

'04 C70 would be a different forum. Wish I could help.

Actually the C70s are all P80 cars and this is the proper forum. The engines follow the P2 cars after 2000 but we do our best. They fall into the weird duck category - kind of like the '93 850s.

...Lee

I feel badly for jumping to that conclusion.

After seeing issues with C70s over the past few years, I realize they fall into the same group as a 1993 850 GLT. Somewhat mutant.
Apologies.
Sorry to hear of the actual damage.