[Psyphertext]

My brain just pictured the torrid belt snap at-speed followed by the whip of it going anywhere while trying to follow a path with no belt tension. Yep, I have seen the episode of Mythbusters on retreads, makes me picture it under a hood.

[Red Lightning]

Originally Posted by Psyphertext

My brain just pictured the torrid belt snap at-speed followed by the whip of it going anywhere while trying to follow a path with no belt tension. Yep, I have seen the episode of Mythbusters on retreads, makes me picture it under a hood.

True story. Used to be it was V-drive belts that would snap and beat up stuff in the surrounding area. But serpentine belts, they’re tough. They can shred and still have a portion of them running through the pullies. This creates a kind of ‘wire wheel’ effect except with rubber. Serp belts can do much more damage, as we can see in this thread. A v-drive Belt would never do this.

To further my story, I swapped out the Vanos Solenoids with the other engine. Cleared codes, now she’s smooth as glass and mpg is increasing. The only code left now is for downstream O2 sensor heater on Bank two. I’m sure sensor replacement will be the fix.

[cwlo]

Thanks for the photo, and glad to hear you are back up and running.

[Efthreeoh]

Understood the car has a new engine. But no one mentioned this... You said you pulled the harmonic balancer. If you removed the balancer via the crankshaft bolt, then you blew the timing because the crank timing sprocket is not keyed to the crankshaft. You remove the balancer by the 6 bolts that attach it to the crank hub. If you have no compression then it could be the timing is so far off because the sprocket slipped out of time. Considering the amount of debris you found, it wouldn't be surprising.

Not sure why BMW decided not to key the sprocket...

[hassmaschine]

You don't need to remove the big center bolt to take off the damper. Just the smaller 6 bolts.

still, I think when I build my N52, I'm going to have that done. Stupid design. I've heard (and admittedly, it must be rare) that sometimes the bolt can come loose and the hub will slip.

[Red Lightning]

The engine swap went well. Replacement engine runs great. Due to cleaning and gasket replacement everywhere, she is clean and dry. No smoke either. Modern Imports in St Louis, Mo, a salvage yard, did right by us. It was also nice to see original gaskets, Mahle brand, were found available at Advance Auto parts. Total cost in parts was below $1,600.00. Not bad, In my opinion.

Thanks for the responses in this endevour.

Roll on!
Red.

[Red Lightning]

Originally Posted by Efthreeoh

Understood the car has a new engine. But no one mentioned this... You said you pulled the harmonic balancer. If you removed the balancer via the crankshaft bolt, then you blew the timing because the crank timing sprocket is not keyed to the crankshaft. You remove the balancer by the 6 bolts that attach it to the crank hub. If you have no compression then it could be the timing is so far off because the sprocket slipped out of time. Considering the amount of debris you found, it wouldn't be surprising.

Not sure why BMW decided not to key the sprocket...

Interesting, I only removed the six small bolts. What a rediculous design. Not keyed at all? That just seems foolish. Although I questioned design a few times on this job, I guess that's why engineers get paid what they do. There are times I've got to wonder though.

[hassmaschine]

somebody did an analysis that showed the crank bolt tension could safely keep the hub in place, and it would save $1 per crankshaft.

[Red Lightning]

Originally Posted by hassmaschine

it would save $1 per crankshaft.

I think you nailed it right there, because of the bean counters.

[Efthreeoh]

Originally Posted by hassmaschine

somebody did an analysis that showed the crank bolt tension could safely keep the hub in place, and it would save $1 per crankshaft.

Which is why, if you do not DIY (and use a BMW shop manual - or E90 Post ), take your car to a certified BMW tech.