AOS Failure: what breaks first?

[911monty]

Based on some of the severe AOS failures i'd suggest removing the green plastic cam plugs and check for timing and rotation.

Apparently you want more. There are a several weak links in the cam drive system that can fail, but let's look at what happened to you. A previously healthy AOS fails after spin, not unlikely as oil accumulates in head from centrifugal force and overwhelms AOS, but this happens to a running engine. You say you restarted and a continuous smoke cloud ensues. How hard was the engine stop? A weak link in this scenario is the tang that drives the oil scavenge pump. If oil is not being pumped from the head the AOS also fails. Continuous smoke cloud. I'd certainly look here.

[maytag]

Originally Posted by 911monty

Based on some of the severe AOS failures i'd suggest removing the green plastic cam plugs and check for timing and rotation.

Apparently you want more. There are a several weak links in the cam drive system that can fail, but let's look at what happened to you. A previously healthy AOS fails after spin, not unlikely as oil accumulates in head from centrifugal force and overwhelms AOS, but this happens to a running engine. You say you restarted and a continuous smoke cloud ensues. How hard was the engine stop? A weak link in this scenario is the tang that drives the oil scavenge pump. If oil is not being pumped from the head the AOS also fails. Continuous smoke cloud. I'd certainly look here.

Thanks Monty; always helpful posts! I'll check the cams for sure.

See video, below. You'll see them come up on me as I recover from the spin. Then you'll see how the cloud goes. Does this look like I should consider the oil scavenge pump?
I shut the motor down after I pulled off track. Once back in the paddock (after a flatbed tow) I hit the starter; the motor turned about half revolution (-ish, haha) and then locked-up.

https://youtu.be/tCfB0xFVJhg

[911monty]

I guess I should have said pumps, there are two one on each head, but for the cost of 2 o-rings I'd absolutely remove and check. Just make sure to mark for proper orientation before removal, they will go on either side but oil passages won't be lined up.

[Gilles]

maytag, sorry about your engine!

Just a crazy suggestion.. this is what I would have done at my garage since it's basic and helps you with a starting point

After removing the plugs, try to rotate the crank (hopefully) for a couple of 360's. If it goes, then with a compression gage you can see if the cylinders are close to each other's and move on.

Good luck!