2017 Chevrolet Malibu Intermittent No Start

You know it is a really interesting problem when Bernie says it is “cool” and starts nerding out as the ecm starts to roll the dice.

Great diagnosis Bernie. Looking at the picture you had of the camshafts, it appears that the trigger wheel on the old one is approx. 90 degrees out from the new one. Are these just pressed onto to the shaft and get loose and rotate? Or did something else happen that would cause this?

I think I saw the slot in the end of the cam had rotated as well. Is it one with the trigger wheel, and does the slot drive something that might have seized and caused the problem?

Bernie said the trigger wheels are pressed onto the camshaft. The camshaft drives the vacuum pump, the vacuum pump seizes; breaking the drive mechanism and the drive lugs break and fall down between the head and the trigger wheel, thus moving the trigger wheel on the camshaft.

Jeff, Thanks for clarifying how it failed. Excellent demonstration! Randy

Thanks Jeff, I figured something like that had happened.

Thanks Bernie, excellent presentation as usual.