Hey all, owner of a '97 Coach Ed. LS400 here with 230k miles. Have had many problems with it, addressed in another thread and are not necessarily relevant to the problem at hand. Driving it about 2 months ago when it started making more noise than usual and vibrating noticeably at idle. Checked it to find that the accessory belt was making the noise; the harmonic balancer started to separate into the inside ring with keyway and rubber dampener and the outside ring with teeth to mount the belt (shown below). Tried to limp it home, then it just died on the highway so I pulled into a parking lot, the outside part of the harmonic balancer ate into my lower timing cover and sheared the crank sensor housing which I'm sure is what killed it. Thankfully didn't eat into my timing belt but I had to order a new balancer, timing cover, and crank sensor (the sensor is OEM). Replaced all three in a couple of hours, and the car would run intermittently but has great trouble starting, it'll turn over but takes many attempts to catch (like 10-15) and if it does it seems pretty violent. Pretty done with this car as of now, have been bumming rides from others to work and school and would rather have a functioning vehicle, if anybody knows of any input or fix to solve this no start that would be great, I doubt that I can sell it in this condition with as many issues as it already has. Thanks everyone
Old vs. new crank pulley

 

Was there any damage to the crank angle plate? I think some may call it a crank trigger.
The crank sensor is completely useless without this stamped steel part. They work interdependent of one another. The car will not start without it.

The sensor won't pick up an accurate, consistent signal if the teeth on the plate/sprocket are bent or sheared slightly.

 

I did not see any damage to it, I replaced it with the keyway but I could have put it on backwards. Also, if I get the car started, it stays running and doesn't cut out, just no start for a while. Could this be an ECU issue?

 

I'm unsure if installing it backwards would affect the signal, but the teeth would likely destroy your timing belt in a hurry as they would be angled inward.
It's tough to rule out a potential ECU issue completely, but the odds of one conveniently showing up when the harmonic balancer disintegrated is very low.

Edit- I keep calling them teeth, which may not be the best term. They do not drive or pull anything like the teeth of a sprocket.
The "splines" create a signal which the crank position sensor sends to the ECU. But if installed backwards would act like teeth and chew up the TB.

 

I doubt I installed it backwards then, since the replacement I drove the car about 3 times but stopped due to the difficulty starting. The timing belt should be intact. Is it possibly an issue related to the crank sensor housing being sheared into by the balancer failure? The sensor fit in no problem but the outside metal is visibly damaged.

 

It didn't click with me until today, as you've called it the crank sensor housing.
This is the front of your oil pump and the crank sensor mounts inside the short cylinder.
How badly was it damaged? I'm guessing you can't take a pic if the timing cover is in place...

 

It was sheared into pretty good. I'm not sure if this will affect function but the sensor seemed to go in without an issue so I think it was just outside damage. Is this another part that I will have to replace? Thanks