Lexus 2UR-FSE crankshaft failure, dealer blaming wear

[peace25]

I have a Lexus LS 600h (2UR-FSE engine). In July 2025 , a Lexus Main Dealer replaced the timing tensioners and inspected the chain (a major teardown). 10,000 miles later, the engine suffered a catastrophic timing jump, April 13 2026

The Current Situation:

The engine is now dismantled at the same dealership. They are claiming the cause is a "worn sprocket" (wear and tear) and are refusing liability.

The Evidence (See Photos/Video):

The crankshaft keyway is "walloped" and heavily deformed (oval-shaped).

There is significant fretting/galling on the nose of the crankshaft and the mating surfaces of the sprocket.

The sprocket teeth actually look relatively normal for the mileage; the "carnage" is at the center mounting point.

The Theory:

I suspect that during the July repair, the main crankshaft pulley bolt was either under-torqued or reused (if it's a stretch bolt), leading to a loss of clamping force. This allowed the assembly to vibrate/chatter under harmonic load, which eventually destroyed the keyway and caused the timing to jump.

My Questions for the Techs:

In your experience with the UR-series V8s, does a "worn sprocket" ever cause a steel keyway to shear like this?

Does this look like typical "wear and tear," or is this a classic case of a loose crank bolt/failed frictional joint?

Is that main crank bolt a "one-time use" stretch bolt on this engine?

I’m currently in a dispute involving the finance company and an independent inspector. I’d really appreciate any technical "ammunition" or sanity checks you can provide.


Anybody can tell me please how to upload images ? Thanks

[_Rodders_]

Good luck but I doubt you'll get anything out of them even though they probably did cause it.

[peace25]

_Rodders_ said:

Good luck but I doubt you'll get anything out of them even though they probably did cause it.

So far they are trying to blame the sprocket but after email lexus UK and asking them to have a look once again into all the components they sent me an email said it's possible that lexus branch have caused some damage in the previous work but they can't be certain ...

Now according to the email they sent they are saying the sprocket and crankshaft status are unknown at that time lol, when I checked my invoice , the mechanic notes states that he removed the old timing chain and measured it and refitted back , in this case the sprockets were exposed and while his in there of course he would have examined the crankshaft, the guides and everything else before reverse back everything in place isn't ?

Now Lexus UK is trying to say in another word that they are not responsible for what occur to my car and that I have to deal with Lexus branch directly, waiting this Monday to hear what they will say and if anything didn't move forward , I will get a mechanic inspector down here to give me a report and take it to the court and of course if it's on my favor .

It's bumper I can't upload pictures and video in here but I am.not sure if I have to contact the admins or what ?

Thanks