Snapped crankshaft bolt

[Fraser Stephens]

My local garage was doing the timing chain and tensioners on my 2012 V8, and sheared the crank bolt trying to get it off. Goodness know what torque this took! The bolt head is interesting: the markings are not clear, so I (and they?) can’t know if it is a left or right threader... and the flats of the head indicate that they tried turning it both directions.

Where we go from here is uncertain, but my question to the group is has anyone heard of a crank bolt being so tight that it breaks when trying to remove it?

(And why did Ford change from one tread to another? Surely a strange bit of engineering!)

 

[greiswig]

Wow! No idea how beefy that bolt is. But the way I’ve always told what the thread direction is is using the actual engine rotation direction. IOW, think about that bolt head as having a lot of mass and inertia. You want it so that the engine rotation makes it tighten itself down against that inertia. So whichever thread pitch makes that happen with the stock engine rotation is likely it.

I am brand new to the LR4, so I can’t tell you which direction that would be.

 

[DaytonaRS7]

according to this video: lefty tighty, righty loosy

edit: see post in this thread
bolt head markings:
10.9 = remove counter clockwise
12.9 = remove clockwise

https://www.jaguarforums.com/forum/...olt-snapped-new-block-jaguar-xkr-5-0l-156933/

 

[ryanjl]

**** like this is why I'm fine taking my car into a mechanic for some jobs. If I did that in my own garage, my fitbit would burst into flames counting all the frantic pacing I'd do back and forth.

 

[Fraser Stephens]

An update for completeness: The garage managed to drill and (I assume) easyout the snapped bolt and the repair was completed. Various other parts were replaced (front timing plate?) and lots of labor charged, but as it was the dealer paying at least I didn't have to remortgage my house.

Timing chain rattle has gone, idle is smooth and 500 miles driven so assuming all ok. There is still a detectable engine vibration at around 3500rpm, but it is smooth below and above so I am ignoring that...

 

[Quijote]

What a story! Glad it was all sorted out in the end and that the car works well!

 

[gsxr]

Timing chain rattle has gone, idle is smooth and 500 miles driven so assuming all ok. There is still a detectable engine vibration at around 3500rpm, but it is smooth below and above so I am ignoring that...

Good to hear it's back in service. If the vibration is only around 3000rpm while accelerating, there is a TSB with a fix, adding a damper to the transfer case. If it's 3500rpm to redline, I'd wild guess engine mounts...?

 

[Fraser Stephens]

If the vibration is only around 3000rpm while accelerating, there is a TSB with a fix, adding a damper to the transfer case. If it's 3500rpm to redline, I'd wild guess engine mounts...?

Might be the former - do you know what the TSB number is?

F.

 

[gsxr]

Might be the former - do you know what the TSB number is?

F.

Sure, it is LTB00305NAS3. See attached PDF. My 2010 felt exactly as this describes, during medium to hard acceleration, between 2400-2800rpm. Installing the damper cured it 95%. Why JLR didn't have this installed as standard equipment, I don't understand...