Broken Flywheel Bolts

[welshpug 1,657]

found the source of my lack of drive/engine troubles that occurred last week after shifting into too low a gear and slamming my poor engine into the limiter.

 

Sheared flywheel bolts and Dowel.

 

 

the flywheel was fitted about 18 months ago, re-using the original bolts torqued up to spec and threadlocked, no odd noises were head prior to the incident.

 

no damage seems to have been caused apart from very light marks on the end of the crank, the flywheel was still tight on the end of the crank, lucky the car runs with a TDC sensor and cut out as soon as the flywheel moved far enough for the timing to be incorrect, I think it it was still on a dizzy there would have been more damage as the engine would have continued to run.

 

am I going to be fine to fit 8 new bolts and a dowel? can't think of anything to check!

 

Though its not a failure I have experienced or heard of, I don't think its wise any more to skip past the sentence in the Haynes manual that recommends replacing a Tenner's worth of bolts!

Edited December 8, 2008 by welshpug

[dcc 855]

thats mighty impressive, would imagine the force required to sheer one bolt must be massive, let alone 8 bolts, and the dowel. im guessing the sudden impact would have been incredibly stressful on the engine. maybe its worth checking anything that might have got any of the shock from the impact?

[welshpug 1,657]

yes very, I was quite surprised myself, though what else to check short of stripping the motor and transmission down?

 

I don't know as yet whether the engine still runs, because it needs the flywheel's Timing teeth to do so, but it hasn't lost any oil, and the timing belt is still present, gearbox has no holes in it, though obviously until I get the engine back on I can't see if it still drives in all gears unless I strip it down.

[mr_exe 1]

I snapped a bolt on a tu lump because i'd not used the torque wrench and overtightened it, but thankfully the remainder of the bolt came straight out

[pip470 61]

That is amazing, really supprised that happened. Must of felt like you were going through the windscreen. although if it let go like that maybe it didn't? Can you confirm please welshpug.

[dcc 855]

Meir, check the big end bearings. the shock could have an effect upon their stability (unsure, but I'd think the shock would have gone through them for sure)

[welshpug 1,657]

nope, no going through windscreenage! clutch went straight back down as soon as the bang happened and I put it into 3rd.

 

big ends eh? good call, I'll drop the sump off and have a look.

Edited December 8, 2008 by welshpug

[chris1986 1]

i had a fiesta mk6 tdci do this once, turned out to be something internal in the engine that had broke

[large 33]

So thats why it wouold not start .

[dcc 855]

actually, if you tried to start it, would that not have caused damage inside the gearbox? forcing the flywheel arround and 'bouncing' it off the walls? or would the starter not have been in contact with the flywheel after the initial incident?

[large 33]

the starter had no contact to the flywheel, it was dark and we were not in a good part of Cardiff.

[welshpug 1,657]

the flywheel hadn't moved at all, starter was still engaging, but simply spinning the flywheel around on the end of the crank because the bolts weren't doing their job (clutch + release bearing stops the flywheel from coming away from the end of the crank)

 

no marks at all in the gearbox's bellhousing.

Edited December 8, 2008 by welshpug

[Toddy 7]

Can you turn the engine over by hand on the crank pulley?, or is the engine seized?

[welshpug 1,657]

that I haven't tried actually! I'll do it first thing tomorrow before I fit the new bolts.

[welshpug 1,657]

Turned the engine over by hand a full 2 revolutions, has good compression but no binding or odd noises, timing pins lined up perfectly.

 

Picked up the bolts earlier, they already have threadlock on them, just getting the old ones out by tapping them round with a punch till I can get some grips on them, dowel is going to be fun though, that's tight and flush

[Toddy 7]

Turned the engine over by hand a full 2 revolutions, has good compression but no binding or odd noises, timing pins lined up perfectly.

 

Picked up the bolts earlier, they already have threadlock on them, just getting the old ones out by tapping them round with a punch till I can get some grips on them, dowel is going to be fun though, that's tight and flush

 

Mig weld a nut onto it?

[welshpug 1,657]

good call, shall have to see if there's any gas left.

[Cameron 16]

Dayamn! That's pretty impressive. I expected carnage to have happened but I guess the input shaft will still hold it in place. Would be interesting to see a close-up of the ends of the bolts if you can get one, that way might be able to tell if they were sheared off or snapped by tension, or a bit of both.

 

Edit: Looking at those pics it looks like they have sheared so wouldn't have made much difference using new bolts. Although they are very blurry so I could be wrong.

Edited December 9, 2008 by Cameron

[DrSarty 90 1 Cars]

Edit: Looking at those pics it looks like they have sheared so wouldn't have made much difference using new bolts. Although they are very blurry so I could be wrong.

 

Well there you go; there was Mierion's mistake. Using blurry bolts!

 

What a div!

 

[Tom Fenton 1,541]

I'd also check it hasn't bent the g/box input shaft. It shouldn't have, but then again the flywheel shouldn't come off.....

[Cameron 16]

Yes, blurred bolts are bad, mkay? Ensure that you use ones with a macro function in future.

[welshpug 1,657]

think I need a new digi camera, couldn't get them much better than this

 

 

 

got the dowel out, bit of mig on the end of a bolt did the trick.

 

 

Edited December 9, 2008 by welshpug

[Mikey S 29 1 Cars]

it maybe just the flash of the camera, but are those bolts showing signs of fatigue? it certainly looks like it to me

[welshpug 1,657]

not sure, the breaks are clean, i.e there were no cracks previously (i've seen and experienced cracked components on bicycles)

[Mikey S 29 1 Cars]

not sure, the breaks are clean, i.e there were no cracks previously (i've seen and experienced cracked components on bicycles)

 

 

its more where the metal has turned white, furthest bolt on the left and the right appear to be the worst.

 

how over-revved was it?, as i over-reved my old 1.6 past 8k once and it was fine. is the crank pully running straight and true as the only real explanation could be excessive vibration.