03 6.0 broken flywheel question

batmantech · January 10, 2014

03 f-350 146,000 miles get towed in with cranks normal wont start. Driver stated sounded like muffler fell off drove few miles and shut off.

Realtive comp. even. ICP low 70 psi replaced IPR started right up ran ok old vale had small pieces on the screen and screen was ok. Power balance even but sounded quieter than normal. Started a few times then starter just spun. Found flywheel broken can see in through trans hole. Has a new oil leak at the front seal.

Going to check crankshaft endplay.. Question now is if endplay is a lot has anyone just replaced bearings? If only that thrust washer is worn. The thing ran ok and the relative comp was ok.

lmorris · January 10, 2014

If all else checks out, no reason why you can't. You have to buy a full set of bearings to get the thrust bearing anyways, so might as well do all of them while you are in there. I have changed crank bearings when I don't like what they look like when doing bed plate seals, but never for end play concerns.

batmantech · January 10, 2014

perfect circle

Crankshaft end play .009 spec is .020

mchan68 · January 11, 2014

perfect circle

Crankshaft end play .009 spec is .020

That looks exactly like one I had years and years ago. It came towed in diagnosed as a bad starter by another shop. Sure enough, after an unsuccessful repair, upon replacing the starter what you posted above was exactly what I had. Upon replacing the flexplate, was when the post-repair road test revealed an extremely harsh shifting transmission which was I surmised had caused the failure in the first place.

Keith Browning · January 11, 2014

The two main causes for cracked and broken flex plates are excessive crankshaft end play and missing engine to transmission alignment dowels.

Alex Bruene · January 13, 2014

I've seen quite a few broken 6.0 and 6.4 flexplates. Most have been under warranty. I've never done anything more than replace the flexplate, and never had one break again (to my knowledge), but most of these things come to us regularly still.

batmantech · January 13, 2014

This is a local company. We do all repairs on it. The dowels pins are fine, trans has never been out before. (I have done a 6.4 flexplate only a few years back and I see that truck on the road often)

After I installed the new flywheel I ran it without the trans in(reading in another post that it could be done.thanks to you guys and this site for that one) It now has a mean low end knock and a dead hole.

Worst part is this owner is a Chevy loving company with only a few Fords. Of course this is a plow, sand spreader and back up trailer puller too.

And so the story continues....