Startup Fail

Discussion in '2005+ Mustang GT 4.6L Tech' started by rschmid123, Jul 24, 2021.

  1. rschmid123

    rschmid123 Junior Member

    Finished rebuilding my 3v engine. When I went to start it, it cranked fine but struggled to start. When it did start there was some serious clanging from the engine, as though something were loose. My first guess was the timing/valve train. When I pulled the valve covers, I found three roller followers cracked in half. When I pulled the timing cover, everything looks as it should, however I have not yet verified the timing marks are still (or were) correct.

    My question is, what could cause the rollers to crack? Is this an indication the piston came up while the valve was open and slammed the valve up into the follower? I'm really hoping there could be another cause, otherwise those three valves are probably damaged. The crack is complete (two pieces) and side to side on one side of the roller (roller was intact)

    Appreciate any feedback on this.....
  2. Midlife Crises

    Midlife Crises Senior Member

    That’s a pretty good indication the cam or cams are out of time. Valves, guides, followers, lash adjusters and pistons can all be damaged easily when valve to piston clash occurs.
    crjackson2134 likes this.
  3. Dino Dino Bambino

    Dino Dino Bambino I have a red car

    I hate to be the bearer of bad news but that sounds exactly like what happened. A look inside the relevant cylinders with a bore scope would probably confirm that. Prepare yourself for pulling the heads as the next step.
    Can you post some photos or a video of the crank and cam timing marks so we can see them?
  4. rschmid123

    rschmid123 Junior Member

    Thanks, I'll try a scope to see if anything is visible, but I think I will pull the heads. In pretty deep already and that's the way to be sure. If I don't and there's a bad seat or bent valve stems I'll be putting my head in the oven......:angry1:
  5. BAD3VLV

    BAD3VLV Junior Member

    The motor is out of time and there was most definitely piston to valve contact.
  6. 86GT351

    86GT351 forum member

    I would scope first. Don't go through the extra labor if you don't have to. Prepare for the worst and hope for the best.
  7. eighty6gt

    eighty6gt forum member

    Looks like truck 5.0's 2011/12 are about $3,000 these days for something with just over 100k miles.
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