Broken inj. hold down screw

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Apr 22, 2013 | 10:13 PM

540milotalon

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Laughing Gas

Joined: Sep 2007

Posts: 869

Likes: 5

From: Near Shenandoah Valley

Broken inj. hold down screw

I finally found the miss in my work truck! After checking, rechecking wiring, A/E readings, swapping IDM's with conflicting readings it was one inj. backing out because of a broken bolt. Not sure why, and will try tomorrow to get the broken aprox. 1/4" of bolt out.

Any thoughts why it broke?

Apr 23, 2013 | 05:45 AM

427 fordman

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Joined: Feb 2009

Posts: 10,408

Likes: 75

From: Plankinton, SD

IIRC from the factory, the injectors were torqued at 100 inch lbs, not 120 like recommended now. That injector bolt probably came loose over time and lots of use, and you got what you have now.

Apr 23, 2013 | 08:41 AM

OldWoodsDiesel

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Joined: Oct 2011

Posts: 1,647

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From: Exton, PA

just curious - did you have any signs of combustion entering the valve cover cavity as a result of the loose injector?

I've got a similar half-miss on the right side of my engine I can't seem to diagnose. truck starts and runs fine and makes good power, but it has a 'blub blub blub' idle. my injector buzz test sounded and came back fine. I still need to do the contribution test and then go from there... i'm hoping its not bad compression (caused by bad rings) on a cylinder...

I ask about the appearance under the valve covers, though as I had mine off recently to do my glow plugs and everything looked normal to me on both sides, though I didn't specifically check for loose injectors or missing injector hold-down blot heads...