Intake valve lash
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5th Gear
Joined: Nov 2024
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Intake valve lash
Replaced lash adjuster and now the intake valve won’t close. Does the new lash adjuster need to be ran/oiled before it seats? Is there something I’m missing? Background below…
Picked up my second 2005 6.8 limited about a month ago and it had a misfire. After the usual plugs/coils, misfire remained, so I ran a compression test and found low compression on cyl 4. Ran a few more tests and confirmed the intake valve was not closing. Intake manifold and valve cover removed, removed the rocker and lash adjuster on cyl 4 and went to work cleaning the valve through the intake port. (It was caked with oil and carbon deposits, but I scoped the intake and cyl and see no evidence of damage or cracks) Managed to get it cleaned up and it was closing properly. Figured I’m already in this deep, might as well replace the lash adjusters, so the new one went in and I reinstalled the rocker. Intake valve is back to not closing with rocker and new lash adjuster installed. I remove the rocker and the valve closes all the way again. CAM is positioned so the valve should be closed. What am I missing?
Picked up my second 2005 6.8 limited about a month ago and it had a misfire. After the usual plugs/coils, misfire remained, so I ran a compression test and found low compression on cyl 4. Ran a few more tests and confirmed the intake valve was not closing. Intake manifold and valve cover removed, removed the rocker and lash adjuster on cyl 4 and went to work cleaning the valve through the intake port. (It was caked with oil and carbon deposits, but I scoped the intake and cyl and see no evidence of damage or cracks) Managed to get it cleaned up and it was closing properly. Figured I’m already in this deep, might as well replace the lash adjusters, so the new one went in and I reinstalled the rocker. Intake valve is back to not closing with rocker and new lash adjuster installed. I remove the rocker and the valve closes all the way again. CAM is positioned so the valve should be closed. What am I missing?
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