Wayne D Posted January 7, 2016 Share Posted January 7, 2016 Hello, I have 2007 Mack with a 12L AC motor that has way too much valve lash. This occurred after an ether induced runaway start. I am not too familiar with this motor.Any ideas as to what may have happened? Thank you for your help.Wayne Quote Link to comment https://www.bigmacktrucks.com/topic/43417-excessive-valve-clearance-on-2007-12l/ Share on other sites More sharing options...
BGarofalo Posted January 8, 2016 Share Posted January 8, 2016 Start by checking for bent push rods. They are the weak link and typically bend first causing excess lash. If you had enough ether in that thing to cause it to runaway I wouldn't be surprised if you have other more serious issues. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/43417-excessive-valve-clearance-on-2007-12l/#findComment-319006 Share on other sites More sharing options...
Popular Post turckster Posted January 8, 2016 Popular Post Share Posted January 8, 2016 Broken rollers on the lifters. They are made of a ceramic material. Also would check the h-rings- they are the alignment rings for the roller lifters. There could be other damage as well in the valvetrain, I would inspect all components. 3 Quote Link to comment https://www.bigmacktrucks.com/topic/43417-excessive-valve-clearance-on-2007-12l/#findComment-319015 Share on other sites More sharing options...
Dieselwrenches Posted January 9, 2016 Share Posted January 9, 2016 I would start by draining oil. If you find ceramic pieces then drop oil pan and inspect cam. Quote Link to comment https://www.bigmacktrucks.com/topic/43417-excessive-valve-clearance-on-2007-12l/#findComment-319194 Share on other sites More sharing options...
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