Duramax Lifetime Supporter
Join Date: Aug 2012
Location: Carson City, NV Proud Participant, Federal Witness Protection Program
Regarding just the valve lash part of your question, I believe I have read here GMC did not specify a recheck period on valve adjustment (someone help me out here) but I can say when I did my injectors at around 155k last year all the valves were extremely loose. Don’t recall the spec I used for adjustment, but believe it was somewhat tighter than the factory number (10 thou?, help, again) and the engine ran much more quietly (as if putting LB7 and quiet in the same sentence makes sense).
Getting to the valve adjustments is a pia, and since many engines endure with noisy valves, I would be reluctant to go in just for that reason, since, well, keep reading.
While your numbers look excellent (notice my firm grasp of the obvious) casual observation of the experience of others here seems to point to around 75k being a nominal life expectancy for VCO injectors.
Cracked injector bodies are a failure mode from years ago and seldom experienced these days (fuel in oil) and the most common symptom of impending doom (as you are aware) is the dreaded “haze at idle”, as dripping fuel from fouled injector nozzles that don’t shut off properly begins to carbonize on the tip, disrupting the spray pattern and excess drops of unatomized diesel don’t combust and head out the exhaust.
Interestingly, other than a loss of mpg, LB7 Duramax with failing VCO’s run strong, until the owner becomes too embarrassed by the white clouds at stop signs to keep driving. And not to forget the possibility of a stuck open injector that will definitely ruin your day...
Looking down the road to the inevitable, folks are reporting good results with the improved design of SAC injectors, as used in all subsequent Duramax, and have sourced OEM fuel delivery models that won’t require special tuning (although to further complicate matters, some owners have installed somewhat oversized SAC’s w/o engine management mods and reported good results).
Depending upon your situation, this may be a good time to begin considering unloading the truck (I know, like most of us, you luv it!) or at least start a fund for injector replacement. DIY seems to run about $2500, with replacement by the Big Kids approaching $5,000.
Hate to be Catastrophizing, but thems pretty much the facts, as I see them.
Notice I have craftily avoided answering your original question, but maybe this bump will encourage others to weigh in.
2003 GMC Sierra 2500HD SLE ExtCab CA Emissions; 155k; Allison 1000 w/Transynd X2 Flush & Fill; 8' bed; AFE/CAI; MBRP 4" Exhaust; Side Tint, 33% VLT, rear, Limo; Smittybilt Stainless Side Nerf Bars; Sprayed-in Bed Liner; MadJack Fuel Filter Access Door; Regular Used Oil Analysis (latest available on request), Blackstone Labs; EGT/Boost Gauges; Dual Chrome Dipsticks, JC Whitney; Stainless Steel fuel filter head bleeder screw; New WP and Hydroboost; Billet Aluminum Fuel Filter Housing Spacer; Professionally repaired instrument cluster (new steppers and lamps); Does anybody ever read this s%#t?; Injectors under warranty @ 70k; 2nd set DIY @ 155k