Lookin at an 01 crewcab, leather,4x4,no rust. Truck has 250k on it, new water pump, batteries, injectors, all stock. Says it runs perfect and shifts great, what other things are known problems for the 6.6? This would be my first diesel so just making sure I ask the right questions. And what's the best mods for better mpg's, the guy said it gets about 20mpg now. Thanks guys

 

Injectors are the main bitch with the LB7 & early LLY Duramaxs. If they've already been replaced thats great, but how long ago, who replaced them and do they have any sort of warranty on the new injectors or the labor would be the best thing to find out. Other than that the CP3 (injection pump) can get weak as well as the FPRV (fuel pressure regulator valve) can wear out and you can start having low fuel pressure issues. The FPRV is an easy fix, but the CP3 on the other hand is a hell of a task to replace and they are expensive. As far as mods go, a good turbo back exhaust and a custom EFI Live tune will go a long way on a duramax.

 

Love mine main thing you already know is the injectors and as long as the trans was taken care of (new filters regularly) because the allison has a spin on external and an internal inside the pan but those dont usually give much trouble, the trans should be good to roll. The cp3 is 2500 to 3000 to replace if you install a lift pump that will help your pump and injectors out because the lift pump pushes fuel instead of your cp3 pulling it doing all the work. Have any more questions just p.m me and ill hook you up with mods and tuning