Helluva thread! I didn't read EVERY page (haha) but I spent an hour or two on the thread. I had a 07.5 2500HD gasser that I knew everything about. I sold that truck shortly after buying my dmax in late August '18. And now trying to educate myself on aspects of the diesel world I know little about.
I figured out early on aspects of regular maintenance on my LMM were ignored.. Silver lining is few items were ignored for too long, so I didn't have to invest much more beyond purchase price. However, about two months ago the truck started to develop a hiss only when turning left. I figured it the best time to get fluids changed..
About three weeks ago I did the brake fluid flush and refill. I didn't see much improvement on brakes, but I knew by the icky green-black color of the fluid that the system would like the new drink. Then just this past weekend, I did the power steering fluid flush per this process.
I have to say, it went very well for me. My system took 2.5 qts before the fluid ran clean. Only thing is, I was so focused on keeping my hand from getting bloodied by the bracket near the hydroboost system that I forgot to take the cap off the power steering fluid reservoir before pulling the hose... doh! Aside from that, holy smokes! The brake pedal position and overall break function was improved dramatically!! Steering indeed feels buttery.
On the not so good side, the hiss is still rather apparent (during left turn only), and turning left is still tougher as was before. There might've been a subtle improvement for the left turn, but it's quite possible a mind game is happening.. I hear the noise still, so the other related effects are just as bad..
Having read much into this thread and another one about troubleshooting steering issues on the LMM, I'm staring to think the steering gear is the next component to look at. Since I'm still learning here, anyone have some more insights on the topic?
2008 Silverado 2500HD CCSB LTZ Diesel
Edge CTSII Monitor, Cognito 7-9" lift running just over 7", 35x12.50 KO2's on 18 Fuel Kranks, Fox 2.0 mono tube shocks, Firestone Ride-Rite bags with 4" spacer
Axle wrap bars, Kennedy lift pump, air intake, DPF & EGR delete, tune