Had my truck in the shop for a new oil cooler and EGR delete this past week. In preparation, I flushed the cooling system using what seems to be the most prescribed method.... drain system (remove lower rad hose and driver side block plug), remove t-stat, tap water rinse x 3 or 4, Restore, drain, tap water rinse x 3 or 4, Restore +, tap water rinse x 3 or 4, distilled water rinse x 3 or 4. I didn't go as far as replacing with ELC since I knew they'd have to drain at least some of the system to do the oil cooler swap and EGR delete. No big deal, I told the tech what I had done and asked them to top off with distilled water I left in the truck after they had it all put back together. System was VERY clean when I dropped off the truck. When I checked in on it on Friday, they had it back together, but it had a huge turbo air leak due to not getting it lined up correctly on reassembly. I pointed them to a thread here on the .org that gave them some hints on how to get it back together properly. Anyway, when I was there on Friday, I glanced at the degas bottle and sure enough, it was still crystal clear. They had topped it off using 2 gallons of the distilled water I had left.
Fast forward to today. Turbo is back on, but on test drive tech noticed some hesitation. Did some digging and found that MAP sensor was way plugged with carbon and junk. Cleaned that out and test drove it again and it seemed great. I picked it up, it ran better than it has since I owned it, so I drove it home and parked it so it could cool down and I could drain it one last time before adding the ELC and topping it off with distilled water. Well, when I took off the degas cap, the fluid in the bottle was NASTY! Looked like there was sediment and who knows what in there. I drained it and filled with distilled again to flush. Now of course I have to get it up to 190* so the t-stat will open and then drive it for several minutes with the heater on full blast. I've done that once now and it's dark, but flashlight on degas shows some nasty stuff in there still. I bought more distilled water so I can do another 3 or 4 flushes, which is the plan, but...
what the heck happened to my crystal clear clean cooling system?