I opened the hood before starting the truck today. The truck had not been started Monday through Friday, and was parked in the shop. Local temps have not been below 40 degrees at night.
The DMAX's upper radiator hose was significantly collapsed side to side. The coolant level in the overflow tank was showing a normal level. Squeezing the hose caused a slight clicking sound - probably the thermostat. I took the cap off the overflow tank - seemed like a slight vacuum, and the upper rad hose partially re-expanded, but not all the way. I did not have the digital camera at the time...
I've never added any coolant, and the oil level is normal. Fuel about 1/4 tank in the 56 gal Transfer Flow tank.
When I started the truck, it ran like crap - idle all over the place, and much louder - sounded like the pilot injection was off. The DMAX idle did not stabilize after about 30 - 45 seconds, so I shut it down and restarted - normal this time.
Last year I posted a similar occurrence with the upper hose collapsing (the truck ran normally). IIRC, it was about this time of the year with the weather getting colder. No real suggestions or similar events noted in the replies to that post. I tried a search but could not find that post.
This is only the second time that I have noticed this - but I normally don't open the hood before starting. I wanted to check the GREEN eyes on the batteries to see if there was any noticeable change with the StreamLight charger (trickle mode ~ 100ma) running for 5 days without a start -> both batteries had a large, bright GREEN eye.
Any ideas?