I bought the truck when it had 95k on it. Bought a warranty. Had it about a month and the heater core went. Took it to the dealer for the repair. Just so happens,that dealer sold and maintained it for the original owner. Service manager told me that the truck had never had the coolant changed. I asked about the 5 year-150k mile claim....he told me that the 5 year is fine but to not let it go more than 50k on the coolant. He said, if I remember right, that the Dexcool turns acidic as it ages, which is why the core sprung a leak. He asked if I added any conventional coolant as my cooling system was smudged up. The truck was serviced by the car lot I got it from so who knows. Service rep told me that they replaced the radiator, it looked like it was starting to form numerous pin holes.
Was thinking about dumping the Dexcool in favor of a "diesel specific" coolant my buddy at NAPA sells. Have heard horror stories of folks not getting all the Dexcool out and a mud forming in the cooling system so I decided against it. My lower hose, all $70 of it, has had a drip on one of the 2 "T" connections on it for 5 years or so. Have been seeing puddles, at random, under the truck since returning home in Febuary. Digital temperature gauge has been floating quite a bit. Normally, when the truck is empty it will warm up and sit at 185-187*, unless it is cold. It has been running at 194*. When I was hauling the small excavator home to fix our pump house it hit 215*. It has never been that high. Even towing 12k pounds, in 115*, at 95 mph climbing one of the inclines on 93 in AZ the hottest it has ever gotten was 203*.
Hoping that the culprit was the lower hose. Leak was very sporadic. Put the pressure tester on it, pumped it up to 15 psi...week later was still at 15 psi. Next time I stated it within 30 seconds there was a drip. Shut it off, put the pressure tester back on it...nada. Next 4 times I drove it not one drop.
