Overheating.
read the posts. That was one of the first things done

I just re-read everything you posted. Was the hydrocarbon test performed after the truck had been driven for longer than 30-minutes? Also, was it tested after the system was flushed? There's either a clog in the block, the intake, or the radiator -- OR -- it's a head gasket. The telltale sign is when the engine is under a load in 4x4 mode.
Last edited by Gary-L; May 8, 2012 at 01:03 PM.
Get a "no touch" thermometer, and check various points on the radiator.... if you have spots that are significantly cooler than the rest of the radiator, it's prolly getting clogged up.... Draining the block and seeing what comes out may not be a bad idea either.
Here is some more information I just remembered. When I first bought the truck it had worn 37" tires on it. I didnt think much of this, because I swapped a couple things at the same time, but these may be related.
When i put the new tires [true 37's, so they went from about 34" to 36.8" adding almost 50lbs a tire] I also swapped my thermostat for a 180 and replaced the coolant temp sensor and sender next to it. Before I swapped the sensors and stat, My gauge never rose above 1/4 of the gauge, after it rides right below half way. My gas mileage also went from about 13-14mgp to 10-12mpg. I assumed the gauge difference [which was huge] was just the new stat and the mileage change was the extra added weight of the tires and the 180 stat. Could I have damaged the sensor replacing it causing it to not go into a closed loop when it should? that would effect the cooling for sure and possibly the mileage. What would cause such a huge change in the gauge and could this all be related?
When i put the new tires [true 37's, so they went from about 34" to 36.8" adding almost 50lbs a tire] I also swapped my thermostat for a 180 and replaced the coolant temp sensor and sender next to it. Before I swapped the sensors and stat, My gauge never rose above 1/4 of the gauge, after it rides right below half way. My gas mileage also went from about 13-14mgp to 10-12mpg. I assumed the gauge difference [which was huge] was just the new stat and the mileage change was the extra added weight of the tires and the 180 stat. Could I have damaged the sensor replacing it causing it to not go into a closed loop when it should? that would effect the cooling for sure and possibly the mileage. What would cause such a huge change in the gauge and could this all be related?
Last edited by etdavenport; May 9, 2012 at 12:43 PM.
Your truck has two sensors. The one wire sensor is for the gauge. PCM couldn't care less about that one, it pays attention to the two wire sensor on the other side of the thermostat housing.
What does your gauge indicate when just normally driving?
What does your gauge indicate when just normally driving?
I just put the 195 stat back in and replaced the temp sensor. [one on right with 2 wires] now my gauge reads just over half way when driving [210]. it runs consistent but its running hot. And sure enough, 20 minutes on the hill was all it took to get really hot. I am looking for the OEM fan clutch and blade now [dealer wants almost $300] at a parts yard. I do not think even that is going to do it though. I checked the radiator hoses a while back and the inlet was about 17 degrees hotter than the outlet,











