Will the spread between eot and ect temperature be greater when towing a heavy load than running 65 empty Thanks for your reply

 

My temps go up when pulling. Especially the mountains. But my spreads still stay with in 7 to 9. They Usually run in the upper 190s when pulling flat. My normal spread with out pulling is only 1 or 2 difference

 

Once you're fully warmed up, EOT will be slower chasing ECT down, especially if you start coasting down a hill. I wouldn't worry about "spot checking" your split, look at where it averages when you're not climbing hills and coasting down them. It's not a pass/fail critical fault type deal where the engine blows up if you hit 15*, it's an aggregate failure that builds up over time, and you're looking for variances from your normal to indicate the cooler is clogging.

 

yes, there can be as much as a 20 degree difference in a health engine. Very dependant on the load, the speed and the terrain. As noted it's common to have a big difference when you crest a hill and coast down the other side. Coolant drops very quickly with the fan on and no load, and oil follows about 3 - 5 minutes later.

Brian