Hyundai Repair: Hyundai Terracan overheating, hyundai terracan, coolant temperature

Question
We have a Hyundai Terracan 2006 model.  Have been having problems since mid 2009 with the temperature gauge rising when pulling our caravan.  We are not exceeding the towing capacity of the car.  Other people we have spoken to pulling same size caravans with their Terracan have not experienced this problem.  Only started in 2009.  Previous trips with van - no problems experienced.  Temperature gauge rises but we have not actually boiled.  Not losing any water.  Have had investigations through two Hyundai dealers who have found no problems.  As I mentioned, it only happens when we are towing.

Answer
If your temperature gauge isn't actually going into the red zone, then it's not overheating and there may be no repairs necessary.

First, it's a good idea to check the accuracy of the gauge.  Do this by comparing the actual coolant temperature to the gauge reading.  Your coolant temperature sender or gauge could be defective.  While I don't have any specific knowledge of the Terracan, if the coolant gauge is set up like other Hyundai vehicles, it's possible that in incorrect gauge reading can be caused by poor engine ground.  In that case, you could need a battery cable or engine ground strap.

If the engine is actually overheating, the type of driving you're doing when the overheating occurs will assist you in locating the problem.  I'm going to assume that, as you say, you have no leaks and the coolant is full.

If the problem occurs while driving at significant speed (usually 55km/hr or more), you should suspect a radiator heat transfer issue.  In this case, your radiator may well be partially clogged or there may be an issue preventing air from crossing the radiator such as a blockage in the air intake, missing or damaged body components which are designed to direct air through the radiator, or damaged fins on the radiator.

If the problem occurs only when stopped or at slow speeds, you should investigate the possibility that the cooling fans are not coming on.

If you'd like, you can do a cooling system audit as follows:
1.  When cool, remove the radiator cap and check coolant level.
2.  If low, check for leaks.
3.  With the cap off, start the engine and observe the coolant.
4.  As the engine reaches operating temperature (usually around 82C), the coolant should flow.
5.  Since the vehicle is not moving, coolant temperature will eventually rise after flow begins.  As the temperature reaches a predetermined level, the radiator fans should turn on.  This should occur prior to boiling.

This won't tell you whether the radiator is clogged, but does check for leaks, test the thrermostat, and test the fans.