Professional diagnositic tools hold your hand to both the lower and upper radiator hoses

How you can Diagnose a Car or truck That's Running Hot 1Check the antifreeze/coolant level in your radiator. Wait until the car or truck has cooled down and the engine is cold, and then remove the radiator cap. If the fluid level is sufficient, you should be able to visually see the liquid inside. If it is low, add more according to your car's specifications.

If you have to add more than a pint of fluid Professional diagnositic tools, it is possible that you have a leak.2Check your oil level. Remove the dipstick from under your hood and wipe it clean with a rag. Reinsert the stick, pull it out and then read the level based on the markings on the stick. Oil serves as a lubricant and if there is not an adequate amount, then your automobile will be working harder to perform and this can cause overheating.3Investigate the thermostat. This should be done with the automobile powered off car diagnostic software, and while the engine is slightly warm. This problem is one that will most often need to handled by a mechanic.

For a do-it-yourself check, however, hold your hand to both the lower and upper radiator hoses; both should feel warm to the touch. If you have just one that is warm while the other is cold, the thermostat could be the culprit causing the overheating.4Visit your mechanic. Unless you are trained to handle these problems, it is best to leave them to a professional. A mechanic can hook your automobile up to a diagnostic computer that will give a reading and a specific report on the problem(s) with your vehicle.