PULLEY-ALTERNATOR 1W4846 - Caterpillar

have been some problems on a few of the earlier infrared thermometers. It has been reported that the barrel can become loose on some infrared thermometers. To tighten the barrel, first remove the decal on the lower side of the barrel, just in front of the trigger. Loosen the screw that is under this decal and move the barrel back into position. Tighten the screw and put the decal back in position on the barrel.
There have also been reports that some tests have not been accurate because of infrared energy reflected from other objects. This reflected infrared energy, which can be reflected in the same way that light is, can cause a temperature indication that is too high on the object being tested. These reflections can come from or be the result of a shiny surface, electric lights, the sun or a heat source too close to the object to be tested. Other objects that can give a wrong indication are polished (smooth) painted surfaces or shiney metal surfaces such as hydraulic cylinder rods or stainless steel exhaust stacks.
For example, on some marine engines the aftercooler water line can be near the exhaust manifold. If the water line is tested, the infrared energy from the exhaust manifold will increase the temperature indication of the water line.
Several methods can be used to limit this reflected infrared energy. One way is to put masking tape on the area of the object to be tested. Make sure that the masking tape does not have a shiny surface. Also, mailing labels or colored round labels can be used. These labels will also make identification of the test area easier if it is necessary to do the test again.
Another way to limit the amount of reflected infrared energy is to hold a piece of paper or cardboard between the source of infrared energy and the reflective surface of the object to be tested. Leave this paper or cardboard in position for approximately 30-60 seconds before the object is tested.
The best method to prevent reflected infrared energy is to take a temperature measurement on the opposite side of the object, if possible. This is the side that is away from other sources of infrared energy.
Special Instruction, Form SEHS8149 has complete instructions for use of the 6V6125 Infrared Thermometer (part of the 6V5000 Infrared Thermometer Group).