The engine is equipped with a charge air cooler. The insert type charge air cooler is mounted in a welded casing (air trunk) . The trunk is bolted to the engine block. Standard is a two-stage cooler mounted. The first stage, through which the charge air flows, is cooled with water from the HT cooling system and cools the charge air till approx. 90-100°C. The second stage is supplied with water coming from the LT water system and cools the charge air further till the required temperature of approx.. 50°C. By controlling the water flow through the LT cooler the charge air temperature can be kept constant at the required temperature. The circulating coolant water should always be under positive pressure and should be as clean as possible. The operating air temperature should be maintained by controlling the coolant inlet temperature. Whilst the engine is running the air and coolant temperatures and pressures at inlet and outlet should be checked and logged periodically. Variations from normal indicate faults developing such as fouling of the film plates or obstruction of the water tubes. Check daily, during operation of the engine, the working of the telltale hole at the free end of the charge air receiver. The function of this hole is to inform the operator the presence of water in the charge air receiver. Under normal condition only compressed air should escape from this hole.