G3612 & G3616 TWO STAGE AFTERCOOLOER Caterpillar


Operation And Maintenance

Usage:

The two stage aftercooler should be inspected, cleaned or replaced at the following service intervals and engine maintenance operations:

10,000 hours ... Clean

Top end overhaul ... Inspect/Replace

Major overhaul ... Inspect/Replace

Cleaning

NOTE: Cleaning should be done after every 10,000 hours of operation.

The two stage aftercooler can be cleaned without removal from the engine if fouling or blockage of passages is light and has occurred over a short period of time (less than 10,000 hours). If heavy fouling and blockage of passages is suspected or evident the aftercooler should be removed from the engine before cleaning.

Cleaning While Installed On The Engine

When it is determined from the performance figures of the aftercooler in operation that an internal inspection is advisable the coolant should be drained.

Water Side

Remove the cooling system tubes and branch header to inspect the interior of the tubes. Use special brushes provided in 145-0316 Cleaning Kit where deposits are soft, which will occur in the majority of installations. Rotate the rod in a clockwise direction to avoid unscrewing of the brush head from the rod. The rod assembly may be attached to an electric hand drill.

Air Side

The fins can be examined by removal of the air inlet adapters since deposits will gather on the leading edges of the fins. With the air inlet adapters removed most of the deposits can be brushed away with stiff nylon brushes (not wire brushes). Use of a low pressure steam jet or compressed air blower will facilitate removal of heavier deposits.

Cleaning After Removal From The Engine

In particularly bad working conditions it may be impossible to clean the aftercooler thoroughly while it is installed on the engine. Remove the aftercooler and strip the unit down so that the tubestack and sideplate assembly can be immersed in a cleaning tank. When the top and bottom headers have been removed, the tubestack comprising of the sideplates, tubeplates and cooler sections can be immersed to clean the fins and descale the tube bores.

Air Side

To clean the fins, immerse the tubestack in a tank containing a solution made from degreasant powder and water. The powder should be non-toxic and free from fire risk. The solution should be agitated by either raising and lowering the tubestack into the tank or by the means of a jet of steam or air, this will accelerate the washing process.

Water Side

The coolant circuit should be effectively screened to reduce the partial or complete obstruction of the aftercooler tubes by debris or marine growth. Partial obstruction of the tubes causes excessive turbulence of the fluid within the tubes and rapid corrosive attack may occur. These obstructions are generally loose and can only be effectively removed by mechanical methods. The suction and delivery filters (when installed) should be inspected and cleaned at regular intervals since these can cause an apparent loss in performance of the aftercooler.

The various chemical descaling processes available will remove scales consisting mainly of calcium carbonate with ease. Scales consisting of calcium sulphate or silicates may not respond to chemical cleaning, in which case mechanical methods should be applied ensuring that there is no damage to the tubes.

The silicate scales seldom respond to any form of cleaning and when the scale thickness seriously effects the aftercooler performance, the only remedy is a replacement tubestack. Fortunately silicate scales are not as frequently encountered as the other types.

Leaking Tubes

When a coolant leak is suspected or established, initially identify which coolant stage is leaking by filling one stage of the aftercooler with coolant and observing for leakage. Then fill the other stage of the aftercooler and observe it for leakage.

After it is known which coolant stage leaks, pressurize each tube individually with compressed air and spray water on the tube or if possible immerse the core in water and observe if any air bubbles are originating from the pressurized tube. This will pin point the tubes that are leaking.

Leaking tubes may be sealed with turned hardwood plugs provided in 145-0316 Cleaning Kit. The maximum number of tubes that can be plugged without unduly impairing efficiency is 10 percent. When more than 10 percent of the tubes are found to be leaking the tubestack and sideplate assembly should be replaced.

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