(126) Cooling System Troubles.
Overheating caused by deposits of scale or lime in the jacket is one of the most common causes of an excessively hot cylinder. When hard water containing much lime is heated, the lime is deposited as a solid on the walls of the vessel forming a hard, dense, non-conducting sheet. When scale is deposited on the outside of the cylinder walls it prevents the transfer of the heat from the cylinder to the cooling water and consequently is the cause of the cylinder overheating. Besides acting as an insulator or heat, the deposit also causes trouble by obstructing the pipes and water passages, diminishing the water supply and aggravating the trouble.
Scale interferes with the action of the thermo syphon system more than with a pump, as the pressure tending to circulate the water is much lower. Whatever system is used, the scale should be removed as often as possible, the number of removals depending, of course, on the “hardness” of the water.
Large horizontal engines are usually provided with hand holes in the jacket, through which access may be had to the interior surfaces on which the scale collects. Under these conditions the scale may be removed by means of a hammer and chisel.
The scale may be softened by emptying half the water from the jacket and pouring in a quantity of kerosene oil, the inlet and outlet pipes being stopped to prevent the escape of the oil. The engine should now be started and run for a few minutes with the mixture of kerosene and water in the jacket; no fresh water being admitted during this time. After the mixture has become boiling hot, stop the engine and allow it to cool; it will be found that the scale has softened to the consistency of mud, and may easily be washed out of the jacket.
The work of removing the scale can be reduced to a minimum by filling the jacket with a solution of 1 part of Sulphuric Acid and 10 parts of water, allowing it to stand over night. The scale will be precipitated to the bottom of the jacket in the form of a fine powder and may be easily washed out in the morning.
If the jacket water is kept at a temperature above 185° F. the amount of scale deposited will be nearly doubled over that deposited at 160° F.
Wash out sand and dirt occasionally, a strainer located in the pump line will help to keep the jacket clear and free from foreign matter.
If a solution of carbonate of soda, or lye, and water are allowed to stand in the cylinder over night, the deposit will be softened and the work with the chisel will be made much easier.
If a radiator is used (automobile or aero engine) the deposit can be removed with soda, never use acid, lye, or kerosene in a radiator or with an engine with a sheet metal water jacket.
Obstructions in Water Pipes. Poor water circulation may be caused by sand, particles of scale, etc., clogging the water pipes, or by the deterioration of the inner walls of the rubber hose connections. Sometimes a layer of the rubber, or fabric of the hose may loosen from the rest and the ragged end may obstruct the passage.
A sharp bend in a rubber hose may result in a “kink” and entirely close the opening.
The packing in a joint may swell, or a washer may not have the opening cut large enough, either case will result in a poor circulation.
Sediment is particularly liable to collect or form in a pocket, pipe elbow, or in the jacket opposite the pipe opening. Oil should be kept off of rubber hose connections as it will cause them to deteriorate rapidly, this may finally result in water circulation troubles. Rubber pipe joints between the engine and the radiator or tanks are advisable as they do not transmit the vibration of the engine, and hence reduce the strain on the piping. A strainer should be provided in order to reduce the amount of foreign material in the water.
Radiators. A clogged radiator will give the same results as a clogged jacket with the exception that steam will issue from the radiator if the circulation is not perfect.
If the radiator becomes warm over its entire surface it is evident that the water is circulating, the temperature being a rough index of the freedom of the water, or the interior condition of the surfaces. A leaking radiator may be temporarily repaired with a piece of chewing gum.
Should the radiator be hot and steaming at the top and remain cold at the bottom for a time, it shows that the water is not circulating and that the jackets on the cylinders are full of steam. Such a condition usually is indicative of clogging between the bottom of the radiator and pump, between the pump and bottom of cylinders, or of a defective pump.
Natural Gas Plant at Independence, Kansas. Used for Pumping Gas From the Wells to Various Distributing Points.
Thermo-syphon radiators are more susceptible to the effects of sediment and clogging than those circulated by pumps.
A radiator may fail to cool an engine because of a slipping or broken belt driving the fan, or on account of a loose pulley or defective belt tension adjuster. Keep the belt tight. The fan may stick on account of defective bearings.
Radiator may be AIR BOUND, due to pockets or bends in the piping holding the air.
Rotary Pump Defects. A defective circulating pump will cause overheating, as it will supply little if any water to the jackets.
Examine the clutch or coupling that drives the pump and see that the key or pin that fastens it to the shaft is in place. Next see that the driving pinion and gear are in mesh and properly keyed to their respective shafts.
In some cases the shaft has been twisted off, or the coupling pin sheared through by reason of the shaft rusting to the pump casing. Worn gears or impellers IN THE PUMP reduce the output and cause heating, as will a sheared driving pin in the impeller. Wear and bad impeller fits reduce the capacity of the pump.
Scale or sediment collecting in the pump sometimes strips the pins or impeller teeth. Note the condition of the gaskets or whether the pump shaft is receiving the proper amount of grease. Put a strainer in pump intake. See that no leak occurs on pump intake pipe.
To avoid the trouble and expense due to cracked water jackets, never neglect to drain the cylinders and piping from all water in freezing weather. Drain cocks should be provided at the lowest points in the water circulating system for this purpose. It would be well to provide an air cock at the highest point in the line in order that all of the water can drain out as soon as the drain cock is opened.
With automobile or portable engines it is not always convenient or possible to drain the engine every time that it is stopped and consequently we must resort to a “non-freezing” mixture or at least a solution that will not solidify under ordinary winter temperatures. Such a solution should be chosen with care, as many will cause the corrosion and destruction of the jackets and piping; NEVER USE COMMON SALT and water under any conditions.
Wood alcohol and water in equal parts, is often used for automobiles, but is rather expensive for portable engines having a comparatively great amount of water in circulation.
Unless the circulating system is absolutely air tight, as it is when radiators are used, alcohol will be lost by evaporation and must be replaced frequently.
The most practical solution for the average engine used, is made up by dissolving about five pounds of CALCIUM CHLORIDE in one gallon of water. This mixture will stand a temperature of about 15° F below zero, and if diluted to half the strength will not freeze above zero.
Use CALCIUM CHLORIDE, not ordinary Salt (Sodium Chloride).