HOT MOTOR.

Auckland Star, Volume LXVI, Issue 130, 4 June 1935, Page 16

HOT MOTOR.

VARIETY OF CAUSES

POINTS TO "WATCH. UNMISTAKABLE SYMPTOMS. Signs of the engine overheating are unmistakable. Waves of hot funics drift into the car interior; the water in the radiator tends to boil; the performance falls away and a general unpleasant atmosphere pervades the car. The cause? It may. be one or more of the following, which is a reasonable order in which to investigate the trouble. The radiator—short of water due to leakage past the joints, or need for normal topping up. The radiator honeycomb may be with mud or road dirt, and should be cleaned with a strong water jet directed from the inside of the bonnet and not vice verea. A furred up radiator cooling system is frequently the cause of overheating on an older car owing to the deposits from the water. These can be cleared out with special preparation. A badly furred up system may need a new honeycomb.

The fail—this may not work efficiently owing to a slack belt, which may affect also the impeller (if a common drive is used) so that the water is not pumped around quickly enough to meet the requirements of the engine. The fan blades might with advantage take a little more twist to increase the suction of air through the honeycomb.

Engine oil—make sure that the sump is not short of lubricant (a frequent cause of overheating), which may lead to partial bearing seizure, accentuating the signs of overheating. Ignition retarded —indicated by a sluggish performance and may be due to a stuck-up automatic governor control or seized manual control. Check the contact breaker gap, also sparking plug gaps, at the same time. ' Carburation — mixture too weak, caused by partial stoppage of the jets or due to a floating obstruction in the petrol pipe limiting the supply of fuel passing through. Clean the jets and blow out the pipe line. Make sure the pump is working properly. If the pipe line or pump be near the exhaust pipe, the heat may cause partial vaporising before the fuel reaches the carburetter; insulate the pipe with asbestos."

Valves stuck up —shown by poor compression, difficult starting, and no power from the engine. The unseated valves cause air leaks, weakening the mixture which burns with much greater heat than one of correct proportions. It may be caused by carbon or congealed oil around the valve stem which can sometimes be cleared away with a -mixture of engine oil and petrol squirted into the air intake of the carburetter when the engine is revving at about 1000 r;p.m. Carbon under valve seats is also troublesome. It is advisable to dismantle, clean up, and grind in all the valves thoroughly. See that the joints are properly remade. Air leaks—apart from valve trouble, may be caused by bad manifold joints, worn throttle spindle, leakage past the pistons, and so on. Joints should be remade with new gaskets and a good compound. Leaks past the pistons can be cured (if not too bad) by new rings.

Brakes binding — owing to incorrect, adjustment the brakes may tend to bind and continual rubbing will increase friction eo that the retarding effect increases and gives the engine a heavier load to pull. If no other causes of overheating can be traced, feel the brake drums for heat and test the free running of the car.