Radiator Problems
Radiator or circulation insufficient, or water jacket too small. In this case radical changes would be required. Lime deposits must be guarded against.
Ignition Too Late.
An engine running under these conditions may get extremely hot. When the defect of knocking is inherent in an engine, one is inclined to diminish the advance, whereupon the
risk is incurred of the engine getting hot. It is better to leave the advance alone and close the throttle a little.
Fan Belt Stretched
Fan running too slowly. No way of escape for hot air inside of bonnet, etc. Examine these different features and correct them if necessary.
Influence of Carburetor
In summer, open cold air ports to Carburetor. In Airplanes or Racing Engines running at maximum power and speed over extended lengths of time, a lean mixture will cause overheating.
NOTE:-
It is sometimes observed that an engine seems to overheat more with one Carburetor than with another. Assuming that both have been properly adjusted, this may be due to the following causes:-
An engine does not generally get hot when running at high speed, the circulating pump and fan being most efficient under these conditions. Conversely, when the engine slows down in going uphill with full admission, the fan and pump are working more slowly and therefore with less efficiency. It follows, then, that the best Carburetor, ie: the one with a wide range at low speed under load, and allowing the engine to pull more readily when running uphill, will more readily show the imperfections of the cooling appliances.
TO SUM UP
Given fair "tuning up" of the Carburetor its influences on heating are of an indirect character.
BOTTOM PLUGS
FILTER PLUG
FILTER BODY
CHANNEL SCREWS
CAP JET
Fibre washers are fitted under each of these, and it may be found that these are defective, or that the part is not properly tightened up. In the case of the Filter Body it may happen that a strand
of wire from the Filter Screen has gotten between the gasket and the body and when the Filter Plug was tightened up this wire has cut a groove in the gasket. This can easily be rectified by
putting in a new gasket.
FLOODING CARBURETOR It is strongly recommended that the foregoing be carefully attended to before any attempt is made to change the level of the fuel in the Float Chamber. If, after careful inspection it is decided that the leakage is due to faulty action of the Float mechanism, proceed as follows:-
Remove Float and shake it to determine if any fuel has leaked into it. if such is the case, submerge the Float in hot water, the hotter the better, and the action of the heat will vaporize the fuel and it will seek escape at the point of leakage, at the same time showing where the leak is by the bubbles. In soldering up a leak in the Float be very sparing with both heat and solder - too much of the former may open the seams of the Float beyond repair, and too much of the latter will change the buoyancy of the Float or put it out of balance.
See that the Float Chamber is absolutely clean and that no small particles of dirt are secreted. Sometimes small particles of dirt will get under the Needle Valve and embed themselves in the Needle Valve Seat, this being the most common cause of Flooding carburetors. In any event press down on the Needle Valve and give it twisting motion with the fingers, alternately raising and lowering it as when grinding a valve in the cylinder. If this does not stop the leaking try holding the Needle Valve firmly on the seat with the fingers and gently tap it with a light wrench , raising and turning it occasionally. This will usually result in making a new seat for the valve and thus stop the leak.
Examine the valve lever weights. Under vibration the Float will revolve or oscillate about the Needle Valve and the bearing faces of the Lever Weights will become worn flat. When this wear goes so far the fuel will rise to the level of the jets and overflow before the valve is seated. If a decided flat surface is found on the Weights, reverse them, this operation bringing them back to the original point of adjustment. See if the needle valve is tight in the body also.