CONNECTING RODS.--A loose bolt in one of the connecting rods, while it may run along for a week or two, and cause no damage, is sure to cause trouble unless arrested. The moment the connection of a wire begins to loosen, it will never stop until it has severed the connection entirely. In taking apart an engine every part should be cleaned as it is removed, taking the utmost care of each pin, bolt, or nut. The walls of the cylinders should be examined, the piston rings tested and note whether they are worn. VALVES.--Then the valves need testing separately, and reground if there is the least indication of undue wear on one side more than on the other, or if there is the least carbon coating apparent. The best preparation for grinding them is a very fine emery, mixed with a heavy lubricant, to which should be added a small amount of kerosene. CAM-SHAFT.--When the cam-shaft is removed, note the marks, to see where they register with the marks on the cam shaft gears. Familiarize yourself with these details. THE CLEARANCE.--Particularly examine the clearance between the valve stem and plunger rod. If the clearance is too great, the exhaust valve will open too late. A small clearance is necessary to allow for the expansion of the valve stem. CLUTCHES.--Some clutches are so arranged that they may be removed as a whole; in others the separate parts may be taken out. If the latter appears worn, replace it at once. Do not wait until necessity compels you. Leather for this purpose should always be kept on hand, and the old leathers used as patterns for cutting the new. THE CLUTCH LEATHER.--When the leather wears down so the rivet heads are in contact with the metal surface, they should be taken out, and the leather countersunk, so that the new rivets will be deep enough to clear contact. This is something which, at the time you are examining the car, has not yet given any trouble, but the next day, if not attended to, the clutch may refuse to release itself quickly, and you are apt to wonder what the trouble may be. RIVETS IN THE LEATHER.--Keep the rivet heads free of metallic contact. This, and care in putting on the leather evenly will make a clutch that is sure to give you efficient service. If it does not grip quickly after the foot releases it, the spring is not at proper tension. On the other hand, the spring should not be too strong, and to push back the foot with too great force, because this will set the clutch, and give the car an unpleasant jerk. TRANSMISSION SYSTEM.--The transmission system should be examined at frequent intervals. The main thing is to note the ball bearings, and to remove old grease which has accumulated there. All ball bearings, however made, and applied, have more or less of a grinding effect. As a result, small particles of iron are cut off from the contact surfaces, which is indicated by the fact that the grease is discolored, or blackened.