Before installing an oil pan or clean out plate in one of the earlier Model A cars or AA trucks, be sure to replace the oil pump retaining spring. This is very important. If the spring’ were omitted, it would allow the oil pump to drop down far enough to become disconnected from the oil pump shaft and this, of course, would cause the pump to fail to operate.
To eliminate any possibility of a mechanic failing to replace this spring, a change was made some time ago by attaching the spring to the end of the pump. This was done by means of a retaining clamp, as shown in Fig. 853.
However, in view of the number of cars manufactured prior to this change, mechanics must check each job on which they remove the oil pan or clean out plate to make certain they have replaced the pump spring.