The engine computer needs to know what the fuel mixture is with a high degree of precision so it can optimize fuel economy as well as emissions. If the information received by the powertrain control module (PCM) from its sensors is not accurate, it may command too much fuel or not enough.
A seal must always be installed so that the sealing lip is facing the fluid to be sealed. This is because the lip is made so that pressure applied to it from the "wet" side of the seal will tend to increase the pressure the lip applies to the shaft. If the seal is installed backwards, pressure acting on the "wrong" side of the lip will cause it to lift from the shaft, resulting in leakage. On most seals, the correct side is obvious; however, on others it is not.
Follow these tips to diagnose and fix a transmission fluid leak on several Ford, Lincoln and Mercury models.
Troutman, NC, technical program recognized as eighth-annual recipient of national award for automotive education excellence.