How To Diagnose a Ford FMX Transmission Problem

by John Stevens J.D.

The Ford FMX automatic transmission is a three-speed unit first introduced in 1950. As the transmission is used, the internal components of the transmission wear. Eventually, the transmission will require repairs or replacement. Thankfully, the FMX transmission rarely fails without any warning. Knowing what to look for can allow a targeted repair plan and, in many cases, time to prepare for the expenses associated with a repair or replacement. Follow the steps below to diagnose a Ford FMX transmission problem.

Inspect the transmission fluid at the tip of the transmission dipstick for discoloration or debris. The FMX dipstick is located under the hood on the passenger's side of the vehicle and can be removed by simply pulling the dipstick. The color of the transmission fluid should be a light red color. If the color of the fluid is brown or dark red, this indicates that a band has failed from overheating. If the fluid is foamy, this indicates either that there is too much fluid inside the transmission or that there is an internal air leak. If the fluid contains debris, this indicates the existence of defective bearings, bands or clutch packs.

Shift the transmission into gear with the vehicle at rest and with the engine running. If the initial engagement is rough, this indicates either that the idle speed is too low, the vacuum unit or tube is broken or that the front band needs to be replaced.

Shift the transmission through all of its gears while depressing the brake pedal with the emergency brake engaged. If the transmission will not shift into certain gears, there is a good chance that the valve body, linkage or either the front or rear servomechanism needs attention. There also exists the possibility that the transmission does not have enough fluid in it. The fluid at the tip of the dipstick should be between the "Full" and "Add" marks located at the end of the dipstick.

Determine whether smoke exits from the transmission by operating the vehicle until it reaches normal operating temperature. If smoke is present, the transmission is overheating. This is likely caused by a problem with the oil cooler or the cooler's connections, a faulty pressure regulator or a worn converter clutch.

About the Author

John Stevens has been a writer for various websites since 2008. He holds an Associate of Science in administration of justice from Riverside Community College, a Bachelor of Arts in criminal justice from California State University, San Bernardino, and a Juris Doctor from Whittier Law School. Stevens is a lawyer and licensed real-estate broker.