There are three filter types for the AX4N, it is the seal that determines the correct one to use, (a short orange, a tall orange and a green seal, each having a different part number). The short orange is not used in the AX4N at all. The tall orange is used in the AX4SH and some AX4N with deep pans. The green seal is used in all other AX4N's and AX4S starting in 1996. A good guide is to replace the filter with the same seal.
Mercon V fluid is not the same as it's earlier versions, nor is it similar to earlier Dextron fluids.
A good video to watch is HERE. The filter that is being replaced is the older style and is replaced with the older style. A diagram can be found HERE.
The AX4N is an improved version of the basic AXOD, and is more reliable. This transaxle shifting is non-sequential (as indicated by the "N" in AX4N) and has improved shift quality over the previous AX4S. Although similar in design and dimensions, it is a different transaxle than previous AXOD transmissions. The AX4N has 19 bolts to retain the fluid pan. It was used in the 1996–99 Taurus SHO models, and was standard on Duratec-powered models. It also appears in some 1994–2002 Vulcan-powered models. It became standard with both engines in 2003. It was renamed the 4F50N in 2001.
Reliability issues
Earlier AXOD and AXOD-E models have a poor reliability record due to internal lubrication problems. These were mostly remedied by 1995. These transaxles require fluid and filter changes every 30,000 miles to maximize service life.
Intermediate clutch failures resulting in poor 1-2 shifts or slipping are common on all AX family members.
Failure of the "Neutral to Drive Accumulator" causes hard shifts into a drive gear (R, OD, D, 1) from "N" or "P". This can become quite violent. Reasons for this part's failure: Piston stuck, or seals or springs damaged or missing. Correction for this problem: Check these parts for damage. Replace as required (located inside the transaxle, recommended that a transmission shop do the repair, but a full rebuild of the transaxle is NOT required). In general, however, difficulty shifting from neutral to overdrive, OD to N, N to R, and R to N is most likely caused by a stretched shifter cable.
Other issues such as locking and/or breaking the parking "pawl" occurs in these transmissions primarily due to owner negligence in not operating the parking brake properly, or not using the parking brake at all. If the vehicle is allowed to "roll back" onto the pawl with heavy force (such as when parking on a steep incline), the pawl may break off or seize the gears so that either the vehicle rolls away, or when the owner starts the vehicle and attempts to put the vehicle in gear, they are unable to move the shift lever from Park. This creates a compound issue in which the shifter linkage or cable can break due to excess force. The vehicle's owner guide states the appropriate procedure is to engage the parking brake before shifting to Park, rather than relying on the pawl, as the pawl is a last line of defense to prevent the vehicle from moving unintentionally. If the parking pawl breaks off or bends, serious transaxle damage can occur.
Recently, NHTSA launched an investigation into the Ford Freestar and Mercury Monterey due to numerous complaints with regard to the equipped 4F50N transmission. Although the investigation is centered on the Torque Converter, these failures often require that the entire transaxle be rebuilt or replaced.
Some have found that adding a transmission fluid cooler to AX-equipped cars (i.e. the Taurus/Sable), can extend the transmission's life, as it significantly reduces the temperature of the transmission fluid. Coolers available from car parts websites are not too costly, and will pay for themselves if installed correctly. Shifting is also smoother with cooler fluid.
