PSA [Peugeot & Citroën] AL4

Transmission general data

The French automaker PSA (Peugeot Citroen Association) in collaboration with Renault launched the mass-production of the 4-speed automatic transmission DP0 (also named as AL4) in 1999. The automatic transmission AL4 is intended for a FWD vehicles with engines from 1,4 up to 2 liters. The automatic transmission AL4-DP0 is a unique and successful solution of French engineers. The design of this transmission is very simple and well-balanced according to the principle «nothing extra».

Technical issues and repair guidelines

The DP0 unit has a heat exchanger for oil cooling. All transmissions with the heat exchanger operate at a temperature close to critical. In summer time, the DP0 regularly overheats and has some problems with the electrical components, namely with the valve body. It is a constructive peculiarity of many automatic transmissions with the heat exchanger. After running 80 thousand kilometers its up to the auto owner to preserve this transmission from overheating. Friction components contaminate ATF, the dirt settles in the heat exchanger (which also operates as a filter) and as a result after critical contamination of the heat exchanger the oil does not have time to cool in case of the hot weather. Therefore, the valve body (and solenoids) start operating improperly. The more contaminated becomes the fluid, the higher the operating temperature and the lower efficiency of the valve body.

The resource of this transmission before the overhaul (under the condition of careful and proper usage) may reach 150-200 thousand kilometers after well-timed repair procedures with reassembly and replacement of spare parts. After these procedures the transmsision resource may be prolonged up to 500 thousand kilometers.

Soft spots of PD0

EPC and TCC solenoids are the most frequently replaced components of the DP0 transmission. Worn bushings are also often replaced by transmission specialists. The wear-out of bushings leads to the following chain reaction: bushings start leaking, packages do not have enough oil and the computer forces the ЕРС solenoid to open the channel to the full cross section, the pump operates under maximum load and the EPC solenoid rapidly wears. The operation with fluid shortage has a bad impact on friction components of the corresponding package. The valve body is a typical area for repair. The valve body is very sensitive to overheating and contaminated ATF. Overheating changes the metal plate geometry, valves wedge and springs become overloaded until they break down.

Oil losses through worn-out joints lead to the pressure drop in the line, slipping and burning of friction components. The wear-out of one-sided friction discs occurs evenly, therefore all friction discs are replaced during the overhaul. Specialists recommend to replace Teflon rings of the rear cover. Brake bands (the pair F2 and F3) are replaced in the process of each overhaul of the transmission with burnt ATF. Servo pistons are replaced together with brake bands. The damaged pump cup (seal) is the most popular part for repair among seals and sealing strips. One of the most common problems takes place in the needle bearing located between the hub 570 and drum 554 in the Е2 package . The clutch package E2 (4th) is the most popular part for replacement among spare parts.