A/T - RE4R01A, R4A-EL Premature Planetary Failure
TECHNICAL BULLETIN # 164TRANSMISSION: RE4R01A, R4A-EL
SUBJECT: PREMATURE PLANETARY FAILURE
APPLICATION: NISSAN, MAZDA
RE4R01A, R4A-EL Premature Planetary Failure
Several areas require extra attention when addressing a complaint of repeat or premature planetary failure on this unit:
# 1. Clogged or Restricted Coolers
# 2. Mislocated Case Bushings
# 3. Geartrain Set-Up
# 4. Lube-Relief Valve
# 5. Filter Restrictions
COOLERS
The transmission coolers in the vehicles listed below are of the "Fin" Type design. These fin type coolers will trap any contaminants in the fluid. Once the cooler is plugged or restricted with these contaminants, lube oil to the transmission will be reduced. The fin type coolers cannot be properly cleaned using conventional methods. Cooler replacement will be required if the cooler is clogged or restricted. Acceptable cooler flow is 1 quart in 20 seconds returning to the transmission.
These Nissan vehicles are originally equipped with fin type coolers:
MODEL YEAR
300ZX 1990-'92
Truck 1988-'92
Pathfinder 1988-'92
Mazda vehicles equipped with this transmission have not had any widespread cooler concerns.
PREMATURE PLANETARY FAILURE - CASE BUSHINGS
Mislocated case bushing will also cause planetary failure due to lack of lube. Lube oil is fed through the hole between the case bushings, and into the mainshaft. Make sure the bushings have not moved together, covering the hole.
PREMATURE PLANETARY FAILURE - GEARTRAIN SET-UP
To help the lube reach the front planet, remove the sun shell bushing. This allows lube oil to flow freely out the end of the sun gear into the front planet.
NEW replacement shells DO NOT have a bushing installed from the factory.
To prevent a potential loss of lube through clearance in the geartrain, limit end play to the minimum side of factory specifications. Listed below are the Nissan part numbers for the selective washers available.
Factory specifications on end play are:
PREMATURE PLANETARY FAILURE
LUBE RELIEF VALVE AND FILTER RESTRICTIONS
Lube Relief Valve
There is a lube blow-off ball & spring in the rear of the case that vents the lube circuit at approximately 17 psi. To test it for leaks, plug the hole between the case bushings and blow a 10-15 psi regulated air supply into the rear cooler line fitting. If the blow-off ball leaks, remove the ball, spring and orificed cup plug. Thread the hole and install an allen head set screw to plug the hole. Be sure to apply Locktite(R) to the threads of the set-screw during installation.
The life of the planetary in this unit depends on a free flowing filter to supply the lube circuit with an adequate volume of oil. A restricted filter will cause the pump to suck air which is eventually fed into the lube circuit. The filter can be restricted to the point that the unit doesn't exhibit any operational complaints but still not flow enough volume to supply the lube circuit sufficiently.
Take the extra time to thoroughly clean the valve body, and blow dust and stray fibers off new friction material. It may also be worthwhile to drop the pan and clean the filter after the vehicle has been in service for a week or two after overhaul. This will clean out any loose material that may have collected in the sump and on the filter during "break-in".