Here’s a quick “How-to” for changing out the transmission fluid, filter and pan gasket for a 2001 2WD automatic transmission Pathfinder. This will apply to most other Pathfinders and QX4’s as well.
If you have previously done a pan drop and would prefer a more efficient method of exchanging the fluid, either use the drain plug to drain & fill the pan (approximate drain & fill capacity is 3.5 quarts), or do a cooler line fluid exchange (see steps in the “Transmission and Driveline” section of Pathfinder QX4 General Information Article to change all of the fluid.
In my opinion, one pan drop in the vehicle’s lifetime is sufficient, especially if an in-line transmission filter is installed (see the bottom of this article for details). An automatic transmission generates 75% of its lifetime wear within the first 10,000 miles due to break-in wear and stuff left over from the manufacturing process, and some of it will settle in the bottom of the transmission pan and be collected by the in-pan magnet; thus, one pan drop is sufficient.
- 19mm socket (for transmission drain plug)
- 10mm socket (for pan and filter bolts)
- Torque wrench (preferably two; one for foot-pounds and one for inch-pounds)
- Pan for catching oil
- Mechanic’s dolly / creeper
- Pneumatic ratchet (for quick disassembly, but not necessary)
- 6 quarts of automatic transmission fluid, preferably Nissan Matic D. I used Royal Purple Max ATF in this case
- Pan gasket
- 18 self sealing pan bolts (optional, but recommended; the old ones are reusable, just clean them off with brake cleaner)
- Petroleum jelly (optional; FSM says to apply petroleum jelly to the filter O-ring before installing)
- Brake cleaner
- Gasket scraper
- New drain plug crush washer [11026-01M02] DRAIN PLUG WASHER
Part numbers for OEM parts:
- [31728-41X03] OIL STRAINER
- [31713E-41X07] SEAL-O RING
- [31397-41X05] GASKET-OIL
- [31377-41X06] BOLT (quantity: 18)
If you would prefer an aftermarket filter, gasket, and O-ring kit, I recommend this Beck/Arnley kit.
Step 1: Remove the drain plug and let the majority of the oil drain into pan.
Step 2: Remove the 2 10mm middle front bolts that secure the oil cooler tube brackets.
Step 3: Remove all other bolts, except for the one in the opposite corner of the drain plug. Loosen that last one so the pan will tilt towards the drain plug and the last of the oil will flow out.
Step 4: Remove that last bolt and drop the pan.
Step 5: Clean the pan of all remaining oil and any traces of the old gasket using brake cleaner and a gasket scraper – be sure not to scratch the gasket mating surface of the pan!
Step 6: Reinstall the drain plug with 22 – 29 ft-lbs of torque. Replace the crush washer with the new one.
Step 7: Remove the magnet from the pan and clean off any metal shrapnel with brake cleaner and paper towels. Mine was shrapnel free.
Step 8: Remove the 4 bolts holding up the old filter.
Step 9: Install the new filter using 61 – 78 inch pounds of torque. Make sure the O-ring is installed before installing it; apply petroleum jelly to the O-ring before installing.
Step 10: Reinstall the transmission pan; use the new gasket and new self-sealing pan bolts. Torque the pan bolts to 61 – 78 inch lbs.
Step 11: Add the same amount of oil that was drained. Use the transmission dipstick tube to add the oil. Generally the drain and fill capacity is about 3.5 quarts, but since we dropped the pan it’s probably closer to 4. Six quarts of fluid is recommended as a safety margin.
Step 12: Set the parking brake, start the vehicle and check for leaks. Let the engine idle for five minutes.
Step 13: Check the transmission fluid level, and add fluid if required:
To check the fluid level:
1. Park on a level surface and apply the parking brake.
2. With P selected, shift through every gear and return to P.
3. Pull the transmission dipstick with the engine idling, wipe it clean, reinsert it completely, and read the level. It must be within the area labeled “COLD”.
Step 14: Check the fluid level and the pan area for leaks over the next few days. Check the fluid level hot, preferably; use the same steps as described above, but ensure the fluid is within the notched area labelled “HOT”. Add fluid as required.
After doing this I noticed a massive improvement in the smoothness of shifting.
As a side note, I highly recommend using a set of ramps. I bought some used ones off eBay and just sanded them down and repainted them. These made life much easier. I also used TransTune by SeaFoam as a transmission treatment before performing this. I’m not sure if it helped but it sure didn’t hurt.
New filter and pan gasket
New filter O-ring
4 bolts that secure the filter
New filter installed
I went to my local Nissan dealership and bought 18 self-sealing pan bolts. I expected them to be longer.
Transmission dipstick tube, located on the passenger side of the engine; use this to fill
Ramps before new paint
Installation of a Magnefine in-line transmission filter on the transmission cooler return line is also highly recommended. The Magnefine contains a very strong magnet to catch all ferrous wear material, and filtering media in the range of 35 microns to catch anything non-ferrous. Install one on the power steering return line too to significantly prolong the usable life of the power steering fluid. A 3/8″ Magnefine will fit both the transmission and power steering hoses. See a Magnefine filter in use for 23,000 miles opened here. The transmission cooler return line is located on the passenger side, and the power steering return hose is connected to the tube on the side of the power steering fluid reservior.
If you have questions or comments, here’s a discussion of this article! How to: Change Transmission Fluid and Filter on a Pathfinder / QX4