Few facts I discovered in the process:
- Nissan Pathfinder (Xterra, Navara...) transmission tend to color ATF very dark brown, but still smell more like new ATF, not burned. This seems to be quite normal if you use Nissan MAtic J or S ATF.
- It seems that there are two types of AT filters inside tranny. One with large wire mesh, and the one more like real filter with very dense filtering mesh. The latest might get changed during ATF change (if you drop the pan), but seems not mandatory.
- Full ATF flush vs. drain and refill...I've tried just drain and refill, but such a procedure rendered all given ATF very dark brown very soon, so I would recommend full ATF flush, of course, if ATF still does not smell burnt. Even Nissan OEM service manual does not prefer either, but gives instructions for both procedures.
- If you do it properly, you might pass with only 3-4 quarts (or liters) of excess flushed ATF, so it's not a real expense.
- When you buy ATF (I recommend only Nissan Matic J or S), buy 30-50% more than needed. Better 1 bottle more than 1 missing during procedure.
I had an intention to film & photo document the whole procedure, but unfortunately my Android cam died so there's no visual context
THE PRINCIPLE
The ATF circulates from AT oil pan via pump to transmission housing, there flows thorough torque converter, AT gearing system, then to cooler / heater inside main engine radiator and back to AT oil pan. By flushing essentially you intercept ATF flow just before it returns back to oil pan and drain it into separate container, while fresh ATF is feed into the system from AT oil pan.
HOW TO DO IT
1.) I suggest you drive the vehicle before procedure, so ATF warms up. It will flow nicely when hot.
2.) Remove ATF check plug in engine compartment. It has 10mm fixing bolt, unscrew it and pull the checking stick out:
3.) Lift the vehicle and secure it properly. Best to use some garage lift.
4.) Unscrew front metallic (1st from front) and plastic middle (3rd from front) underbody protection plates. This takes some dozen of 10mm bolts to unscrew, some might be rusty, so you can spray them with WD40 as a helper.
5.) Now you might mess a bit with front metallic protective plate, as it has some bolts on front side, but you would need to remove whole lotta plastic spoilers to get to those bolts. But as this metallic cover is quite thin, I decided to just pull it down a bit (ok, I deformed it, but it was deformed even before from off road abuse, so no big deal).
The purpose of this is to get easier access to ATF fluid hoses at the very bottom of main radiator.
6.) Time to drain ATF from AT oil pan drain plug. I think it's 17mm bolt. Put a catch pan under and remove drain plug. Some 4-5 quarts will get out.
Let it drain.
7.) Now see the radiator receptables. It has one or two BIG hoses attached at very sides, and two miniature receptables for ATF hoses few inches from each side:
8.) Looking towards DRIVING DIRECTION, the LEFT hose is cooler input, and the RIGHT hose is cooler output and this is what we'll attack. This RIGHT one goes back directly into AT oil pan, so here we'll intercept all dirty ATF, which is still left inside the system.
9.) Use plyers, squeeze and pull back the hose clamp few inches back from hose receptable area to the hose itself. When hose is free of clamp, do NOT just pull hose off the receptable, but rather gently but persistently try turning it left/right until it gives up. Only then pull it off.
ATF will start dripping and it will take some time until it stops. Don't wait, just make sure you have a pan to catch that dirty ATF (maybe 1-2 quarts/liters will pour through that hose and radiator receptable)
Let it drip.
10.) As per image above, get some 4-5 feet (1,5m) long hose and attach it to radiator receptable. Put the other end into an old oil can and fix it with tape or something, so it won't get out by itself.
11.) Now remove AT oil pan. Dozens of 10mm bolts to unscrew, not using some force to undo them. Keep one screw in front and back to the last and be careful not to twist oil pan when removing.
Maybe best you put drain plug temporarily back in, because some ATF will be there in pan after removing, so it's easier for you to carry it around with drain plug inserted.
12.) Most probably the GASKET will stick to oil pan and not to AT housing.
13.) Now EXAMINE THE DIRT in removed oil pan:
- some METAL shredding on magnets is normal wear and tear. Say, like 1mm thick metal "pasta" on magnets...that's normal.
- the bottom of the pan may have some sludge in form of spray-thin dark coloured layer. That's normal.
- NO pieces of any kind should be present! Nor metallic not any other material. If you find anything worth mentioning in oil pan, that might be indicator of excessive wear, broken parts or shredded coupling plates. VISIT TRANNY DOCTOR in that case!
14.) If everything OK, remove magnets from pan (they are just magnets, holding to metal pan), wash and clean everything precisely, until fresh white paper towel does not pick any dirt anymore. MAKE SURE you wash and wipe it dry and not leave any cleaning agent on the surface!
You can use Brake Cleaner.
15.) This step is my own invention, not sure if it's perfect, but seems OK. I use Brake Cleaner or Isopropyl Alcohol (rubbing alcohol) and fresh microfiber cloths to wash accessible AT bottom surfaces of GRAY deposits. There is a thin layer of grey deposits on AT filter and some components, which I carefully spray with brake cleaner and wipe carefully deposits off.
But be very careful not to spray too much into AT housing and especially NOT INTO ATF FILTER, as brake cleaner might not evaporate fully and this is definitely NOT what you want to be circulating inside your AT.
16.) LET IT DRY, DRIP, WIPE from time to time. IT left it open for at least 1 hour to be sure all solvents evaporated.
17.) While waiting, you may CUT old gasket off of the oil pan. One good method is to use utility knife with blade extended appr. 1-2 inches.
Do NOT scrape gasket layering surface - rather put knife blade inline with it and CUT it off by following the metal surface. Keep the blade all the time parallel to metal surface and just keep cutting gasket off. Sometimes it will go off in whole, sometimes in layers. Try not to cut metal pan surface too often or too deep.
When gasket is off, use brake cleaner and towel to wipe off any remains.
18.) Now you have dry and clean oil pan. Put new gasket and align holes BEFORE you approach remounting, because you might easily tear new gasket trying to align it during montage.
Do NOT use any oil under gasket.
19.) Just before you push fresh pan and gasket back to AT housing, wipe again the AT gasket surface with clean towel, so you will mount on DRY surface.
20.) Align holes and begin putting back screws. First just start ALL screws and make sure, that you put back 3 screws with holders for wiring properly. Do not tighten them, until you've got all started - gasket might misalign slightly and you don't want to ruin your new gasket due to rush.
21.) Now begin tightening them in cross-pattern, but DO NOT TIGHTEN THEM TOO MUCH! More like easy tugging them with a light force, as screwdriver would allow, not more.
22.) Ok, lower the vehicle, taking care not to bump your old oil catch can with temporary hose from ATF cooler outlet.
23.) Now boring part: pour at least 5 quarts (up to 10 quarts) of fresh ATF through dipstick hole. If you use plastic hose with small funnel, THIS CAN TAKE AN HOUR OR MORE! Try assembling some larger funnel and use longer filling hose, so gravity will work for you. Also you might preheat ATF bottles by putting them into warm water befor use; just make sure they are all tightly closed. But still it might take ages.
I use only genuine Nissan Matic J (or better S), regardless of any opinion here or elsewhere.
24.) Now it's time to start your engine.
For this step it's best to have helping hand, a friend to watch the temporary outlet hose, flowing into your waste oil container.
Start engine and put into NEUTRAL. Some 20-60 seconds it will take for the fresh ATF to start blowing through temporary hose into waste oil can.
Make your friend to give a signal to STOP THE ENGINE as soon as any of the following occurs:
- either waste oil can is full
- or fresh new ATF starts going out, that's perfect!
- or foamy ATF starts going out, that's a sign of low ATF level
25.) Stop the engine.
26.) MEASURE the quantity of old blown out ATF, so you will know how much ATF there is in tranny. Don't guess here!
For my AT approx. 9 quarts of ATF is in the system, so I stop when calculation shows that I poured in approx. 7 quarts of ATF.
27.) Now, raise your vehicle again and remove temporary drain hose from cooler. Reinstall original hose and clamp it properly back.
Make sure hose sits in prescribed plastic holders.
28.) Reinstall front and middle underhood protecting plates.
If you twisted front metallic plate for easier access, make sure you SKEW IT BACK, because you don't want the deformed protective plate to touch the radiator.
29.) Start the engine and shift through gears.
Check ATF level with dipstick. You should be somewhere in COLD area (usually between cut-marks on stick). The HOT level is usually marked with cross-hatched pattern on the stick.
30.) Check for leaks and you are good to go.
Hope this helps somebody
