7 Speed Auto transmission fluid change (Skyline, Q50, Q60, Fuga, Q70, A62 Titan and probably heaps of others including Navara...)

[Duncan]

I thought I'd do a write up on an auto transmission fluid change for a the nissan 7 speed Automatic. At some stage the genius engineers decided that the fluid in the trans was "for the life of the transmission", (which seems kind of self supporting to me) and removed the dip stick and fill tube (funnily enough there is still a casting for it).

Anyway, for this job you do need 2 specialist tools in addition to regular hand tools, jack and 4 good chassis stands.

You need a way to pump fluid up to the transmission; I got one of these but there are plenty of other options:

https://www.ebay.com.au/itm/364584087070

Don't trust the generic listing though, it does not come with the required adapter for the Nissan 7 Speed.

You need one of these, can't do the job without it:

https://navarapart.com.au/product/genuine-nissan-patrol-y62-d23-np300-navara-re7-dipstick-fill-connector1

You need a heap of compatible transmission oil. Could be Nissan, could be anything else rated for Nissan Matic S. You need at least 10 litres, I had 15 to give it a better flush...

Also, you need some biiig oil catch trays, at least one of these, or bigger if possible (volume was fine, size was very marginal):

https://autobarn.com.au/ab/Autobarn-Category/Tools-%26-Garage/Specialty-Tools/Oil-Service/Garage-Tough-Oil-Drain-Pan-Black-16L---GT1068/p/TO03191

Finally, a measuring jug is very useful if your pump does not have volumes marked on it, I got a 6l one:

https://www.repco.com.au/oils-fluids/fluid-accessories/measuring-jugs/penrite-measuring-jug-6l-pmj006/p/A5322648

Oh, and gloves.....this stuff is horrible (not as bad as diff oil, but getting there)

....First, jack up your car.....

[Duncan]

So, I'm not going to cover jacking up the car in detail, as I was using a quickjack, plus it will change per chassis you are working on.

The main thing is to get the car high, level and stable, so take your time and find good spots for the stand. You are going to spend a lot of time working right under the middle of the car. If you have a hoist, or access to one, you are laughing.

First you need to remove the transmission undertray. At the rear there are 2x 14mm headed bolts to undo. Unlike (apparently) the USDM model, you can easily get at both without the exhaust being in the way. While you can undo the undertray end of the bracket on one side (2x10mm head bolts), the other side is rivetted on so you can only undo the chassis side.

At the front there are 2x 10mm headed bolts then the undertray slides backwards from under the mid tray, and out of the way.

[Duncan]

OK....now the mess starts.

At the rear of the transmission is a 17mm drain plug. Put the oil pan under and remove the plug, you should get about 3 litres of fluid out (this is the pan capacity). I forgot to take a pic of the plug, so here is a marked up one I stole. 

Drain on the left (17mm) and fill on the right (in hex)

I got about 3 litres from the drain plug, and even with 75,000klm (and 2 track days), it really looked like it needed a change.

[Duncan]

If you are going the simple route, this is all you need to do on the draining side.

Just keep in mind that you are only replacing 30% of the fluid with each "spill and fill" - 3 litres in and the workshop manual says system capacity is 10 litres, and it recommends doing it 3 times.

I can't do maths but chatgpt tells me it can, this is what % new fluid you have after each 3 litre flush:

So you can see, you need 20 litres+ and 7 cycles if you want to get to 90%+ new fluid in the trans....slow and expensive!

[Duncan]

OK, so if you are either going for the bigger fluid change or are changing the valve body which includes the Transmission Control Module (TCM), first you should have both a new gasket 31397-1XJ0A and a torque wrench that can work down to 8Nm (very low, probably a 1/4 drive one). You can probably get by without either, but I really didn't want to pull it all apart together due to a leak.

First, you now need that big oil pan. The transmission pan is 450 long x 350 wide, and it will probably leak on all sides, so get ready for a mess.

There are 24x 6mm headed bolts holding the pan on. I undid the 2 rear corners, then screwed those bolts back in a couple of turns to let the pan go low at that end, then removed all the middle bolts on each side. Then, undo the front corner bolts slowly while holding the pan up, and 80% of the fluid will head out the rear.

From there, remove the remaining bolts and the pan is off.

You can see it is still dripping oil absolutely everywhere...it dripped all night....

I got another couple of litres when I removed the pan, and then another few when I removed the valve body - all up another 4l on top of the 3 already dropped in step 1.

[Duncan]

OK, Step 3, if you need to remove the valve body, either to replace it, the TCM, or to do a more complete drain. 

First, you need to disconnect the TCM input wires, they are about half way up the transmission on the drivers side. One plug and the wires are out of the way, but there is also a spring clip that stops the socket from sliding back into the transmission. On my car the spring clip was easy to get, but the socket was really stuck in the o-ring of the transmission housing and took some.....persuasion.

You can see both the plug to remove (first) and the spring clip (second) in this pic

Incidentally, right next to the plug, you can see where the casting has allowance for a dispstick/filler which Nissan decided not to provide. there is a cap held on with a 6mm head bolt that you can remove to overfill it (AMS recommend a 1.5l overfill).

Final step before the big mess, remove the speed sensor that is clipped to the valve body at the rear of the box. 

Then removal of the Valve Body. For this the USDM Q50 workshop manual has a critical diagram:

There are a billion bolts visible. Almost all of them do not need to be removed, just the 14 shown on the diagram. Even so, I both removed one extra, and didn't check which length bolt came from which location (more on that later....).

Again it is worth undoing the 4 corners first, but leaving them a couple of turns in to hold the unit up....gravity is not your friend here and trans oil will be going everywhere. Once the corners are loose but still in remove all the other 10 bolts, then hold the valve body up with 1 hand while removing the final 4. Then, everything just comes free easily, or like in my case you start swearing because that plug is stuck in the casing.

Done, the valve body and TCM are out

[Duncan]

A couple of notes about the TCM.

Firstly, it is integrated into the valve body. If you need to replace the TCM for any reason you are following the procedure above

The seppos say these fail all the time. I haven't seen or heard of one on here or locally, but that doesn't mean it can't happen.

Finally, Ecutek are now offering tuning for the 7 speed TCM. It is basically like ECU tuning in that you have to buy a license for the computer, and then known parameters can be reset. This is all very new and at the moment they are focussing on more aggressive gear holding in sports or sports+ mode, 2 gear launches for drag racing etc. It doesn't seem to affect shift speed like you can on some transmissions. Importantly for me, by having controllable shift points you can now raise the shift point as well as the ECU rev limit, together allowing it to rev a little higher when that is useful.

In manual mode, my car shifts up automatically regardless of what I do which is good (because I don't have to worry about it) but bad (because I can't choose to rev a little higher when convenient).  TCMs can only be tuned from late 2016 onwards, and mine is apparently not one of those although the car build date was August 2016 (presumably a batch of ADM cars were done together, so this will probably be the situation for most ADM cars). No idea about JDM cars, and I'm looking into importing a later model valve body I can swap in.

This is the top of my TCM

A couple of numbers but no part number.

Amayama can't find my specific car but it does say the following for Asia-RHD (interestingly, all out of stock....):

So it looks like programable TCM are probably post September 2018 for "Asia RHD". When I read my part number out from Ecutek it was 31705-75X6D which did not match Amayama for my build date (Aug-2016)

[Duncan]

One other thing to mention from my car before we reassemble and refill.

Per that earlier diagram,

 

There should be 2x B length (40mm) and 6x C length (54mm).

So I had incorrectly removed one extra bolt, which I assume was 40mm, but even so I have 4x B and 5x C.  Either, the factory made an assembly error (very unlikely), or someone had been in there before me. I vote for the latter because the TCM part number doesn't match my build date, I suspect the TCM was changed under warranty.

This indeed led to much unbolting, rebolting, checking, measuring and swearing under the car....

In the end I left out 1x B bolt and put in a 54mm M6 bolt I already had to make sure it was all correct

[Duncan]

OK, so regardless of whether you did

Step 1 - Spill

Step 2 - Trans pan removal

Step 3 - TCM removal

we are on to the clean and refill.

First, have a good look at the oil pan. While you might see dirty oil and some carbony build up (I did), what you don't want to see is any metal particles on the magnets, or sparkles in the oil (thankfully not).

Give it all a good clean, particularly the magnets, and put the new gasket on if you have one (or, just cross your fingers)

Replacement of the Valve body (if you removed it) is the "reverse of assembly". Thread the electrical socket back up through the trans case, hold the valve body up and put in the bolts you removed, with the correct lengths in the correct locations

Torque for the bolts in 8Nm only so I hope you have that torque wrench handy (it feels really loose).

Plug the output speed sensor back in and clip the wiring into the 2 clips, replace the spring clip on the TCM socket and plug it back into the car loom.

For the pan, the workshop manual states the following order:

Again, the torque is 8Nm only.

[Duncan]

OK, onto filling.

So I don't really have any pics, but will describe the process as best I can. The USDM workshop manual also covers it from TM-285 onwards.

First, make sure the drain plug (17mm) is snug. Not too tight yet because it is coming off again. Note it does have a copper washer that you could replace or anneal (heat up with a blow torch) to seal nicely.

Remove the fill plug, which has an inhex (I think it was 6mm but didn't check). Then, screw in the fill fitting, making sure it has a suitable o-ring (mine came without but I think it is meant to be supplied). It is important that you only screw it in hand tight.

I didn't get a good pic of it, but the fill plug leads to a tube about 70mm long inside the transmission. This sets the factory level for fluid in the trans (above the join line for the pan!) and will take about 3l to fill.

You then need to connect your fluid pump to the fitting via a hose, and pump in whatever amount of fluid you removed (maybe 3 litres, in my case 7 litres). If you put in more than 3l, it will spill out when you remove the fitting, so do quickly and with a drain pan underneath.

Once you have pumped in the required amount of clean ATF, you start the engine and run it for 3 minutes to let the fluid circulate. Don't run it longer and if possible check the fluid temp is under 40oC (Ecutek shows Auto Trans Fluid temp now, or you could use an infrared temp gun on the bottom of the pan). The manual stresses the bit about fluid temperature because it expands when hot an might result in an underfil.

So from here, the factory manual says to do the "spill and fill" again, and I did. That is, put an oil pan under the drain plug and undo it with a 17mm spanner, then watch your expensive fluid fall back out again, you should get about 3 litres.  Then, put the drain plug back in, pump 3 litres back in through the fill plug with the fitting and pump, disconnect the fill fitting and replace the fill plug, start the car and run for another 3 minutes (making sure the temp is still under 40oC).

The manual then asks for a 3rd "spill and fill" just like above. I also did that and so had put 13l in by now.  This time they want you to keep the engine running and run the transmission through R and D (I hope the wheels are still off the ground!) for a while, and allow the trans temp to get to 40oC, then engine off.

Finally, back under the car and undo the fill plug to let the overfill drain out; it will stop running when fluid is at the top of the levelling tube.

According to the factory, that is job done!

Post that, I reconnected the fill fitting and pumped in an extra 0.5l. AMS says 1.5l overfill is safe, but I started with less to see how it goes, I will add another 1.0 litres later if I'm still not happy with the hot shifts.

[Duncan]

So, that is it!

It is a pretty expensive process with the ATF costing 50-100 per 5 litres, and a mechanic will probably charge plenty because they don't want to do it. Still, considering how dirty my fluid was at 120,000klm I think it would be worth doing more like every 80,000 to keep the trans happy, they are very expensive to replace.

The job is not that hard if you have the specialist tools so you can save a bit of money and do it yourself!

[joshuaho96]

I did basically the same procedure on a ZF6HP but the reason to pull the valve body is to replace the seals between the valve body and the transmission which are notorious for leaking pressure with age causing poor shifting and burning out the clutches. If you just wanted to exchange all the fluid you should be able to undo one of the transmission cooler return lines to drain into a bucket while using the pressure filler to keep it topped off. 

[Duncan]

1 hour ago, joshuaho96 said:

I did basically the same procedure on a ZF6HP but the reason to pull the valve body is to replace the seals between the valve body and the transmission which are notorious for leaking pressure with age causing poor shifting and burning out the clutches. If you just wanted to exchange all the fluid you should be able to undo one of the transmission cooler return lines to drain into a bucket while using the pressure filler to keep it topped off. 

So...I thought about that (muuuuuch easier!) but I wasn't confident running the pump dry by doing that....is it safe?

[joshuaho96]

7 minutes ago, Duncan said:

So...I thought about that (muuuuuch easier!) but I wasn't confident running the pump dry by doing that....is it safe?

You have to continuously fill it to avoid dry running. Personally the transmissions I've serviced have never been bad enough to justify doing this because it is definitely a pretty complicated and somewhat risky procedure compared to simply draining the pan, measuring what came out, then refilling with the exact same amount.