DIY'ing 7A trans fluid, need advice!

SG4247

I have done that on other cars. But, you can pick up an infared laser temp gun at OReilly or other autoparts stores for cheap.

Just shoot the trans pan with the laser in 3 or 4 places with the car level, to get the temp, and fluid level correct.

qtrskills

Here is my experience with fluid change on the 7at:

I used Assenmacher ATF 180 adapter, fluid hand pump and IR thermometer of Amazon.
I dropped the oil pan and swapped it for another one that I bunged temp sensor and defi gauge into so I can monitor my tans temps at the track so that's how the fluid was drained. Then the mechanic filled it and drained it 3 times while the engine was off. I drove for awhile and noticed the car jerked when I came to stop from a hard braking. Obviously, the tranny was low on fluid because when it was filled the torque converter was at a standstill. We redid the procedure, however, this time the car was already at operating temp (fluid at 80-90C). Left the shop and still had the problem which indicated that I was still low on fluid. The third time I parked the car at the shop at night so it would cool down and started working on it the next morning. Turned it on, put it on the lift while running in neutral, pumped more fluid till it was full closed the fill port, monitored the pan temp with an infrared thermal gun of amazon till it reached about 35c that's when we reopened the fill and refilled it till it started dripping all while cycling through gears (5secs in each from P to D), when the fluid started to drip we closed the fill port.

What I learned:
*Trans fluid is affected a lot by temperature. I remember seeing a graph somewhere that showed the volume by the temp of the fluid. You should start after your car has cooled down.
*The car has to be relatively level.
*The cycle of filling and draining 3 times is mainly done to guarantee the fluid was completely changed everywhere in the tranny not only the fluid in the pan.
*Fluid temp in stock 7at almost matches the oil temp. I have 25-row Setrab 6 series on my car running with the stock in-radiator cooler and my fluid runs about 15-20c cooler than my engines oil temp. So at the track, I pull off when my oil temps are high and I don't have to worry about my trans fluid.

Sorry for the long read lol hope it helps

qtrskills

Here is a good read that helped me

https://www.myg37.com/forums/d-i-y-i...rop-clean.html

Also, download the service manual check part TM page 316-318

B&W_Evader

May take more than 2 exchanges before the fluid looks clean.
There is no way stealership is only going to charge $100 for this.
I have a vacuum pump and a 4"x48" ABS pipe with caps on both sides as reservoir. That sucker can hold a lot of fluid.
and... have not done this on a Z (mine's a 6-spd) but have on other vehicles.

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AstatenateZ

Did you read my post? Lol my dealership has never done one. I have a tech friend at Nissan who said no one there is comfortable doing it and it hasn’t been done. They can’t hook their exchanger machine to it. So they’d be using a hand pump (same thing I’ll be using) and lastly they don’t have the part to do a fill. The charge pipe or whatever it’s called.

FPenvy

ah gotcha i missed that tid bit. my bad.

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AstatenateZ

Ok talked to my mechanic friend who’s house I’m gonna do it in, I'll do the initial drain and fill with slightly more than what came out. Drive it to get fluid in all gears. And then when I drain it the second time, I’ll let it cool off, I’ll add what came out, and measure trans temp with infrared (he said he has one) and then as soon as it stops overfilling out of the drain plug at 104 degrees it means it’s at the proper level? Or once is stops overfilling out of the filler plug at 104 degrees it’s at properly level?


Okay I’ll do the initial drain and fill up with tiny bit more than what comes out. My second time doing it, I’ll let car cool off. Drain again and fill up. Until it flows out of drain hole or filler hole at 104 degrees???

AstatenateZ

This is the info I have. I guess I will measure temp (on the second drain to make sure it’s proper)


So my new list is 1) jack car up, get level
2) drain fluid and measure what come see out
3) add new fluid (slightly more than what comes out)
4) drive it thru all 7 gears.
5) come back , jack it up level again
6) let it cool off
7) drain & refill what comes out
8) hit trans pan 3-4 places with infrared gun to check til it’s between 95-113 degrees roughly 104 degrees. Once close to 104 degrees I’ll unplug filler plug and once it starts to barely drip out at proper temp I’ll reinstall plug (like I did with my rear diff) and go test drive it.

Am I good on this?

AstatenateZ

No prob it was kinda long I didn’t expect everyone to read ALL of it lol

FPenvy

yeaaaaa i saw multiple lines and just said nahhhhh i get the idea here lol

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AstatenateZ

I’ll be using this type of hand pump!

qtrskills

I'll try to break it down into steps

1. Start with the car while its cold. (if you have been driving it your pan will be too hot and won't cool down and you won't be able to know when to drain in the last step)
2. Lift it, turn the engine off, drain fluid through the drain plug. Close drain plug
3. Fill through the fill port about 3 liters, close the fill port
4.Turn engine on while car STILL on the lift. (No need to drive it)
5. After 3 mins, turn the engine off. drain through the drain port. close drain port.

6. repeat step 3 to 5 (fill again with 3 liters, turn the engine on. wait 3 mins. engine off. drain)

7. Finally 3rd fill; fill 3 liters. turn the engine on keep filling till fluid comes out of the fill port. close fill port. go through all gears while waiting 5 secs in each gear. Shift to P. keep engine running. check the oil pan temp. when it reaches 95F. reopen the FILL port NOT the drain. fluid will pour out. when the fluid stops pouring and starts dripping close the fill port you are done.

That's why it's important to start with a cold car if you just drove to the mechanic your pan and trans will be hot even if the fresh fluid in it is not and you won't be able to do the last step.

Summary: Drain old fluid. fill and drain twice. you fill 3rd time. adjust the fluid level through the fill port at the right temperature. while the engine is running.

If you have questions let me know

AstatenateZ

That all sounds good and like my plan. My only issue is I can’t do it at my house. So I’d have to drive it somewhere. So I guess I’ll just have to sit around and wait for it to cool off. I’ll use fans or something to cool it off faster maybe?

Also I wonder what the dealership does, whoever comes in for a fluid change would of driven the car to them? So it wouldn’t be “cool” either.

But anyways yes that sounds pretty spot on to my plan , I’ll just have to wait around at first for it to be cooled off.

qtrskills

I see. I didn't mention it but I had another attempt to adjust the fluid while the car was hot and I couldn't because the tranny and pan were already higher than the correct temp which caused me to drain too much.
Now, this is not a problem for the dealer because they use the Consult II, there is actually a trans fluid sensor that only the ECU can read and it's not accessible through OBD

AstatenateZ

Ok sounds good. I’m just gonna use common sense (drain and measure, whatever comes out, I’ll put back in, maybe a tiny bit more to be safe) the first drain.

Second time. I’ll let it cool to proper temp, drain, then between 95-113 (roughly 104) I’ll add until fluid starts to drip out of transmission filler hole and then I’ll replace filler plug.