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Discussion Starter #1
My e46 is down while I take care of all the items under the intake: Under the Intake - What to Refresh?

It is relatively level, with the front wheels up on ramps (sloped driveway). I was looking at securing the bottom starter bolt from underneath and saw how easy it would be to change the tranny fluid right now.

I know all the threads talk about filling the trans when warm and filling until ATF starts to run out.

If you try to fill cold, do you end up with the incorrect level when filling?

Thanks all!
 

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'03 325iT Mystic Blau
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My e46 is down while I take care of all the items under the intake: Under the Intake - What to Refresh?

It is relatively level, with the front wheels up on ramps (sloped driveway). I was looking at securing the bottom starter bolt from underneath and saw how easy it would be to change the tranny fluid right now.

I know all the threads talk about filling the trans when warm and filling until ATF starts to run out.

If you try to fill cold, do you end up with the incorrect level when filling?

Thanks all!
Yes.
 

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2004 330Ci 85k miles
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11,173 Posts
the trans pan is smooth on the bottom. Does that mean I have the GM 5L40-E?
Yes. Please read post #1 of our Official ATF thread for the details, pics, etc.
 

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Discussion Starter #7
Yes. Please read post #1 of our Official ATF thread for the details, pics, etc.
Thanks. My pan looks a little different than the smooth pan you have pictured. I think I have a picture...
 

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Thanks. My pan looks a little different than the smooth pan you have pictured. I think I have a picture...
Yeah, the pictured pan isn’t exactly the right one. You have either ZF with the cross-hatch pattern or GM with the smooth pan.
I updated my thread with a more accurate photo.
 

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2004 325i automagic
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Tthe ATF fluid should be warm not hot between 30C to 50C or about 85F to 120F. Body temp is an ok proxy but using an IR thermometer measuring on back of the pan is pretty accurate actually (I have compared it with the trans temp reading using a scantool and the numbers are essentially the same).

If it gets too hot it will be underfilled due to fluid expansion, too cold will overfill. If it gets too hot b/c you take too long fiddling with the hand pump, changing bottles and so forth, make sure to let it cool down and then recheck to the level when warm. BTDT and it was definitely underfilled and not functioning correctly. Car needs to be level for a proper fill.
 

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I always verify the vehicle is level before touching the fluid and check this with a basic level tool in three areas:

-Center of the roof.
-Interior center.
-Transmission pan itself.

As for the fill, it is done in two stages. The first is always a cold fill and the final fill, as others have mentioned, needs to be warm.
 

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Discussion Starter #13 (Edited)
I always verify the vehicle is level before touching the fluid and check this with a basic level tool in three areas:

-Center of the roof.
-Interior center.
-Transmission pan itself.

As for the fill, it is done in two stages. The first is always a cold fill and the final fill, as others have mentioned, needs to be warm.
Thank you! Does the engine cover in between the intake and valve cover represent a good level measurement?
Trans pan makes sense to check!
 

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Thank you! Does the engine cover in between the intake and valve cover represent a good level measurement?
Trans pan makes sense to check?
No problem! It's not centrally-located but it is a flat surface.

I'd think the pan itself is the most accurate point. Any modestly-priced magnetic level tool will verify things for you.

 

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Discussion Starter #15
Just to be obsessive about this, I can drain the tranny when cold, and fill it to the fill hole, with the understanding that the fluid level will be low.

Then I can start the car, put her in gear (R or D) and add more fluid until the pan is warm, but not burning hot. Replace fill plug and all is well - assuming the car is level.

Yes? No issues starting off with a low fill level after draining the trans cold?

Thanks...
 

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You should drain it cold because in order to get the proper fill level the atf temp needs to be between 85 F to 120 F ( 30C to 50C) when you are finishing.

However, the need to run the engine is not entirely due to the atf temperature strictly speaking, because when the engine runs the pump draws fluid out of the pan and up into the transmission itself and let's you put in almost another quart in before the atf starts dribbling out the fill hole (again).

However, if during the final second fill step with the engine running (or if you are just checking the level) the atf is too hot (above 120F/50C) then you will underfill because the too hot fluid expanded too much. This I think is the main reason to start the process cold, so you have time to run through the gears a couple times (to circulate fluid through valvebody) and time to pump enough fluid in on the second step fill without the atf temp getting too hot.

If atf gets too hot (because you had to fiddle with the hand pump) then you need to plug it back up and wait until it cools down again. Btdt.
 

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Yes? No issues starting off with a low fill level after draining the trans cold?

Thanks...
Yes, no issues here. That first cold fill with engine off gets enough fluid in to circulate through the system, but since you are not driving it or allowing the wheels to spin (keep foot on the brake as you cycle through the gears) there are no issues.

Just make sure the atf doesn't get too hot during the second step fill with the engine running. Use INPA to monitor temp if you have it, or if not use a cheap infrared thermometer on the back of the pan.
 

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Fill cold to warm. I prefer the lower end of the scale
Gets more fluid in.
Absolutely no need to run it through the gears. We stopped doing that a decade ago. No issues whatsoever.
 

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Discussion Starter #19
Good news is my pan is pretty close to level on the ramps!
Just need to get the fill plug loose...
 

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Should be a T-45 torx, but no room for a both a socket & ratchet in there. If the torx bit has flats (and fits) you can use a wrench on the flats to turn it and a second wrench over the first one to get leverage ... that sucker is on there tight.
 
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