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DIY 5EAT ATF Flush


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Two Notes:

1) This is very easy with proper preparation, will save you a lot of money, and will give extra years to your 5EAT.

2) I don't have pictures of it being done on an LGT, so I'm blatantly using other peoples' photos and videos to illustrate the point.

 

I do this to all my cars, same procedure. All my cars shift perfectly.

 

Things you need:

1) ~12 quarts ATF (OEM Subaru HP+; Amsoil ATF; Mobil 1 Full Synthetic ATF)

2) Funnel that fits into your transmission's dipstick tube / fill tube.

3) Graduated bucket (bucket to catch fluid, with markings to tell you how many gallons are in it.

4) Plyers, basic other hand tools.

5) Optional part 1 of 2: 3/8" doubled sided hose barb, auto parts store or hardware store. You might not need this, but it costs $2.

6) Optional part 2 of 2: 10' of 3/8" I.D. hose, cheap, auto parts store or hardware store.

5) The cognizance that cars are cramped, dirty, sensitive machines that you should not mess with if you do not know what you are doing.

 

Summary of Process:

1) Unplug ATF cooler line return hose from any return pipe section. (If you don't know whether a line is output or return, unplug a line and run the engine for a couple seconds. The line that spits out fluid is the line you want.

2) Optional: Connect an extension hose (use barb adapter if attaching hose to hose.

3) Put graduated bucket next to open driver door, put extension length of hose in bucket. Maybe tape it so it doesn't fall out.

4) Turn engine on. Turn engine off when A) bucket fills with 3-4 quarts of ATF, or 2) trans starts making an odd noise.

5) Use funnel, put matching amount of fresh ATF into trans.

6) Repeat 4 and 5, this time quickly switching into Reverse, Neutral, Drive (but don't let the car move).

7) Repeat 4, 5, 6 until you run out of fresh ATF, or ATF starts coming out clean.

8) After car is put back together, drive for 10 minutes around town (with funnel and extra fluid in car). Then with car idling, check fluid level, get it between the two HOT marks.

 

Note: People like to complicate the heck out of this. Keep it as simple as possible, as few steps as possible. Example: If you have a friend to start and stop the engine at your command, then you may not need to rig up an extension hose if you can get your fluid catch bucket under the car. You also don't need a graduated bucket if you have a general sense for how much fluid is going in your bucket. Absolutely no need to pull the pan plug. Waste of time.

 

 

 

Watch this video:

Skip to 2:57 for instructions. Everything else is a waste of time.

 

 

This great walkthrough shows the several trans ATF cooler hoses/pipes you can unplug on page 3,4,5, and it shows a sample double sided 3/8" hose barb on page 1. http://subaru.rockhopjohn.com/Transcool.pdf

 

 

Example on a Toyota Truck (skip to Step 4 and 5): http://www.toyotanation.com/forum/61-2nd-generation-2005/326809-diy-full-automatic-transmission-flush.html

 

 

On the LGT: The cooler pipes run along the driver side framerail up to the front of the car. You can pull a line under the car if you remove the skid plate. There are lots of pictures somewhere on this forum of this area of ATF cooler lines. If you have links, post them please :)

Not all ATF cooler line routing is the same, from Legacy USD to Legacy JDM to Outback to Tribeca, 3.0r, there are variations. So pictures may or may not be indicative of what you will find on your vehicle. For example, the Tribeca ATF flows through the radiator in the opposite direction as the OBXT / 3.0R / LGT. So take the extra minute to check for yourself, assume nothing.

 

Basically, if you can't find the cooler lines, or can't get to them, that is a good indication that you might want to seek the guidance of a friend, or just simply not do this yourself. It's the kind of thing that is easy to do, and easy to screw up such that it ruins your day. As some CarTalk callers have admitted, even a simple oil change can end up taking days and require a tow truck if you unintentionally make a mistake.

 

Ask questions if you have any.

 

A word of caution...

 

A few days ago, someone on these boards reminded me of a risk of doing a complete flush all at once: If the fluid is VERY old, then there could be a lot of gunk buildup in the transmission.

ATF contains detergents, but this detergent cleaning ability fades over time. Putting all new ATF in a gunky transmission could dislodge all that gunk too quickly, causing the clogging of certain parts of the trans.

If you want to be careful to avoid this risk, then BEFORE you do the full flush:

Remove one old quart of ATF, and replace with one new quart, then drive around for 100 miles. Then repeat once or twice more, or until you feel confident that you are not going to unleash a wave of gunk deposits. This is being seriously careful; use your judgement.

 

I would not worry about this problem at 30k or even at 60k miles, but at over 100k, consider it.

Edited by ClimberD@HexMods
[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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Just did this in a very similar fashion with about 8.5 qts. Worked great.

 

8.5 quarts is all it took... nice... did you go through the gears few seconds each?

 

I did empty the pan on the premise that whatever was being pumped from there would then be clean fluid, but whatever.

 

Yup same end result either way, pan gets emptied of dirty fluid, filled with clean, a couple times. My method simply cuts down processes from 2 (pan and line) to 1 (line only). FWIW I've done it both ways, and on one stupid car could only do the pan method because the lines were either crimped or used special release fitting that I felt might crack. That took a lot longer, more wasteful, but in the end got the fluid all fresh.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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Nah, I just had about 9.5 qts on hand so I only put in 8.5 so I'd have a qt left for filling up as needed. I didn't think to go through the gears, but given that I was only doing a 2/3 replacement I don't think it really would've mattered. I did a drain / fill about 10k miles ago, so I'm pretty confident that my atf should be in good shape for a while now.

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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Don't know if these are helpful for folks (sometimes the angles are hard) but I took a couple of pics when I did mine. The first shows two of the hard lines for the ATF. Looking at that photo, the line to the right (rear of the car) is the return line that goes back to the case. The line to the left (front of the the car) is the line that is post filter / pre radiator after the ATF leaves the case.

 

In the second pic, you can see that I disconnected the rear hose right before the fluid goes back to the transmission. I had a wrench attached to weight it down, but I ended up just stuffing it into an empty rotella container and pumped out a quart at a time. The oil container has markings on it so I could tell how much I was pumping out and just continued to add as needed.

DSC_0092.thumb.jpg.30442f2f518eb08f4deea79effa43e07.jpg

DSC_0093.thumb.jpg.ffc95fecff8ade67df86ee1381451162.jpg

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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Is it recommended to replace the tranny filter? I'm about to perform a drain/fill twice on my subaru. I bought 12 quarts of Royal Purple tranny fluid and plan to do it this weekend.

 

No. No need to replace the filter unless it is physically damaged or leaking.

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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  • 2 weeks later...

Worked like a charm! 2005 Outback XT. Used the suggestions from BarManBean, unhooked the rear line coming from the radiator cooler (I had just taken this off two weeks ago for the timing belt - It was quite tough to get off then. Grabbed it gently with pliers and twisted until the seal was broken. Then pulled by hand). It comes out fairly slowly. 5 seconds was well less than a quart. I put in 10 quarts, but it didn't come out clean. I only had 11, and I wanted one for topping off, so I stopped. The fluid on the stick was very clean. I can only hope I was close. I think capacity is 12. I marked an old washer fluid container and stuffed the end of the hose direct from the car in there. I would pump out 2 qts, fill two new quarts in with a funnel and a 1-2 ft flexible hose (came as a unit from Oreilly - the cheapish plastic gray one with a clearish ribbed hose) leaving the funnel in place the whole time.

 

After 7 years and 105k, the old fluid looked a lot like oil, and nothing like ATF. I've noticed hard shifting lately. Hopefully this will help. Otherwise I'll ask the dealer to relearn the shifting. Apparently something they do on the lift with the Subaru Select Monitor III.

 

Thanks for the tips! Probably should have done it a lot sooner!

 

EDIT: after thinking about it, I realize I should have drained the pan. Since it holds 4 qts, when you empty the first two, you are then adding two new quarts to two old quarts. Probably better to drain, and start with 4 fresh in there.

Edited by tdelker
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I'm going to use this procedure soon on my wife's '05GT, but I'm going to drain the pan first. I assume it'll have a magnet on the drain plug and I want to clean it off and also make sure it's not loaded up with metal shavings. Is there a copper washer on the tranny plug that will need to be replaced?
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I agree with draining the pan first--also ensures that you are pumping fresh fluid through the system from the get-go. There is a crush washer there, it's not copper but it is one-time-use and should be replaced.

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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PS: This appears to have solved a hard shift between 2nd and 3rd in my 5EAT. Much smoother now. I really should have done this is 60k rather than 105k!

 

Good lord... 105k on the same ATF? Dang. Glad you did it. Will give the trans a new lease on life.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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A word of caution...

 

A few days ago, someone on these boards reminded me of a risk of doing a complete flush all at once: If the fluid is VERY old, then there could be a lot of gunk buildup in the transmission.

ATF contains detergents, but this detergent cleaning ability fades over time. Putting all new ATF in a gunky transmission could dislodge all that gunk too quickly, causing the clogging of certain parts of the trans.

If you want to be careful to avoid this risk, then BEFORE you do the full flush:

Remove one old quart of ATF, and replace with one new quart, then drive around for 100 miles. Then repeat once or twice more, or until you feel confident that you are not going to unleash a wave of gunk deposits. This is being seriously careful; use your judgement.

 

I would not worry about this problem at 30k or even at 60k miles, but at over 100k, consider it.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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So far so good. Much different shifting, as I said - No more 2nd to 3rd shift shock. I'll report back if something bad happens. Also finally change the front and rear differential fluid.

 

I'll make a note to do the ATF again in 60k.

 

Tom

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To answer the other part of your question. There is a big magnet on the inside of the pan, but not on the drain plug. To clean off the magnet, your would need to remove the transmission pan, instructions for removing and re-installing are in the F1 Valve Body sale thread, 1st post.

 

If you wanted to buy a magnetic drain plug, it's M18x1.5, with as little bolt head sticking out as possible (stock is recessed with a hex allen socket).

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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  • 2 weeks later...
Picked up the Subaru ATF-HP at Hueberger yesterday. Used a 20% off coupon and got it for $5.94 a quart.:) I forgot to get the stupid crush washer for the tranny drain pan though.:mad: I'm thinking of just reusing it as I do with most crush washers. I never get leaks from reusing my oil drain plug crush washer. One question though, is it better to do this job when the car is cool or hot or does it even matter?
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Picked up the Subaru ATF-HP at Hueberger yesterday. Used a 20% off coupon and got it for $5.94 a quart.:) I forgot to get the stupid crush washer for the tranny drain pan though.:mad: I'm thinking of just reusing it as I do with most crush washers. I never get leaks from reusing my oil drain plug crush washer. One question though, is it better to do this job when the car is cool or hot or does it even matter?

 

A) Crush Washer - You can re-use it as long as it is cleaned and will / does still form a good seal when re-used.

 

B) Temperature - Does not matter, unless it's hot enough to burn yourself (should go without saying, but I've heard of people forgetting the fact these things can sit at 200*F easy.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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Did the job today. Went through 11.5 quarts of fluid and now it's nice and red instead of brown. A messy job to be sure, especially as my funnel wouldn't fit all the way inside the stupidly small trans. dipstick/filler tube. I couldn't even fit my hose style funnel in it that fit easily inside the front diff dipstick/filler tube. Regardless though, even at only 46k miles the fluid looked to be in need of changing. I can not even believe Subaru says this service is optional!:eek: I don't know if I'll do this again in another 30k miles or another 50k miles. I think I'll go ahead and change out the filter next time too.
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