Flushing automatic transmission

[Barwich]

Hi all. I recently purchased a 03 Mitsubishi Montero, My plan was to swap all the fluids before winter. I've done front/rear diffs, transfer case, and engine. My original plan with the transmission was to just drop the pan and replace filter/fluid. On this particular transmission there is a drain plug. After seeing the condition of the fluid come out I've decided to do a full drain and replace with Amsoil SS ATF.

Is the following procedure correct?

1. Refill the same amount of ATF drained from pan.
2. Pull return line at cooler.
3. Shift to neutral, turn on engine for 30 seconds to 1 minute. Drain return line into container.
4. Drain transmission pan via plug.
5. Add same amount of ATF that was previously drained.
6. Start engine in neutral. Shift through all gears.
7. Wait for fresh ATF to come out of return line.
8. Shut off engine. Put everything back. Refill remaining ATF.
9. Start engine, inspect fluid level after engine is warmed up.

 

[Merkava_4]

Pull the pan and wipe out all that accumulated gray clutch disc material from the bottom of the pan. Install new gasket and filter. Done. Some of the simple things in life should be kept simple.

 

[demarpaint]

I just did mine on Sunday. I won't go through the process I did, since you're already on the right track. My suggestion would be a pan drop, clean the pan and magnet, and replace the filter. Then do your line off exchange.

I would do the line off exchange with a helper, and not based on your 30 second to 1 minute run time to pump out the system. The last thing you want to do is run the pump dry. Get a clear hose and a clear container to drain the fluid into, as soon as you see bubbles or it spit ATF turn it off! Replace the fluid and repeat until clean fluid is being pumped out. Put it back together re-fill with the proper amount and check, then re-check to see you have the proper level. Look for leaks, job done.

 

[MaximaGuy]

Replace the magnets with new ones would be an added bonus

 

[doitmyself]

I agree on first dropping the pan, cleaning it, and filter replacement. Is step 4 required on the return line process?

 

[demarpaint]

Originally Posted By: doitmyself
I agree on first dropping the pan, cleaning it, and filter replacement. Is step 4 required on the return line process?


Kind of a moot point?

 

[mclasser]

Is that the gen Montero that had tranny overheating problems due to small pan size? Can't remember if it was this or the Montero Sport.

 

[DoubleWasp]

Originally Posted By: Barwich
Hi all. I recently purchased a 03 Mitsubishi Montero, My plan was to swap all the fluids before winter. I've done front/rear diffs, transfer case, and engine. My original plan with the transmission was to just drop the pan and replace filter/fluid. On this particular transmission there is a drain plug. After seeing the condition of the fluid come out I've decided to do a full drain and replace with Amsoil SS ATF.

Is the following procedure correct?

1. Refill the same amount of ATF drained from pan.
2. Pull return line at cooler.
3. Shift to neutral, turn on engine until air bubbles start to appear.
4. Drain transmission pan via plug.
5. Add same amount of ATF that was evacuated through the cooler line.
6. Start engine in neutral. Shift through all gears.
7. Repeat 5 and 6 until fresh ATF to come out of return line.
8. Shut off engine. Put everything back. Refill remaining ATF.
9. Start engine, inspect fluid level after engine is warmed up.


Fixed.

Once you evacuate the pan through the cooler line, it will not have old ATF in it again. No need to drain the pan again. Only fresh ATF will come out.

Just keep going with the cooler line flushes and fills of the same amount that came out until you get fresh ATF coming out of cooler line.

 

[buck91]

Like Doublewasp said above. I've done this on a couple vehicles and it works pretty great (unless you have a thermostatic cooler line like my F150

). Make sure you keep an eye on your drain hose and kill the motor as soon as you see any bubbles. Also, you can make it easier on yourself if you use a graduated container to measure your ATF as it comes out of the line, this way you can just add that exact amount back in during the process. Keep repeating that cycle until you have replaced a little more than the entire atf capacity (like 1-2qts extra is all I've ever done).

 

[GenesisGuy70]

Originally Posted By: buck91
Like Doublewasp said above. I've done this on a couple vehicles and it works pretty great (unless you have a thermostatic cooler line like my F150

). Make sure you keep an eye on your drain hose and kill the motor as soon as you see any bubbles. Also, you can make it easier on yourself if you use a graduated container to measure your ATF as it comes out of the line, this way you can just add that exact amount back in during the process. Keep repeating that cycle until you have replaced a little more than the entire atf capacity (like 1-2qts extra is all I've ever done).


Woah woah woah? WHAT? You're joking right? 1-2 QAURTS EXTRA?

That is the absolute dumbest thing I think I have ever read on this entire forum.

You fill to factory spec and not a drop more.

 

[buck91]

Throt... You don't overfill the trans, you just want to make sure you use a little extra fluid during the procedure to make sure its all fresh.

For example, say your trans is spec'd to 10qts. You would want to keep flushing until you have purged 10-12qts.

 

[GMBoy]

Originally Posted By: MaximaGuy
Replace the magnets with new ones would be an added bonus


Why? They don't wear out or go bad. You clean them and reinstall.

 

[GenesisGuy70]

Originally Posted By: buck91
Throt... You don't overfill the trans, you just want to make sure you use a little extra fluid during the procedure to make sure its all fresh.

For example, say your trans is spec'd to 10qts. You would want to keep flushing until you have purged 10-12qts.


Ahhhh I get it. That makes WAY more sense to me. It didn't sound like that in your original post so my bad for the reaction lol.

 

[buck91]

No worries, I guess I was a little imprecise initially.