Doing the auto tranny flush......

Here's some good repair guides for your Tercel :) Look here for help first!
Post Reply
takza
Highest Ranking Member
Posts: 4414
Joined: Fri Apr 02, 2004 4:28 am
Location: Tibetan plateau

Doing the auto tranny flush......

Post by takza »

My experience (which is limited) is that when you change or flush an auto, you remove the buildup of clutch grit and metal particles (which are wearing your trans out), but you also put in new ATF which starts to pull the varnish and gum out off of the interior surfaces, valves, etc...and with the grit gone, you can have more slipping.

Best bet is to totally flush the trans thru the hoses at the rad...this way you can remove almost all the ATF from it and replace it with new...instead of about 1/2 of it thru the pan.

You would probably want to start with regular ATF and do a full flush 2-3 times lasting about 1000 miles of drivng each....in order to clean out most old sludge, grit, and varnish......and then put in Mobil 1 synth ATF.

Mobil 1 synth usually helps a trans to have crisp shifts, if it's not loaded down with crud.

The vacuum modulator valve also controls shifting in a major way and my limited experience says it would be best to use a used OEM vac modulator rather than a new aftermarket one. New OEM is even better.

How to do it: Check that the trans is at a FULL level first.

If you've removed or drained the pan, you've probably removed about 1/2 the ATF already & cleaned the pan & replaced the screen or filter.

With the front of the car up on ramps....find the hose at the radiator that comes from the trans (one that flows to the radiator), put the radiator end in a bucket...& with a hot trans...run the car at IDLE in PARK till the flow almost stops...then shut it off.

Add the same amount as you took out. Do this until you see clean new ATF coming out. If you have a clear container you can compare old & new ATF.

Put the hoses back on securely and check your ATF level. Drive for 1K miles.

* Need to be very careful when removing the old hose from the radiator...or you might end up replacing the rad. You also might want to replace the old hoses if they are hardened...but use ONLY the right hose type though. With new clamps.

Later, if you do the flush a couple of times without removing the pan...you will need to exchange all of it.

If the pan gasket did not leak, and it comes off with the gasket intact...just bolt it back on to specs...do not overtighten the bolts.

This flushing method is easier on the trans than the commercial methods, since it uses the regular working of the trans to do it. Keep things very clean...no lint from a rag even.

I also use Lubegard trans additive which can help with sticking valves and governors that synth ATF might not help...you need to buy the right kind for a Toyota though.

http://www.lubegard.com/automotive/index_trans.html


Also sell a flushing additive:

http://www.lubegard.com/automotive/trans_flush.html


I do a total flush about every 15K miles with Mobil synth ATF after cleaning the pan. And add more Lubegard. If this seems too expensive...maybe you let it go for 30K...but consider the cost of a rebuild?

Another method is to drain the trans pan at each motor oil change and refill, replacing about 1/2 of it. This would be done after the flushing process was done.

For a trans with a lot of problems......Valvoline MAXLife ATF might be the best...it is thicker and made for high mileage auto trans. Supposed to cure rough shifting, slippage, and shuddering. Flush first? Add Lubegard.

(note...I eventually tried this with the vehicle in question and it turns out that the MaxLife has a higher viscosity all right...and even with the Lubegard...the old shifting issue came back...stay with Mobil 1 synth?)

Some trans have bands/clutches that can be adjusted, but if it works reasonably OK...I'd say, just flush it and don't mess.

* no guarantees....this process may or may not work as expected....all transmissions are different....so are the people working on them....
Last edited by takza on Wed Jun 30, 2010 5:17 am, edited 1 time in total.
Give a boy a gun-give a biatch a cell phone-and pretty soon you almost got yourself a police state.

Orwell said: War is peace! Freedom is slavery. Ignorance is strength...

Image
sacwac
Top Notch Member
Posts: 152
Joined: Fri Apr 02, 2004 1:35 pm

Post by sacwac »

"The vacuum modulator valve also controls shifting in a major way........"

Where is this valve located? My transmission has problems staying in 3rd
(3sp auto). Proper fluid level, correct adjustment on the throttle linkage..

I will probably start a new post about it's specific problems, and the tests
I've done with it.

I'm curious to know if there was something I overlooked. I did notice a vacuum
line which comes out of the torque converter case, and goes nowhere.

-86 Tercel Wagon 4wd, 3AC, A55F
takza
Highest Ranking Member
Posts: 4414
Joined: Fri Apr 02, 2004 4:28 am
Location: Tibetan plateau

Post by takza »

sacwac wrote:"The vacuum modulator valve also controls shifting in a major way........"

Where is this valve located? My transmission has problems staying in 3rd
(3sp auto). Proper fluid level, correct adjustment on the throttle linkage..

I will probably start a new post about it's specific problems, and the tests
I've done with it.

I'm curious to know if there was something I overlooked. I did notice a vacuum
line which comes out of the torque converter case, and goes nowhere.

-86 Tercel Wagon 4wd, 3AC, A55F
The above info is generic in nature...in other words, I thought most autos had vac modulators...according to my Bentley manual - '80 thru '84...the Tercel doesn't.

Can say that the Bentley manual has a whole detailed chapter on the auto trans...not sure if they published one for '86 though...found mine on the net.

It has a trouble shooting section, but no mention of "not staying in 3rd". The one closest, "shifting back and forth from 2nd to 3rd", mentions "line pressure" or "governor pressure" being off or the valve body dirty or malfunctioning.

I have 1 repair method...FLUSH IT! Other than checking wiring and connections and the vac modulator.

My guess is that flushing a trans allows them function OK for longer despite some marginal pressures, etc.

If you don't have synth ATF in it or it hasn't been flushed, I'd try that. Also try the Lubegard...costs all of $10. Could be a valve in the valve body or the governor sticking.

My Nissan auto that had dark red somewhat burned ATF in it has shaped up and has handled over 50K of hard driving...so far.
Give a boy a gun-give a biatch a cell phone-and pretty soon you almost got yourself a police state.

Orwell said: War is peace! Freedom is slavery. Ignorance is strength...

Image
sacwac
Top Notch Member
Posts: 152
Joined: Fri Apr 02, 2004 1:35 pm

Post by sacwac »

thanks takza!

I will try flushing it... some time soon.

I will also post a much more detailed description of my tranny problems soon.
Post Reply