Method of changing ATF

[benex]

I have read several posts on changing ATF with in this site. It is a bit confusing.

One said "The ATF will take a couple of drains. Only 3 quarts come out if you just pull the plug. "

(hmmmmm....... a couple of drains? )

Another posts mentions that a dealer used 5 quarts when changing his ATF.

My Helms manual says that the tranny capacities are about 14 quarts.

I know I am ignorant, but shouldn't all of the ATF be changed out?

Can someone comment on this?

[blue2kzr2]

The torque converter holds quite a bit of ATF. There isn't an easy way to drain it unless you pull the transmission. Some people will suggest doing several quick successive changes, maybe every 1000 miles if you REALLY want to get it all out. However, many people have been decent service from their vehicles just changing out what would drain when the pan is dropped.

[JayMan]

I will get almost 6 quarts out when I drain the pan, drop it, and change the filter sock. The rest stays behind in the torque converter.

 

Of course, you can go to a shop that offers a transmission "flush" gadget, like a Motorvac TransTech: it plumbs into the quick-connect trans cooler connection and exchanges almost 100% of the trans fluid.

 

There are pro's and con's to getting a flush, and previous threads have covered this in detail. The biggest worry is that the shop won't service the trans first, so the new fluid will knock loose the crud and plug the filter and valve body.

 

Not sure why they don't put drain plugs on torque converters. My 1984 Ford F-150 with C6 auto has a torque converter drain plug, which is about the only good thing about that Ford. That's the only reason I bought it new.

 

The drain plug is very small, if I recall you need a 9/16 socket to get it off. It takes forever to drain too, but then you've drained out +95% of the fluid.

 

With that old C6, a trans service easily takes 16 quarts. I'd almost be better off buying Mobil 1 ATF by the pail.

[TonyD]

I am interested in doing this myself. I am a novice and definately want to do this right. I want to change to synthetic atf also. Question: On my 2000 gmc sierra 1500 should I just drop the pan and put synthetic in? Is the filter easy to replace and what else should I do? What filter kit should I buy? Do i need a new gasket for the pan? Thanks..This forum has been very helpful to me.. I changed my fuel filter and switched to Mobil 1 because of all the info..Thanks again..

[SilveradoWV]

You are wasting your time and money if you just drop the pan and refill with synthetic. The amount of synthetic that you would add in a "pan drop" would not even make your tranny fluid a 50/50 syn blend. If you want synthetic you would really need to flush with synthetic!

[Ben]

Posted before and here it again.

 

Do both pan drop and filter change along with the 12 quart on 4L60E and 16 quart on a 4L80E transfusion.

 

Need:

 

5 gallon catch bucket

length of cheap clear hose, think 5/16" ID will do.

12-16 quarts of ATF of choice

ATF funnel (long, thin funnel)

tranny filter

tranny gasket

basic tools

tons of rags

 

Disconnect tranny line (pressure line from tranny to radiator)

 

Connect clear hose to the tranny line.

 

Put clear hose into catch bucket.

 

Mark high water marke on catch bucket for 4 quarts.

 

Start engine and allow it to pump out 4 quarts, then shut off. If you get the wrong line, you'll know pretty fast, as it will gush out the "other"...

 

Do the tranny pan drop and replace the filter and gasket. Button it up.

 

Add 4 quarts of ATF.

 

Start engine and allow it to pump out another 4 quarts. Stop engine.

 

Add 4 quarts of ATF.

 

Repeat till you've added enough to flush the tranny.

 

Hook back up the tranny line to the radiator.

 

Done. Complete tranny flush and filter change. Can do this in less than an hour.

 

DO NOT allow the tranny pan to go empty or allow it to draw in air. It will potentially RUIN the tranny.