JOESPIFFY

going to flush my tranny. easyest way to disconnect line is from upper cooler connection? or is their an easier fitting to use? 1986, 700r4 trans.

Cjunkie

Just drop the pan and change the filter. Get 6 qts of Dexron III, your going to use 5 1/2.

ex-x-fire

Do this ^^^ and you could later extract the tranny fluid after running it for a while. I'd say you would change 90% of it. There's some pretty reasonable extractors out there or you could make one.

JOESPIFFY

I already changed the filter. fluid was very dirty, need a total flush to try to save the tranny.

aklim

Have you tried a place that does oil changes? See if they have a flush machine? I wouldn't think that it can save the tranny if it is toasting but it can stop it from going worse as fast as if you did nothing.

JOESPIFFY

what I really wanted to know if anyone has done it before,and is the upper line the right place to disconect. or, is there an easier place to discharge the fluid? I already changed the filter.

ex-x-fire

In my experience with GM tranys, the lower cooler line is the inlet for the cooler. I'd make up a piece of line with a flare to hook up to the upper cooler connection. Get some rubber or nylon hose and run that to a bucket.
Be ready to dump a gallon of atf in when you start it.

Cjunkie

Then drop the pan one more time. If dropping the pan twice doesn’t ‘save’ the tranny you have bigger issues beyond transmission fluid.
Earlier this year on my 86 a 1 time pan drop and filter change was all that was needed. I have been all over the US with it this year and the trans shifts beautiful.

WVZR-1

^^^^

I believe that if you feel you've potential issues the second dump, filter and fill will do.

A DIY flush for a novice has maybe a few challenges such as twisted cooler lines and destroyed flare nuts and on and on, could prove very costly. Many might not do the 2nd filter

You've never mentioned the miles, haven't mentioned if the car has been driven since the 1st filter change so maybe it's important to mention both, miles on car and driven since filter/fluid.

BlowerWorks

Agree 100% !!! Use Amsoil SuperShift then maybe 5000 miles or less do again. You will not be sorry !!! greg

Cjunkie

I used Supertech off the Wal-Mart shelf.

Purple92

I have never done a auto trans fluid flush on a Vette - but I have used a very similar process to what you describe on my K3500 with a 4L80E tranny.

Dumped the pan and filled with new fluid. Disconnected one line at the cooler - and started the engine. Killed the engine when I saw the first sign of bubbles in the tranny fluid - refilled pan - repeated process three times - at that point the fluid coming out was pretty darn close to new looking.

One post I saw felt that the fluid returning to the tranny from the cooler did some lubricating, and that it would have been better to have a person continually adding fluid to the car while the cooler line was disconnected. If I had a third person available I would have done that ...

JOESPIFFY

I will be adding fluid as i go. you have to be prepared with everything before you start the engine! they have video on u-tube on how it works.look at trans flush. it can be done in 25 min. if know what to do. some of those videos are not that good!

aklim

And exactly why do you want to do this instead of farming out this messy crap?

Purple92

I obviously can't speak for the OP - but in my case - the job wasn't too horrible - the 4L80E pan has a drain plug - so I was able to avoid getting old trans fluid all over myself - and while the pull the line off the cooler part wasn't a ton of fun - it was a lot less of a PITA than doing even one bank of spark plugs on an LT1 - C4.

BUT - my main reason was that while there are some "local" Independent shops that I use and that I have had very good luck with - most of them don't have the flush machines, and the majority of places that have the machines - I just don't trust !!!

Del96lt1

Years ago, I attended a seminar held by Gordon Killebrew on maintenance and repair of the C4.
One of the tips he gave us was flushing the Trans.
You'll need 12 quarts of new fluid.
Disconnect the upper trans cooler line on the radiator. (Upper passenger side of the radiator) Connect a tube to the line, into a large drain pan.
( I use 3/8" ID clear tubing from Lowes)
Start the car, run it until it spits, shut car off.
Put 4 qts fluid in Trans.
Start the car, run it until it spits, shut car off.
Put 4 qts fluid in Trans.
Start the car, run it until it spits, shut car off.
Reconnect cooler line to radiator.
Put 3 qts fluid in trans.
Start car, at idle, without moving, shift into all gears, then into park.
Top off with last quart of fluid.

You've just changed every bit of fluid in your trans.
Easy.

Regards,
John

mako41

Yes I agree that's what I did to flush all the fluid out of my 700R4, including the fluid in the converter!

aklim

OP is at the point of "it is very dirty and need to flush to save the trans". Put it this way, if they wreck it, they are doing him a favor. If not, life is good.

86project

Hello DeL96, just to clairafy, connect a tube to a large drain pan, you then start the car and drain 12 quarts of fluid , I didn't see anything about the drainage procedure, or was I to assume that? That also includes the torque converter? Thanks in advance.