Question about doing trans fluid change via trans cooler lines.

[Gwokable]

How should I go about doing a transmission fluid change?

I know how to do a filter and gasket replacement. That's simple enough. But that only gets 4 quarts of 12 quarts of fluid, and I want to change out all 12 quarts, which means I need another method.


Now the other method I'v heard talked of on this board is as fallows. I'm wondering if anyone's done it and if so, how successful they were.

*Pull trans pan, install new filter and O-Ring, check swarf, reseal pan.

*Fill tranny up with fluid and cleaner.

*Run car in nuetral to recirulate fluiid as directions state.

*Pull trans cooler lines off of the radiator, get 5/8ths inch hoses and clamps. Install hoses onto trans cooler lines.

*Run bottom return line to the bucket filled with 16-20 quarts new fluid. Make sure to pump fluid into the hose before turning the car on to reduce air going into the trans.

*Run top output line to another bucket.

*Turn car on, watch buckets. When bucket with new tranny fluid gets nearly empty, switch the works off.

*Check fluid level. If necissary, insert hose into trans dipstick to extract some fluid. If necissary, add some fluid into the pan.

I don't know if that'll get nearly 100% of the fluid or not but, having talked to some mechanics, they say it'll work. However, being cautious and from a technical backround, I like to triplecheck a process before doing it.

[90Brougham350]

You are exactly correct in your thinking. This process is the best method of changing the fluid completely.

[Hammondsix]

i tried this only to find that one line pumps out the fluid and the other did nothing. The other line didnt suck!

[tipoil]

your right Hammondsix mine too didnt suck

what i do when i change trany fluin is

drop the pan and filter

put new filter in

put the pan on

disconect cooler hose that exit the rad(if ur not sure witch one, try one and see from what end it flows)

overfill the trany ( in my case i put close to 8 qts in last time i think...)untill it start comming out of the vent

have someone start the engine in park

add fluid after 4 or 5 qts come out

when the good stuff come out(bright red trany fluid) stop the engine

replug the cooler hose

start er up again to check the fluid lever

if close to ok

run to all the gear a few time and recheck

if too high unplug cooler again and flush it up some more

if to low and a few in

remember full line on the dipstick is when the trany fluid is realy warm to the touch

hope it helped a bit

[Hammondsix]

I'm planning to install one of those shiny aftermarket pans that has a drain-bolt and change with the engine oil every 7500 miles.

[90Brougham350]

Dear God! 7500 miles is too often. No need to change the fluid less than every 30 or 40,000 miles.

[Old Fleetwood]

Amen to the 30,000 mile change.
I'll take the work of Shane Cobb of Carolina Performance Transmissions, especially since I'm driving around with one of his Stage II 4L60E Units in my 95 FWB.
Sure, some say you can go a lifetime with no change, etc., but Shane says for best results go with GM's "Hard Service" recommendation of 30K miles change.
But 7,500 wouldn't hurt anything but the pocketbook!

[Hammondsix]

I disagree, the standard 30k mile fluid change calls for ALL of the fluid to be drained. When you drop the pan you only get 5qts or 1/3 of the fluid out of there. Thus the need to do it more often than 30k miles. Now if one unhookes the coller lines and get the additional fluid out of there, thats another deal.

[Old Fleetwood]

Okay - I think I see where you're coming from. You're getting that 30k change, 5 quarts at a time every 7.5k miles.
Right?

[Hammondsix]

precisely

[Gwokable]

Every 20k is best IMO.

[Old Fleetwood]

Do you mean a FULL FLUSH AND FILTER CHANGE EVERY 20,000 MILES?

[Hammondsix]

Numerous people on the board have said that flushing is a bad thing and makes the trannies blow up in million peices. I have done it twice with my other cars and they never did catch on fire, blow up or turn into lava. Maybe this subject would be suitable for the www.impalassforum.com since those guys eat trannies for breakfest.

[dustman]

What i am about to post is not speculation or hearsay but FACT.
The 30K Pan drop and filter change is the GM recommended service.
This is what should be done to all 4l60e equipped cars. Nowhere does hydramatic recommend flushing on the 4l60e in these cars. INfact when i was forced to flush transmissions at a dealer that i worked at that Upsold aftermarket BG flushes i saw some transmissions die in short order after a flush.

You must remember that a transmission isnt a engine. Super slippery ISNT what we want. We WANT some friction floating in the fluid. All the CRAP is in the filter. So unless your drag racing your 4l60e EVERY wekeend do a 30K serice Pan down and filter change.

If you drag race often once a year regardless of mileage.


Stick With GM Dex 3 and also do NOT do flushes only pan downs. If your told otherwise your told wrong.

[blackcadmatt]

I had the tranny in my '89 Brougham professionally flushed at a garage using a MotorVac tranny machine that I sold them. No mess no fuss, AND the torque converter gets cleaned too. The car runs and shifts like new! It was free for me as a demo but most shops charge less-than $100 for this service.

It's well worth it!