4l60e return line

[sydsider]

Im doing an oil change tomorrow.
Im planning on pumping it out through the return line to the radiator.
Can someone advise as to which of the two pipes is the return line to the radiator?

Thanks.

 

[Fu Manchu]

Bad idea. Just do it from the pan as intended.
If that’s messy, do it this time and install a trans pan that has a drain plug.

 

[sydsider]

It has the low viscosity fluid and its slipping so i want to get it out and replace with Dex3.
Im trying to get as much as i can out.

 

[Ginger Beer]

To fully flush the transmission you need to think about the torque converter that holds alot of the oil, which, if you only drain the pan, doesn't get that oil.

"Around 1/2 of your trans oil is in the converter.

A 4l60e needs about 5.5 litres on a pan only service, but, after a rebuild it takes about 10 litres, so 4.5 litres of old oil is left in the converter to mix with your new oil, so at best, it is a 50/50 mix of new and old oil when doing a pan only change.

There is a few ways to do it, some recommended, some not.

Recommended ways.

What I do. #paycashnow
1. Pay a trans joint to flush all the oil, they can connect up lines to the in and out lines to fully flush the trans, including the converter, typically they drain the pan and replace the filter, then refill the pan prior to connecting the lines to flush.

DYI way. Costly with the price of trans fluid

1. Drain pan, put in new filter, refill and run the car
2. Drain pan again and run the car
3. Drain the pan and refill

Whilst not truly "flushed" it does freshen up most of the oil in the whole transmission.

Not recommended way

Disclaimer, I'm not a transmission specialist, but, I know people who have done it this way without and "apparent" damage to the transmission

 

[sydsider]

Is there a way to drain the torque converter?
I think it holds a couple of litres.

 

[Immortality]

I do what you suggested. On a stock pan I'll drop the trans cooler line and pump out about 4 litres (I don't let it run till the pan runs out of fluid). Then I'll drop the transmission pan, change the filter and top it up with new fluid. Then start and idle the engine running the fluid from the trans cooler line again until it looks like clean fluid. You might have to stop and top up the trans when you do that. Normally I'll pump out about 4 litres and then stop to not risk running the the trans empty.

Fluid coming from the converter goes straight to the trans cooler.

Ideally you'd use the return line from the trans cooler but that will most likely be a solid steel line, I just drop one of the flex lines going to/from the cooler, direct it at a container and have a helper start/stop the car to check which end the fluid is coming out off and then change lines if required.

 

[sydsider]

I drained out about 6 litres last June when i gave it a service after buying it a year before.
Supposedly theres 7.9 litres in it, so the rest being about 1.9 litres was still in the torque converter, the two lines to the radiator and the radiator cooler.
Ill be changing the 1-2 accumulator piston and o ring with an alloy one.

The top line out of the tranny is the return line, so i suppose just follow it to the radiator and remove it.

 

[Fu Manchu]

That would just make me nervous as.

 

[sydsider]

That would just make me nervous as.

Ive done it on a TJ Magna a couple of years ago.
And i was nervous, but it worked.
I read up a fair bit before doing it lol.

 

[sydsider]

I have these about pumping the fluid out.

https://forums.justcommodores.com.au/threads/ve-trasnmission-oil-return-line.248039/
The return line is the one closest to the centre of the engine.
Looking from your perspective from the front of the engine it is on the right hand side.
Did you top up the fluid to compensate for the cooler volume and any fluid lost?
This is left hand drive.


https://www.g8board.com/threads/self-perform-transmission-fluid-change.203090/
Drop pan, replace filter, refill, remove return line from transmission cooler place in bucket, start car in park, pump out 2 qts, key off, replace 2 qts, repeat as needed, follow gm procedure to set proper fluid level, done.