Chevy Colorado Diesel Forum banner

21 - 33 of 33 Posts

·
Registered
Joined
·
13 Posts
Ok guys, unless I missed something skimming through all the posts there is no mention on how to drain the old fluid from the torque converter.
Back in the 70's I remember draining the torque converter by removing the cover and pulling the drain plug on it. Some converters had a factory plug but most didn't which is why many either installed one or bought a aftermarket torque converter with a plug installed.
Now, if your just draining the fluid for preventative maintenance I can see no concern for leaving the old fluid in the converter. If your having issues or you are way behind on servicing them maybe it's a good idea to drain it as well.
 

·
Registered
Joined
·
2 Posts
@6speedTi from the searching I did, this 6L50 trans is treated the same as the Allison in the 6.6 dmax trucks. Drain and fill the pan is the recommended service. It introduces enough fresh fluid to mix with existing.
A flush is not needed unless there's a major maintenance issue or fluid is bad/contaminated.

Josh
 

·
Registered
Joined
·
161 Posts
Ok guys, unless I missed something skimming through all the posts there is no mention on how to drain the old fluid from the torque converter.
Back in the 70's I remember draining the torque converter by removing the cover and pulling the drain plug on it. Some converters had a factory plug but most didn't which is why many either installed one or bought a aftermarket torque converter with a plug installed.
Now, if your just draining the fluid for preventative maintenance I can see no concern for leaving the old fluid in the converter. If your having issues or you are way behind on servicing them maybe it's a good idea to drain it as well.
You can fill the pan, then run it with the return line located at the bottom of the radiator on the driver's side unplugged to collect more fluid. I did this, but not for too long. The fluid was so clean I decided not to bother. Drove it for awhile and then sucked out three quarts and put in the extra 3 I had and called it a day.

The connector is a standard C clip type deal. Remove the clip, give the return line a tug and slip a 3/4" plastic hose over the fitting and run it for a short time. Here is a direct link to my post in this thread showing that:

 

·
Registered
Joined
·
8 Posts
We have the exact same setup with the return line. Remove the black plastic skirt thing, which has four 14mm bolts and is easy to take off. The return line is on the bottom of the radiator, on the driver's side. We have the same quick connect shown in the video, a 3/4" ID hose fits snugly over the bolt as shown in my pic. Use a good pick like he did in the video, there is not a lot of tension involved on the clip, but you don't want to get it in your eyeball or have it fly off either just remove it carefully and orient it correctly putting it back on.

I decided the next day to do the return line trick and of course by then the system was cold. It initially flowed a bit (as shown in the photo) then stopped and I did not get much fluid (yes, the pan was full) only a slight drip. I think I blew it by waiting until the next day and suspect there is a thermostat involved, so it does not send fluid until it reaches a certain temp. Anyway, learn from my mistake and do it all while everything is warm. I gave up as I figured if I warmed it up again, the oil would all mix and defeat the purpose. If I am wrong about why I did not see fluid please enlighten me. :)

I gave up as the old fluid was barely dirty and I apparently screwed up by not doing it the day before when the system was warm. I plan to drive it for awhile and then suck out a measured amount of fluid later, and add back the same amount later to address diluting the old trapped fluid in the system with new fluid. I have way more oil than I need, will probably suck out 5 quarts to use it all, and it will basically be overkill, which is SOP in my world :LOL:

Bonus factoid - while under there, I noticed we do indeed have a drain cock on the bottom of the radiator on the passenger side. Woo hoo! I did not think we had one of those.



View attachment 8626 View attachment 8627
when you hooked up to the radiator line and tried pumping out the old fluid how did you manage to add the new oil the same time the old was coming out like he did in the video
 

·
Registered
Joined
·
161 Posts
when you hooked up to the radiator line and tried pumping out the old fluid how did you manage to add the new oil the same time the old was coming out like he did in the video
As long as you don't go insane and empty the transmission pan and run the intake of the trans filter dry, you can pump some fluid out of the return line without harm.

I did not get that much and thought at the time our trucks have a thermostat on the transmission (the bigger trucks do) and that is why I did not get much fluid, thinking it was not hot enough. Also, the fluid coming out looked quite clean, so I did not bother to follow up on it. Instead just drove it for awhile, sucked out a measured 3 quarts, put in three quarts of new fluid and called it a day.

Now looking back, I suspect that it needs to be in gear (with the parking brake firmly on of course) to pump fluid through the cooler. Someone correct me if I am wrong.

The Mobil 1 "LVHP" fluid I put in now has a couple thousand miles on it and the trans continues to work great. In any case, I would go with fully synthetic fluid, you can get any number of Dex 6 fluids that are full synth.
 

·
Registered
Joined
·
8 Posts
As long as you don't go insane and empty the transmission pan and run the intake of the trans filter dry, you can pump some fluid out of the return line without harm.

I did not get that much and thought at the time our trucks have a thermostat on the transmission (the bigger trucks do) and that is why I did not get much fluid, thinking it was not hot enough. Also, the fluid coming out looked quite clean, so I did not bother to follow up on it. Instead just drove it for awhile, sucked out a measured 3 quarts, put in three quarts of new fluid and called it a day.

Now looking back, I suspect that it needs to be in gear (with the parking brake firmly on of course) to pump fluid through the cooler. Someone correct me if I am wrong.

The Mobil 1 "LVHP" fluid I put in now has a couple thousand miles on it and the trans continues to work great. In any case, I would go with fully synthetic fluid, you can get any number of Dex 6 fluids that are full synth.
yeah I’m wondering the same thing if you have to have it in gear or hotter temperature. Hopefully someone has the answer. Did you use a 3/4 in clear . With a hose clamp on the return line?
 

·
Registered
Joined
·
161 Posts
yeah I’m wondering the same thing if you have to have it in gear or hotter temperature. Hopefully someone has the answer. Did you use a 3/4 in clear . With a hose clamp on the return line?
Yes, 3/4" ID hose. It fits tightly enough over the connector on the radiator, no need to clamp it.
 

·
Registered
Joined
·
8 Posts
Yes, 3/4" ID hose. It fits tightly enough over the connector on the radiator, no need to clamp it.
hey after you pumped it through the return line did you add the fluid through the return line connected to the transmission or through the fill plug
 

·
Registered
Joined
·
161 Posts
hey after you pumped it through the return line did you add the fluid through the return line connected to the transmission or through the fill plug
Through the fill plug using the hand pump.
 

·
Registered
Joined
·
8 Posts
Level ground.
Yeah when I pumped my oil out through the return line I did it cold and it came out fine did 2 quarts shut it off added 2 quarts then started it up and pumped another 2 quarts. Just got done replace every oil in the truck to amsoil anybody like there stuff
 

·
Registered
Joined
·
161 Posts
Yeah when I pumped my oil out through the return line I did it cold and it came out fine did 2 quarts shut it off added 2 quarts then started it up and pumped another 2 quarts. Just got done replace every oil in the truck to amsoil anybody like there stuff
Sweet! Amsoil is a great choice.
 
21 - 33 of 33 Posts
Top