Transmission Flush Complete!
So I performed my transmission flush this past weekend and just wanted to post my process and any information that could possibly help someone in the future.
I started by first figuring out which method I wanted to use. I decided to use BusDriver's method in this thread and perform a flush by disconnecting the cooler return line from the rear of the transmission behind the driver side wheel.
You can see in the first pic below (taken by BusDriver in his post), when you take the driver side wheel off, the return line connection is basically jumping right at you.
![Auto part]()
Because I wanted to easily and accurately measure the fluid that was coming out, I purchased one of
these from Amazon. Since our transmission holds about 9 quarts of fluid, this container was plenty to catch everything.
Now that I had my line picked out, catch container picked out, all I had left to do was to figure out an accurate way of measuring the trans fluid temp, and find the correct tube to attach to the trans cooler line.
Based on the advice from Andrei (XtremeRevolution), I purchased one of
these bluetooth OBDII adapters as well as the
Torque App to measure my trans temp since correct fluid level is dependent on accurately knowing your trans fluid temp. This thing is awesome by the way, and one of the best things I've bought for my car.
Finally, it was time to decide what size tubing to use. Based on the design of the trans return line, I wanted to get my tubing
over the flare that is on the tube, so that I can use a hose clamp after the flare to hold the tube onto the line. I found
5/8" I.D. clear plastic tubing to work best (see pics below)
Now that I had everything prepared, I was ready to begin my flush. I started by removing the driver side tire and leveling the front of the car so it was completely level. I also made sure that I was able to crack loose the level plug for later.
Next I loosened the 13mm nut holding the cooler line retaining block to the transmission and pulled the cooler line out of the rear of the transmission. *Note, it was a little tough to remove the line. I found pulling the line back and towards the left (driver side) helped get it out.* It's also worth noting that
almost no fluid came out when I pulled the line out (which was something I was worried about.)
Now I slipped my clear tube over the trans line (see below) and secured it with the hose clamp. The hose clamp was a 1" clamp I believe.
![Fuel line Auto part Pipe]()
Next, I had my ran my tube into my quart container and got my 10 quarts of
Amsoil transmission fluid ready to pour.
![Automotive exterior Bumper Auto part Gas]()
I inserted my long neck funnel into the top fill port of the transmission and had my helper start the engine. The fluid started coming out immediately in the clear tube and into my container. The fluid was black as sin because of the anti-corrosion agent GM put in.
I began to pour immediately and tried to keep up with the transmission. The fluid came out a little fast until the engine idle rpm normalized. Once at a normal idle, the fluid came out at about a quart every 10 seconds. Definitely easy enough to keep up with pouring.
After about 8 quarts, the fluid was starting to come out clear, and after the 9th quart, the fluid was nice and clear so I had my helper shut the engine. I finished pouring the last drops of the 9th quart and then removed the clear tube and began to re-attach the cooler line to the transmission.
It's also worth mentioning that I bought a
replacement o-ring for the trans cooler line where the flare seats onto the transmission case. It's so cheap that I figured why not.
The whole flush process took about 90 seconds, and I couldn't believe how easily it went.
Finally it came time to check the level. Per Andrei's instructions in this thread, the fluid must be between 85C - 95C before pulling the level plug. To accomplish this, I put my foot down hard on the brake (still with the tire removed and up on the jack stands) and first cycled through all the gears two or three times to get any air out.
Please make sure your car is securely jacked up and back wheels locked and chocked as shifting through gears makes the car shake a bit.
After cycling the gears, I shifted my trans into M3 and began power braking while keeping an eye on the temp with the torque app.
I tried to keep it between 2000-2500 RPM and I'd say it took about 3 minutes to reach 90C (195F). Once I hit 90C, I let off the gas and let the car idle. I quickly removed the plug and a bit of fluid came out. Be prepared to have a towel ready and some gloves since the fluid will be literally almost 200 degrees. Removing the bottom splash shield will allow you to easier catch what comes out. I should've but didn't and now have a nice stain on my driveway...
:yahoo:
After letting about 1/4 of a quart out, the fluid began to extremely slowly dribble out.
I made sure the car was still at the right temp and reinstalled the fill plug to complete the job.
I performed my flush at 34,000 miles because I am tuned and firmly believe in preventative maintenance. I know it may have been a bit early, but I just bought out the car from a lease and I wanted to get some high quality fluid into the transmission asap.
The car shifts much smoother. It already shifts extremely fast from the BNR tune, but now with fresh fluid, I sometimes can't even feel it shifting it's so quick and smooth. I'm very happy I performed the flush and definitely recommend it for keeping your transmission happy.
Good luck everyone!
