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Discussion Starter · #1 · (Edited)
Wondering whether you should flush your trans if you don't know its history? Read this first.

Updated 7/16/2020: TL;DR / Bottom Line Up Front:

  • Disconnect one of the trans cooler lines near the battery. Put a clear hose on the hard line and then start the car to pump out the pan. Shut off when it stops flowing. It won't hurt the transmission to suck air for a few seconds.
  • Drop and clean the pan and magnet, replace the filter, reinstall the pan. Torque is 8 ftlbs, don't overtorque.
  • Refill transmission with new fluid (the same amount that first pumped out).
  • Then repeat the flush procedure until the fluid in the clear hose turns color (you'll see it, usually by 10.5 quarts). Use clean empty gallon milk jugs to catch several quarts each time. Check the dipstick regularly every 50 miles to see if the new fluid picks up more grit. If it does, flush it again. If the fluid stays clean, you're done.

Detailed steps:
  1. Jack up the car, EDIT - unless your car is lowered, you likely don't have to jack it up. Just get to a point where you can reach the hoses below. You can avoid jacking the car if you can slide a pan underneath to catch the fluid.
  2. Disconnect the cooler line at the one joint near the battery where there's a hose clamp.
  3. Put a short length of tubing on the hard line, and aim it into a bucket or a pan that holds at least 4 quarts if you have a stock pan, or 6 quarts (1.5 gallons) if you have a deep pan. Don't worry, no fluid will come out of the rubber hose you disconnected. I'm now using milk jugs as catch cans with the stock trans pan and have never overfilled one yet.
  4. Start the car.
  5. The engine running will drive the transmission pump, which will pump all of the fluid out of the pan for you.
  6. When the flow out of the hose starts to sputter, shut the car off so you don't damage the pump.
  7. If you're OCD, wait a minute for any residual fluid to drain into the pan so it can get to the filter, then run the car a few more seconds. You should be able to get around 3-4 quarts of fluid out using this method.
  8. Now, the pan will be nearly empty (maybe 1 qt remaining in the pan) and you can change the filter and clean the pan if you want to. If you find metal chips or chunks in the pan, start saving for a rebuild. Dust is ok.
  9. Measure how much you pumped out, refill the same amount of new fluid back into the transmission.
  10. Repeat steps 4-9 until the fluid color changes to the new fluid.
  11. Now your transmission is flushed out.
A 4L60E transmission, a stock-diameter (12") torque converter, and alll of the assorted cooler lines and coolers holds 11 quarts. You will not be able to pump all of this out in one shot - the pump will drain the pan dry and you will have to add 4-5 quarts of new fluid, then continue pumping until the fluid coming out of the cooler line changes color. It will be visibly obvious. I started seeing clean fluid come out of the hose at around 8 quarts after having cleaned the pan and installing a new filter.

If you want to flush out your cooler lines while the transmission is out of the car, go buy a can of Kooler Kleen or equivalent from Napa and blow the lines out both ways, then finish off with compressed air. Do this ESPECIALLY after you've had any sort of failure in the transmission, whether a worn-out 3-4 clutchpack or a hard part failure.

A picture of the drain setup is shown below:
 

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I have used this method for the past 4 years, and it is the way to go. I normally un do the lower cooler line at the rediator. But that is a slight difference.

Works great! No more fighting the fluid flilled pan on your back.
 

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Nice post Joel, it don't get much easier than that! Better yet, a guy can also drain the pan that way, instead of getting a bath of tranny fluid! :cool:
 

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Am I the only one with a bolt in my tranny pan? Just like oil for me, I unscrew let it drain then take down the empty pan... Was this bolt just added on by previous owner maybe?
 

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Am I the only one with a bolt in my tranny pan? Just like oil for me, I unscrew let it drain then take down the empty pan... Was this bolt just added on by previous owner maybe?
They weren't factory.
 

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  1. If you want to flush out your cooler lines while the transmission is out of the car, go buy a can of Kooler Kleen or equivalent from Napa and blow the lines out both ways, then finish off with compressed air. Do this ESPECIALLY after you've had any sort of failure in the transmission, whether a worn-out 3-4 clutchpack or a hard part failure.


  1. what is Kooler Kleen?? is it a aresol or pressurized some how? if not how do u "blow the lines out" the first time b4 u used compressed air?
 

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>>Mess21

It's an aerosol pressurized can

Product Description

This convenient oil-based solvent saves time and money for general service and repair shops. It will prevent contaminating new or rebuilt transmissions you install. The flush can is used to prevent transmission contamination by removing and eliminating contaminants such as grease, dirt, sludge, grime and metal shavings in transmission cooling systems and lines, without leaving any water or soapy residue in the system. It also cleans electric parts, wire harnesses, etc. leaving a thin layer of dielectric protectant.

 

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  1. Jack up the car.
  2. Disconnect the cooler line at the one joint near the battery where there's a hose clamp.
  3. Put a short length of tubing on the hard line, and aim it into a bucket.
  4. Have a friend start the car.
  5. The engine running will drive the transmission pump, which will pump all of the fluid out of the pan for you.
  6. When the flow out of the hose starts to sputter, shut the car off so you don't damage the pump.
  7. Wait a minute for any residual fluid to drain into the pan, then run the car a few more seconds.
  8. Now, the pan will be empty and you can change the filter if you want to.
  9. Measure how much you pumped out, refill the same amount of new fluid back into the transmission.
  10. Repeat steps 4-9 until the fluid color changes to the new fluid.
  11. Now your transmission is flushed out.
If you want to flush out your cooler lines while the transmission is out of the car, go buy a can of Kooler Kleen or equivalent from Napa and blow the lines out both ways, then finish off with compressed air. Do this ESPECIALLY after you've had any sort of failure in the transmission, whether a worn-out 3-4 clutchpack or a hard part failure.
I just wanted to say thanks for this info! I did steps 1-9 to do a filter change. Man did that avoid a mess. I had a little trouble coaxing the rubber cooler line off the hard line, but patience prevailed.

There was a little fluid left in the pan when I dropped it, but I took my time bringing it down so no problems there. The only mess was from the drips coming off the internals of the trans once the pan was off, but I had some cardboard underneath to catch the drips.

The rest was a cinch!
 

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Discussion Starter · #10 ·
FYI to all: This is linked from the Links thread at the top of this section.

I would also recommend you change your fluid at least yearly. The detergents in Automatic Transmission Fluid (ATF) tend to hold dirt and gunk in suspension (until there's so much that it overwhelms the detergents and falls to the bottom of the pan). The best way to get that out is to completely flush your fluid each year. It's way cheaper than a rebuild.
 

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Wear old clothes, because they will be permanently stained. I put a big piece of cardboard under the car to catch the drips, because they just kept falling.

Loosen all the bolts holding the pan to the transmission. There will still be a little fluid in the pan, so hold it level as you take out the last couple of bolts.

These instructions are for trucks, and talk about a drain plug in the pan, but they're close enough:
http://www.gm-trucks.com/resources/...the-fluid-and-filter-on-a-4l60e-transmission/

Discussion on how to remove the filter seal:
http://www.impalassforum.com/vBulletin/showthread.php?t=241282

Autozone sold me a kit that had a replacement filter, filter seal, and rubber gasket seal.
 

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>>Mess21

It's an aerosol pressurized can

Product Description

This convenient oil-based solvent saves time and money for general service and repair shops. It will prevent contaminating new or rebuilt transmissions you install. The flush can is used to prevent transmission contamination by removing and eliminating contaminants such as grease, dirt, sludge, grime and metal shavings in transmission cooling systems and lines, without leaving any water or soapy residue in the system. It also cleans electric parts, wire harnesses, etc. leaving a thin layer of dielectric protectant.

Can Brake Clean be used as a substitute ?
 

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Joel-
What are the thoughts of changing fluid when the previous service is unkown?

I have owned the car 3/4 years and put 20000 on it. I have never changed it nor do i know if Craig (key motors) did before i bought it...
 

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Discussion Starter · #16 · (Edited)
If it was a 9C1, change it. It's likely the PD has changed the fluid at least once.

My police-owned 9C1 had way better maintenance than my civilian-owned Roadmaster wagon.

UPDATE - please see this thread regarding whether you should change your fluid if the history is unknown or it's never been changed.
 

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Discussion Starter · #19 ·
Parts store brand Dex/Merc3.

The following is courtesy of Gregg Nader of Sonnax:

Note that GM has pulled the licenses for Dexron 3 / Mercon because companies were using base stocks for the additive packages that were not meeting spec over the long term. That's why you can only find names like "DexMerc3." The fluid is still suitable for the 4L60E.

If you can find synthetic fluid, you will get a much longer time until viscosity breakdown.
 
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