Automatic Transmission 4L60E fluid flow

[DanX]

Chevy Silverado LT 1/2 Ton 5.3 ltr V8

 

I am wanting to do a simple fluid flush to get all of the old ATF that I possibly can out of my 4L60E transmission. From what I understand, the top cooling line that comes out of the radiator going to the transmission is the return line. For me to do the job correctly I need to know if that return fluid goes directly to the oil pan when it re-enters the transmission.

 

Also can you please tell me if there will be any harm to the transmission if I have the cooling return line open and dry while idling the transmission, as long as I keep the fluid level up in the pan.?

[Carder09]

To drain all the fluid out and put in new would lessen the life of that tranny; unless you have been on the dot with scheduled tranny fluid and filter replacements, then I do not recommend doing the above.

[DanX]

I bought the truck at 50k miles. Changed filter and pan oil at 60K then now again at 111k miles. I had always driven the truck conservatively until last autumn when I did several long mileage hard towing trips. When changing out the pan oil this time the oil looked very dark. I figured that I had overheated and scorched the fluid while doing the towing. After I changed filter and put in 5 qts fresh fluid, it felt like the transmission was performing much better like it was gripping very positive. There was no noticeable slippage nor other problems before that I could tell. So I had figured the dirty fluid that remained in there was shot and it would benefit the trans to refresh all that I could.

[Carder09]

You can change if you like, but still not recommended. Better if you frequent filter and small TF change rather than all out

[gmtech4]

You can change if you like, but still not recommended. Better if you frequent filter and small TF change rather than all out

 

 

+100

 

sorry Dan but you are buying into the hype of a "flush"

[txab]

Follow this procedure and you'll be fine

 

http://www.gmfullsize.com/forum/showthread.php?t=179148

[DanX]

You can change if you like, but still not recommended. Better if you frequent filter and small TF change rather than all out

 

 

Thanks for everyone posting. I really appreciate all responses.

Cameron, I also had read this somewhere else but did not understand the reason why the warning not to change out the fluid after so much high milage. So I did some more searching and found in another forum this reason -

 

Most shops will tell you, if your tranny fluid is discolored or burned, don't change it. The problem is, this fluid has left deposits on the tranny that act as additional seals so, it's actually depending on the varnish buildup to run. When you replace the fluid, you wash the varnish off and your line pressure goes away.

Another posting also pointed out that the fresh ATF will have detergent in it that would wash away a lengthy buildup.

 

Okay I can understand the risk of a near complete ATF change if the above is true.

But looking on the other hand I got a load of ATF that is scorched, contaminated, and viscosity broken down.

After further searching and reading I realize that my recent 5 quart ATF & filter change had restored some of the viscosity to my trans fluid which is why I noticed some nicely improved shifting. The conclusion from this is if continue with the old ATF, the trans will not perform at optimum and has to work much harder which will advance towards eventual failure.

 

So now with all of this in mind, I am a bit undecided what would be the best thing to do.

 

http://www.ehow.com/list_6030986_causes-dark-transmission-fluid_.html

[DanX]

Follow this procedure and you'll be fine

 

http://www.gmfullsiz...ad.php?t=179148

 

 

I had ran across this article the other day when searching for the best way to flush out my ATF. Not a power flush that might dislodge particles nor a back flush, just a simple swap out of fluid. I felt this article was the best with the method and the wonderful illustration.

But notice the date of the article posting. 2009. Almost three yrs old.

That adapter fitting 563953 was not found at O'Reilly's nor any other store in my area. Maybe that brand was discontinued at some point.

What I had found that might replace it is a Dorman Part # : 563953BP.

 

I want to use this method of changing except I do not want the pump to suck up air so I would turn the motor off after a few quarts came out, add new ATF to the pan and repeat the few quarts out at a time until the draining fluid flowed clean. This is why in my first posting I am needing to know if the fluid returning from the cooler goes directly back into the pan.

[elcamino]

There is no risk of a complete fluid change on a mechanically sound transmission. I have done it many times over the years. You have to R & R the filter before you start to R & R the ATF. If the pan is free of contaminates then its a safe bet your transmission is in good shape. You fill the pan then disconnect the top line coming from trans and direct flow into a 5 gallon pail while adding new fluid.

 

Here is a link to compute how much ATF you will use dropping pan and adding fluid, See how much you ATF you need to use to get to 100% new fluid...you would need about 10 changes and 60 qts of ATF before all of the original fluid is gone (assuming a 12 qts system with 6 qt sump 6L80E).

 

LINK

 

PS - I did not come up with this ss, someone else made it and shared it.

 

How to do a complete ATF Change over

[Black02Silverado]

txab pretty much summed it up well. That is cool link on "how to".

[hogwildmike]

Chevy Silverado LT 1/2 Ton 5.3 ltr V8

 

I am wanting to do a simple fluid flush to get all of the old ATF that I possibly can out of my 4L60E transmission. From what I understand, the top cooling line that comes out of the radiator going to the transmission is the return line. For me to do the job correctly I need to know if that return fluid goes directly to the oil pan when it re-enters the transmission.

 

Also can you please tell me if there will be any harm to the transmission if I have the cooling return line open and dry while idling the transmission, as long as I keep the fluid level up in the pan.?

 

You'll be fine brother. If I were you though, I'd take it somewhere and have it done. Preferably to a place where you know they do good work.. a place you know that, without any doubts, will do it correctly.

 

I've had my 05 Silverado Crew-Cab 5.3 Vortec/4L60 trans since 2005. I didn't change the trans. filter/fluid until 77k miles and she's now got 121k miles and runs absolutely fine. Now, I didn't have it 'FLUSHED' - which I wouldn't recommend AT ALL.. for serious reasons. However, a simple fluid/filter change won't hurt anything brother. And trust me, your transmission will thank you. IMPORTANT: DO NOT OVERFILL transmission with fluid.. and try your best to not underfill it.

 

In a nutshell.. just remember to never fall for the "trans flush" procedure... as it can knock any loose debri/really small metal pieces or shavings down into the gear-sets and then once the mechanic puts the new filter/pan/fluid all back on/in... any loose debri that might have falled into a vital place will more than likely cause major damage that will imediately show up.. or might show up fairly soon down the road. Basically, its just better to not do the "flush".

[Carder09]

Well I am no expert on transmissions but that link seems promising. If you want to then go ahead and chance the.new.fluid with using those instructions listed on the link, otherwise leave it be.