08 Transmission Flush

[Mossyoakglock]

I am going to do the transmission flush this weekend that is outlined over at GMFS ( http://www.gmfullsize.com/forum/showthread.php?t=179148 ) but have a question on which line I need to disconnect. I am going to buy the fittin also. In one of the posts somebody with another GMT-900 said that the top fitting on the passenger side is not the correct fitting to remove. Is this the return line?

 

If that is not the correct fitting to remove, where is the correct fitting located? Im going to do this this weekend so I want to make sure this in the correct fitting on the GMT-900's since the write-up was done with an 07 GMT-900.

[dlstewart01]

I don't know if it really makes that much difference. The trans fluid is circulated through the cooler and back to the trans. it just makes a circle. You will know real quick when you start the engine.

[Mossyoakglock]

That's what I was trying to avoid. When I remove the fitting I'm going to be replacing it with another fitting with a clear tube on the end so I can see when the fluid starts to come out and I need it to be the fitting that when it's connected to the radiator like in the write-up it will pour into the bucket. Supposedly that's the top fitting on the passenger side. Make sense?

[dlstewart01]

GM return line location

 

http://www.txchange.com/cooler.htm

 

That would be the top line on the trans. Just follow it to see where it goes...

[txab]

If you have a secondary cooler in front of the rad. then you can easily figure out which line is the output. From trans to rad to secondary cooler to trans. It's really pretty simple. And it should be the upper.

 

Edit: If you're wanting to flush the secondary cooler then you'll need to disconnect the line from the secondary cooler, which will require removing the grille.

[Mossyoakglock]

Edit: If you're wanting to flush the secondary cooler then you'll need to disconnect the line from the secondary cooler, which will require removing the grille.

 

If the radiator and trans cooler are all connected to each other, then if I just remove the main return line on the top it will flush out everything in the system, both the rad and coolerm, and will push new fluid through the whole system, correct?

[txab]

Edit: If you're wanting to flush the secondary cooler then you'll need to disconnect the line from the secondary cooler, which will require removing the grille.

 

If the radiator and trans cooler are all connected to each other, then if I just remove the main return line on the top it will flush out everything in the system, both the rad and coolerm, and will push new fluid through the whole system, correct?

 

 

You understand you have a cooler in the radiator. Then you probably have a secondary cooler behind the grille. You may not. The top fitting on the radiator is the output to the secondary cooler. After fluid goes through the secondary cooler it heads back to the trans.

 

So that means if tap the top fitting, you'll be leaving a few ounces in the secondary cooler. To me it's no big deal and I wouldn't worry about it. On my truck I have a larger aftermarket secondary cooler and I can easily remove the return line from it and flush.

[Klink]

Does anyone have a part number or size on that thread that goes into the radiator?

 

I too am going to flush on my own and I would like to get that brass fitting.

[tonygxp]

by the time you're done it would have been worth taking it a trusted shop and having them hook it up to the machine. go where they use the BG chemicals (BG warranties your trans by using their chemicals and saving the receipt btw) and machine, it's worth the money, i've used it a bunch of times at my friend's shop people get it done all the time and works well. what'll cost ya? another $100? even if everything goes well it'll take you at least a few hours, the mess afterwards, no warranty, etc. just my $.02 but certain things i do, certain other things i bring it to the shop for because of the possible complications. good luck.

[Klink]

It might be just me but once my car gets a certain amount of miles on it, I only want my hands on it.

 

So, anyone know the thread size on that fitting?

[txab]

It might be just me but once my car gets a certain amount of miles on it, I only want my hands on it.

 

So, anyone know the thread size on that fitting?

I think the link in the first post tells you everything.

[Klink]

Aw Crap. You're right. I was looking at that huge label on the bucket and I was thinking that was for the tubing. Might help to actually read it I guess. Don't know how many times I looked at that.

 

Time to stop drinking I guess.