My 2008 H3 Base Hummer has 35000 miles on it and I changed the transmission fluid last weekend. I previously installed an inline transmission filter between the transmission and the radiator cooler, so I started by removing the cable clamp, and starting the vehicle and letting the transmission pump the fluid out (and shut the car off once the fluid was sputtering out). Only about 5 quarts came out and it was much darker than I expected. To get the rest of the fluid out, I poured fluid in the filler tube and repeated the process. After about 10 total quarts were installed, I started to see clean fluid being pumped out. It took a couple more quarts to top it off, and I think I pumped out about 12 quarts. I'm not sure what the capacity of the transmission is, but I think it's 12-14 quarts.

Afterwards, I test drove it and it simply felt better, shifting less often, and not hunting for a gear when going up hills.

Also, the inline filter that I installed has a temp sensor. Prior to the fluid change, the temperature would regularly be in the 170 deg F range. Now it is in the 130 deg F range. Simply by changing the fluid, the transmission is running 40 deg cooler.

I would suggest everyone consider replacing the fluid earlier than what the service manual states (50K mile).

The only reason I changed the fluid was to prepare the H3 to tow my RV. It's 3500 lbs, and I know I'm pushing the vehicle so I have changed all major fluids (diffs, transfer case, and transmission).

Dale

 

There's a machine that the dealer uses to flush the system. Properly. Some things are worth paying for to be done right.
I worked as a tech for more than ten years and never would anyone just crack a line and let the trans pump the it's fluid out.

 

I'm curious about this. Back when I was wrenching, we would drop the pan, r&r the filter, install the pan, refill and go. If the pan fluid was real bad, we'd sometimes drain the torque converter using it's drain plug. I would think running an auto tranny dry would be bad on o-rings, clutches, and generate lots of heat and premature wear. Have things changed?


WGW

 

Things haven't changed in that regard. Running them dry like that is just foolish. They are touchy enough as it is.
If your just going to quick change it then drop the pan, Otherwise spend a buck fifty and get it done right. Actually come to think of it, that is the only thing I've had the dealer do that wasn't warranty work.

 

I'm not understanding what you mean by "running it dry." Do you mean dry as in, he drained it completely dry then ran it? From what I'm reading, he drained what he could from the tranny, then did a "drive-way flush" by continuosly filling with clean fluid until all the dirty fluid was gone, leaving only clean fluid.

Just curious is all.

 

I shut it off when it started sputtering. This is a method that has been used by many other people, not just me, with the same 4L60E transmission. Dropping the pan is foolish unless you just want to change 40% of the fluid. You have to use other methods to get it out of the torque converter.

Knock the method all you want, and get the job done anyway you want. I'm simply saying that it's worth doing.

Some things are worth doing right, that's why I do it myself.

Dale

 

Screw doing the fluid change, just buy a new hummer!!!

 

zzpw3x,

I'm curious about the trans. filter you installed. I've briefly browsed Summit but none of theirs has a temp. sender if I remember correctly.

 

I used the Perma-Cool 10677. I think it's available through Jegs and Summit.

 

Thanks Dale
I flushed the fluid in the tranny at about 22K. Dropped the pan, changed the OEM filter/gasket. Refilled with the Amsoil Low-Viscosity ATF which is a direct sub for the DEXRON-VI. After the intial fill which worked out to be about 1 gal., I flush ran it much like you did using the tranny hoses that go into the bottom of the radiator. I just didn't turn the truck off. I put a spigot on the 2 1/2 gal. jug of new fluid, turned it upside down in the fill tube, made a vent hole, put a home depot pail under the unhooked hose and in went the new and out went the old. I made sure I shifted it through all the gears while it was flushing just to be sure. Like yours, old fluid was noticably darker than the new (you think the orange pail would of helped make it look better) so who knows how it would of looked if I waited till 50k like the manual tells you. Happy I did it so its one less thing to do for a while and I like Ben Franklins an ounce of prevention is worth a pound of cure theory.
Thanks for the filter/sender info and for starting this thread. I'm sure people will benefit from it by keeping an eye on their tranny knowing they might not want to wait for the reccomended service interval.