This weekend I have intentions of doing my plenum gasket, new cap and rotor, and programming my truck with my SCT tuner. I was reading the instructions on the plenum and I had intentions anyway of doing a coolant flush. Now I propose a couple questions, now on the passenger side of my radiator, I see lines labeled "Transmission" my best guess I have the factory transmission cooler. (Better than nothing for now I guess). Now with my coolant flush, I intend to take out the petcocks and drain it that way and flush it out with the hose for a couple minutes, now in this process, does this drain/flush all of the coolant out of my transmission? I'm not too sure on how that whole setup works, which is why I am asking. My method is, if I'm going to do it, might as well do it right. I was contemplating on using a coolant flushing cleaner as well, does anyone recommend any specific brand? Thank you in advance.

 

There should never be any coolant in the transmission if everything is working properly. Your transmission is cooled by circulating its fluid through a capillary style coiled tube that sits in the tank of your radiator. Engine coolant cools the transmission fluid in the tube and the cooled fluid returns to the transmission. You also may have an auxiliary transmission cooler (that's separate from the radiator) that also cools the transmission fluid. Air passing through that cooler is what cools the transmission fluid as it circulates through the cooler. Here's a link to help explain it better than I can:

http://auto.howstuffworks.com/auto-p...n-coolers1.htm

 

coolant, oil, and transmission fluid run close to each other but never mix. each has its own path.

radiator contains a coolant section and a small transmission fluid section.
engine contains a coolant section and an oil section.
transmission contains transmission oil only.

drain and flush coolant by removing radiator drain plug on drivers side. its sort of tricky. turn 1/4 turn, pull out, turn another 1/4 turn and it will come out more, including all the way out. careful of o-ring. you can further drain the engine block (good idea) by removing the hex head pipe plugs on each side, close to the engine mounts. they are awkward to get a socket or wrench on, don't round them off.