I have a 99 Chevy Suburban, 3/4 ton 7.4L it was leaking coolant and I traced it to a T connector between some hoses and while removing it I noticed the heater control valve connections to the house were broken/cracked as well so I removed that. Unfortunately I too late realized I had taken off too many hoses for it to be obvious how it all hooked back in. I thought I knew and drew myself a diagram of what I remembered, but I think I may have connected something wrong because the car overheated and was blowing coolant around these clamped hoses. There is a picture of the control valve here: http://www.rockauto.com/catalog/moreinfo.php?pk=84579 The two lower connectors (in the diagram) hook to hoses through the firewall presumably to the heater(s), and I'm sure I got those right. The other side I may have backwards but before I take it apart and try it perhaps someone can simply solve for me. What hose should go to the top (right side of the picture) connector, should it be the heater hose connected to the radiator or should it be the hose coming off the engine?

gmc and chevy k1500 pickup and suburban years 95-99
k2500 pickup years 95-98
k2500 suburban 95-96
gmc k2500 and yukon 95-98
I hope that helps if so please rate my answer

drain the coolant from radiator remove upper hose from thermostat housing clean housing and block install new thermostat with the spring end toward the block pointed to radiator use a new gasket and a small amount of gasket sealer when tightning the bolts back on the thermostat housing be sur to run them down evenly or you will crack the housing reinstall hose add coolant start and check for leaks

my guess is that there is a leak in the heater core and the hoses have been disconnected to save loss of water

Drain Coolant ,2 bolts in 2 hold down brackets on top of rad ,remove bolts for shroud.remove rad hoses.the rad should lift out

1. Write down your radio code if it has some anti-theft device.
2. Allow the engine to cool down for about 3-hours before the start of this operation.
3. Open the hood, and disconnect the battery negative terminal. Tuck the negative terminal aside so it won't flip back.
4. Locate the radiator drain-plug (plastic wing-nut) on the lower back side of the radiator, and turn it backward to remove it.
5. Place a container under the radiator to catch the anti-freeze coolant.
6. Remove the radiator cap.
7. Once the coolant is drained, trace the upper radiator hose to where it ends on the engine(thermostat housing), and remove the hose with a medium size plier.
8. Loosen the three bolts holding the thermostat housing. Gently take out the housing.
9. Notice the position the thermostat was previously installed.
10. Replace the old thermostat, and the o-ring around it. Clean its mounting area. Notice that the o-ring fits around the thermostat.
11. Replace the thermostat housing and torque the three bolts to 78-inch pounds. Replace the upper hose.
12. Replace the radiator drain-plug.
13. Re-use the antifreeze coolant and be careful no dirt goes in with the coolant into the radiator.
14. Return the radiator cap.
15. Reconnect the negative battery terminal.
16. Start the car and check for leak.

Important: Anti-freeze coolant harmful to the environment. Return unwanted anti-freeze coolant to collection areas.

I would not worry about antifreeze in the transmission. The pressure in the tranny cooler will not let any coolant get in. If it was leaking you would have tranny fluid in the radiator. You may have some freeze plugs that have pushed out or a cracked block or some coolant passage above the transmission. Get it pressure checked

most of the time this wont be the case ,,,this has a ht6 compressor,bad to leak,,look for low freon levle and check low presure switch and high presure switch and connector,high side switch is on back of compressor,check to see if bad connector or bad switch/these are in series with one another ,before clutch activation

first check the exhaust... if it is white you have a blown head gasket.... next issue may be a stuck thermostat next place to look is the water pump, there is a "weep" hole on the casting, if that is leaking you will need to replace the water pump

if it is ATF then it is the trans pump or input shaft seal, these both require the removal of the transmission.

If it is coolant it may be a rear freeze plug, but this is rare and also requires the removal of the transmission

A more likley cause is a leaky intake manifold which is very common on the vortec v8 engines, it leaks at the very back and runs down the bell housing. this repair is a bit extensive but can be accomplished by a good DIYer given time, space and tools this repair is also the least expensive of the three, about $300

i assume thru the rear cover? Remove cover and check for spider gear shaft pin being broke.While in there of course inspect all gears but pin most prone