I have a 2008 hummer h2 with the 6.2 liter engine .im loosing coolant some where and was wondering if there are any problems with the cooling system on these vehicles

With a cool engine remove the rad cap and run the engine for awhile and usually any air will work itself out.

Cooling System Draining and Filling (Static Fill)

Draining Procedure

Warning! In order to avoid personal injury, do not remove the cap or open the cooling system drains from a hot system. Allow the system to cool first.


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ImportantA 7.6 liter (8 qt) coolant container will be needed.

1. Place the coolant container under the radiator drain **** located at the bottom of the right radiator end tank.
2. Open the drain **** and drain the coolant. A small amount of coolant will drain from the system.


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3. Remove the surge tank cap from the surge tank and the coolant will drain from the system.


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4. For LE5 and LAT vehicles, if the engine block needs to be drained, a drain bolt is located near the bottom of the water pump assembly.
5. Inspect the coolant.
6. Follow the appropriate procedure based on the condition of the coolant.
• Normal in appearance--follow the filling procedure.
• Discolored--follow the flush procedure. Refer to Coolant System Flushing .

Filling Procedure

Caution! All entrapped air must be purged from the powertrain cooling system before the final coolant level can be determined. Proper coolant level is critical to avoid engine damage.
ImportantThe vehicle must be level when filling the cooling system.

1. Slowly add a mixture of 50/50 DEX-COOL antifreeze and clean water to the coolant surge tank. Fill the cooling system as indicated below:
• For LE5/LAT vehicles when the engine block is not drained, add 3.5 liters (3.7 qts)
• For LE5/LAT vehicles when the engine block is drained, add 6 liters (6.3 qts)
• For LZ4/LY7 vehicles, add 5 liters (5.3 qts)

2. Start the engine and check for leaks.
3. Run the engine and cycle the vehicle from idle to 3,000 RPM in 30 second intervals until the engine cooling fan comes ON, the engine cooling fan turns ON at approximately 102°C (216°F). Repeat this process twice before the engine is turned OFF.
4. Return the engine to idle, and idle for 30 seconds, then turn the engine OFF.
5. Allow the vehicle to cool, before adding additional coolant.
ImportantThe level in the surge tank will return into the cold fill range once the vehicle cools.

6. Add additional coolant to the surge tank until the level is approximately 13 mm (0.5 in) above the surge tank seam.
7. Install the coolant surge tank cap.
8. Hope this helps.

2.3L Engine

Specific to:
Ford Fusion 2008-2009
Mercury Milan 2008-2009

1. Raise and safely support the vehicle.
2. Drain the cooling system.
3. Loosen the 3 coolant pump pulley bolts.
4. Remove the accessory drive belt.
5. Remove the 3 bolts and the coolant pump pulley.
   1. To install, tighten to 15 ft. lbs. (20 Nm).
6. Remove the 3 bolts and the coolant pump.
7. Remove and discard the O-ring seal.
   1. To install, tighten to 89 inch lbs. (10 Nm).
   
   

Fig. Exploded view of the water pump-2.3L engine


To install:

1. To install, reverse the removal procedure.
2. Lubricate the O-ring seal with clean engine coolant.
3. Fill and bleed the cooling system

3.0L Engine

Specific to:
Ford Fusion 2008-2009
Mercury Milan 2008-2009

1. Raise and safely support the vehicle.
2. Drain the cooling system.
3. Remove the coolant pump belt.
4. Using Special tool 303-S455, or equivalent, remove the coolant pump drive pulley.

Fig. Using Special tool 303-S455, or equivalent, remove the coolant pump drive pulley

5, Disconnect the heater hose from the coolant pump.
6. Disconnect the coolant pump-to-engine hose and position aside.
7. Remove the 3 bolts from the coolant pump assembly.
8. Reposition the coolant pump-to-thermostat housing hose clamp and remove the coolant pump and hose as an assembly.



Fig. View of the water pump and related components-3.0L engine

To install:

1. Connect the coolant pump-to-thermostat housing hose and reposition the clamp.
2. Position the coolant pump assembly and install the 3 bolts:
   1. Tighten to 89 inch lbs. (10 Nm).
   2. Tighten the 3 bolts an additional 90 degrees.
3. Connect the coolant pump-to-engine hose and the heater hose.
   NOTE
   Install the coolant pump drive pulley flush with the end of the camshaft.
4. Using Special tools 211-185 and 303-S455, or equivalent, install the coolant pump drive pulley.

Fig. Using Special tools 211-185 and 303-S455, or equivalent, install the coolant pump drive pulley

5. Install the coolant pump belt.
6. Fill and bleed the cooling system.

One thing that could do all of that is a blown head gasket. That would allow the oil to mix with the coolant and the coolant to mix with the engine oil. Have to get it fixed right away or the engine will be trash.

There is virtually no difference between the Hummer H3 drive train and comparable GMC and Chevrolet drive trains. Although you overspent on a piece of pseudo-military jewelry, the drive train is reasonably reliable and easy to service, and parts interchange with GM truck parts.
My sole recommendation would be to use 15W-40 diesel-grade oil instead of the recommended oil and, if you haven't already done it in the last 20,000 miles, change all fluids (crankcase oil, brake fluid, transmission fluid, differential fluid, power steering fluid, engine coolant).

yes you can just drain all other coolant out completely

the ac compressor will come on and off frequently because the line pressure is below what it needs. your need to top up the Freon

Check coolant level, 95% is air in cooling system

1983 CHEVROLET TRUCKS C10 2WD PICKUP 5.0L 8-cyl Engine Code [F]

Cooling System, With AC Initial Fill..........17 liters
Cooling System, Without AC Initial Fill..........16.5 liters

Coolant, you can use the green or you can use the Long life coolant, just make sure you follow the instructions in the recommended mixture on the coolant information on the bottle. 50/50 water/coolant ratio.

Thank you for using FIxya.

firefighterf: not knowing exactly what engine of the three you could have in your car: 3.5, 3.9 and 5.3, I could only study up on technical service bulletins and recall some of the cars i have had in my shop with cooling system problems.
GM used "DEXCOOL" antifreeze which had a problem that caused corrosion and reeked havoc with the cooling systems on many of the vehicles they used it in. There was a service bulletin out on this matter to address a procedure in flushing the systems. There were quite a few cars which needed radiators, water pumps and heater cores replaced from the corrosive damage done by the DEXCOOL.
Check your car and make sure that you have not got a situation pending where the cooling system is fixing to leave you stranded or burn your engine up.
The V-8's didn't really have any problems with cooling systems which were mentioned in service bulletins other than that one.
The 3.9 liter had a problem with head gaskets leaking coolant. The leaks would appear to be coming from the top end(s) of the cylinder head(s), leaving small deposits of coolant on the ground after sitting. A new gasket design came out to resolve the problem.
The 3.5 had a problem with head gaskets as well and additionally a problem with leaking "crossover " pipe gaskets.
Add this to the issue with the corrosion problem of the DEXCOOL and you have a serious situation. Keep in mind, that often people open the radiators or cooling system recovery tanks when they might still have some pressure in them. Coolant spills or sprays around the immediate area, including near the "FAN GROUND LEADS". If you end up with poor grounds, you will develop problems with any electrical components which rely on those ground circuits. NOW! Here is some more food for thought that few techs have ever told customers. A coolant temperature sensor is designed to be immersed in coolant or water. The heat transferred from the water or coolant to the temp sensor, causes the sensor to change resistance values which in turn, will make relays go on an off, give input to the ecm for it to use as part of the data needed to control pulse width of the injectors, and guages indicate the temperature. One phenomenon that occurs when the coolant level drops to where it no longer has the coolant sensor immersed, is that the sensor will no longer read correctly. You temperature guage in you dash may indicate the engine is at normal operating temperature and the engine may be in thermal nuclear melt down!
Steam in the cooling system will not have the same effect make the sensor register hot!
I hope that I may have given you some direction in which to look.
My not knowing the particulars, I tried to cover as many bases as I could other than dealing with relays, fuses and wiring. I would need the specifics on YOUR car to be able to better assist you.