Radiator Flush
 

Hello, I have a 2004 Blazer 4x4 and would like to know if anyone can help me out with the proper procedure for emptying the radiator to replace the Dex-Cool engine coolant. I am unable to find a drain valve with the exception of something that might be the drain valve on the bottom right hand side of the radiator. However, what seems and might be a drain valve appears to require a special tool to open it and is almost imposible to get at. Thank you very much in advance to anyone out there who can help me.

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** Moved to Engine & Transmission **

GM used a couple of different styles of drain valves, you might have one that requires a 1/4" drive extension to remove it. Your 2004 requires Dexcool coolant, ethylene glycol is NOT recommended. Originally GM instructed to flush every 5 years or 150K miles, that's not nearly often enough. If you wait that long, you will have problems. It needs to be done at least every 3 years or 36K miles. Draining and refilling the radiator alone is a waste of time and money. To properly flush the cooling system, each component needs to be flushed separately, i.e. radiator, engine block, heater core, coolant reservoir.

Heater core:
Remove both heater hoses from the engine, hang one over the fender, (to prevent a mess) and flush the other hose with a garden hose until it comes out clear. Switch hoses and repeat until it comes out clear, then reinstall the hoses to the engine.

Engine block:
Remove both heater hoses from the heater core, the lower hose from the radiator, and remove the thermostat. Flush into each hose and into the thermostat outlet in the intake manifold, until it comes out clear at the lower radiator hose. Reconnect the heater hoses, and reinstall the thermostat.

Radiator:
Remove the upper radiator hose from the radiator. Flush in both directions through the radiator until it comes out clear. Reinstall both hoses to the radiator.

Coolant reservoir:
It's easier to remove it from the vehicle, then clean it out.

If the cooling system is really nasty, use a strong mixture of TSP and water, then drive it for ~20 minutes and repeat the above steps until it's clear.

Refill with 50/50 Dexcool/distilled water, (not tap water) & "burp" the air out.

Thank you Captain Hook, I will follow your recomendations for flushing out my cooling system. However, there is one thing which I am not clear on and that is the issue about the a drain plug on the engine block which you did not mention. Do you recommend that I remove it?, That is if I can find it, it is apparently under the exaust manifold on the drivers side. Thanks again, Bert04

There are 2 drain plugs: driver side you can access through the wheel well, passenger side the starter must be removed. The plugs are brass and they corrode which makes them quite difficult to remove, especially if they get rounded off. Use your judgement, it's not mandatory to remove them.