Changing coolants question

[Zonaman]

I'm getting ready to install my ac system next week and (since the old heater core goes) thought that would be a good time to switch from Dexcool to the green stuff. So starting tomorrow I was going to drain and flush the radiator, fill it up with water, drive around with the heat on, then drain and flush again-run a few erands or drive to work, and repeat till there's only clear water coming out. There's certainly no danger of freezing here in Phoenix but I just wanted to check with you guys. Since the water pump gets some lubrication from the coolant, would a hundred miles or so of mostly water in the radiator damage it or anything else?

Thanks in advance.

[Fred T]

It shouldn't.

What I do to flush is disconnect the lower hose at the radiator, the disconnect the heater hose at the intake. Then I take a garden hose without the male end and clamp it to the intake fitting. Put a shutoff valve in the hose near the truck, and turn on low until clean water comes out both the heater and radiator hoses. Then put the hose end in the radiator top to clean out the radiator. Disconnect the upper radiator hose at the thermostat and you will drain out all of the coolant.

Then hook it back up and fill with water and put in a can of flush. This should get the crud out of the radiator from the dexcool. Flush again and you should be ready to go.

[Fred T]

Forgot to mention that the reason for keeping the water pressure low is so you don't blow out the heater core. They are fragile on these trucks.

[4x4Poet]

Drain the coolant thru the fittings on the bottom sides of the block. If you change the heater core (and drain the rad–Doh!), draining the block also will get 90-95% of the old coolant out. A few fluid oz will remain in the water pump and near a pint will remain in the bottom of the rad below the drain petcock's level that is not true bottom. Pull the rad, water pump, and heater core with a drained block (thru said fittings) and you'll get 99% of the old coolant out. If you don't want to pull the rad, lift the truck in front on the pass side to tilt rad towards the petcock. Helps a little.

[68LSS1]

Do what Fred T suggested. Or just get one of those tees that allows you to attach the garden hose to the heater hose. You don't want to mix those coolants. Driving around with just water won't hurt anything for awhile. But it won't get all the other coolant out. I just reread your post. That would work just make sure it's all out. If your worried about the pump you could put some "Water Wetter" in (that's all I plan on running).

[mrein3]

When you are all done flushing with water there will still be some water in the system. DO NOT fill with 50-50. Look up the capacity of your system and put 1/2 that capacity of pure antifreeze in the system first. Top it off with water and you are good to go.

This procedure is of course assuming that you run 50/50 down there. If you guys run a different mixture adjust for that mixture always adding the pure antifreeze first to account for the water remaining in the block.

[LUV2XCLR8]

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