Questions about radiator/engine flush and running water or coolant

[Houston Ben]

Hi all,
After messing with my new intake for a/c and such I realized I hadn't changed over to coolant yet so I have a few questions.

!. Can I run just tap water? This is what I have been running and seems to work and cool fine.

2. If NO to #1, what is the best method to flush the radiator and engine of all the brown water without using harsh chemicals or taking it somewhere?

Any other words of wisdom?

Thanks!

[Xeen]

To flush the cooling system of most impurities I would use the slow water change out method.
Open up the radiator drain valve all the way.
Open the fill cap.
Let the radiator drain until empty then close the valve and refill with water.
Replace the fill cap.
Start the engine and let run until normal operating temps are reached then shut off and let cool for 10 min.
Drain the radiator again, then refill with water.
Start the engine and let run until normal operating temps are reached then shut off and let cool for 10 min.
Drain the radiator again, then refill with water.
Start the engine and let run until normal operating temps are reached then shut off and let cool for 10 min.
You get the idea here, do this 5 times.
Then drain the radiator one last time and add 100% coolant, read the container and make sure it is not the 50/50 water/coolant mix.

DO NOT open the radiator drain valve and put the hose in the radiator and fill with fresh water and just let the engine run or you may blow a head gasket.
Patience is the key here you don't need to get in a hurry and risk damaging your engine.

[truckdude239]

You should never run tap water.... there are chemicals in that will erode the inside of cooling system. Destilled water or coolant. Remenber coolant has a higher boiling point.... and a quite lower freezing point

[Clyde65]

Originally Posted by truckdude239

You should never run tap water.... there are chemicals in that will erode the inside of cooling system. Destilled water or coolant. Remenber coolant has a higher boiling point.... and a quite lower freezing point

If your only ! I mean only trying to flush it out, then tap water should be fine, HOWEVER as TruckDude said, never use tap water for cooling your engine, especially one with aluminum heads.

The LSX engines hold air if emptied, so you should jack it up in the front when filling for final time AND fill the engine first with your coolant\distilled water mixture.

[corndoggydogg]

I just performed a full flush on my system using one of those Preston flush kits. It worked well and a lot of gunk came out. However, I just realized that there is still a bunch of water (I figure 2 gallons) sitting in the engine block that won't come out. So after adding the 50/50 mixture, I figure the true effective mixture is now only 75% water/25& antifreeze. I tested the liquid and it is not giving me any freezing protection.

My original thought was to reflush the system, and this time, remove the coolant plugs on the engine to fully drain the system. Then refill with 50/50 again. But...I can't get the plugs out.

Reading through this thread (and now doing some reough math), it sound like the best (and easiest) course of action is flush, drain as much as I can though the radiator, and refill with 100% antifreeze.

Does that sound like a good plan? This is my first time doing this to this truck. I just purchased it and have a feeling it has been neglected for many years. So I really want to do the right thing here and return her to all her deserved glory.

Also, does anyone recommend replacing the t-stat at the same time as this flush? Just a thought.

Any feedback would be greatly appreciated.

Thanks!

[Andy4639]

My suggestion is to take the old thermostat out and replace after you have gotten all the old water and gunk out.
To get almost all of it out jack the rear of the truck up high enough so when you take the hose off the water pump it will drain almost every drop of water out of the block. Have the thermostat out of it when you do this.

[BigDan3131]

Another way to help remove the water is to use air pressure to force the water out, just don't go crazy on the pressure.