How to Flush Engine Coolant w/o Starting Engine
 

After rebuilding the top end of my 5.3L, I'm pretty sure I got all sorts of gunk into the water jackets of the block. Is there a good way to flush these out without starting the engine? I don't want this stuff going through the water pump, radiator, or any of the other cooling system.

I was thinking of installing the water pump and and filling the block with water through the water neck, then draining the block using the two 8mm allen plugs under the block, and doing this a couple times. Or maybe just running the water hose with these plugs open? But I'm not sure if that will clean out the water jackets in the rear of the enigne (I don't know the coolant flow off the top of my head).

Or my third option was to just get a hose and shoot water down the water jackets with the heads off (the heads are still off at this time). Seems like this would be the most effective way, but could get water in the cylinders.

Ideas?

Even if you could flush it without running the motor it would still go through the pump on it's way out... Go somewhere with a pressure flush and have them fix you up it'll be fine

Take the water pump off and flush it that way...

Remove the hoses and water pump.. rig up a water hose and let it run for a few minutes, then back flush it. Keep swapping it back and forth for a lil while.
Thats what we do anway.

If I'm putting water in through the neck on the water pump, doesn't the flow split between the two banks, travel through the water jackets, then out the drain plugs?

On the drivers side bottom of the motor there is a large brass plug that threads into the block. You will need a 17mm allen socket to remove it. This will allow you drain the engine block.

This is the method I used on my LT1, on more than one occassion.

x2

it works. Its a little time consuming, and a PITA if you are draining into a pan, and not on the ground, but it works.

Rig up a pulley on the end of your drill and mount your drill on top of the engine so that the pulley lines up with the water pump. Put a belt on the pulleys and run the drill to turn the water pump...this works better with an air drill :jest:

Just kidding, but spinning the water pump would work. (with the return hose disconnected while filling through the rad)

Nonnie's back flush method works, but I don't like putting non distilled water in my engine...I'd do it on a customer's car though :jest:

I also like to drain the engine block like MrGoodwrench mentioned, when just draining and fillng...this is what I'd do on my own engine.

Or you can take the engine out and turn it over and lay it on it's face :jest:

Sorry, I wasn't a lot of help :D

I just ended up hosing water directly into the water jackets with the heads off and the plugs out. I'll do another flush as soon as I get the e-fans working.