Re-filling Coolant Questions 96 k1500 5.7L

Draining just the radiator does not drain the entire coolant system. There is still coolant going through the engine block and lines. I've always heard a drain and fill replaces around 40% of the coolant in the system, so it's about right that you are only using 7 quarts.

What can you do at this time? Did the truck still have Dexcool when you started? Did you switch to the green coolant? If so, get to some place that does a flush (hooks up to a machine and sucks out the old while putting in the new). Do this very soon as Dexcool and green coolant don't mix! Do a google search in this group for some examples. If you are staying with Dexcool, or you have all ready switched to the green and are doing it again, run the truck for a couple days, then do the drain again. Run the truck a few more days, then do it again. Mathmatically speaking, this will get most of the old fluid out by the third time (35% + 35% +35% = 105%).

HTH Enjoy Bill

96 Chevy K1500 Z71 91 Audi 200 TQ

sorry, bill, but your math is off.

if you remove 35% of the coolant for each drain/fill, then you will do just that each time. You will dillute in, only. Technically, you won't ever get all the old stuff out. You'll never get to a total flush, unless you flush the whole system.

Regards, Snowman

Thanks for the help to this point, folks.

I drained the coolant before I did the intake manifold gasket replacement, but I did not drop lower coolant hose from the motor. Refilled radiator with water hose to test engine (didn't take note of how much water went back in). After completing the I.M. Gskt replacement, I figured that I should get it back to "specs" as much as possible by changing back to Dexcool. Drained coolant per manual instructions - again. Refilled w/ Dex + H2O in 50/50 mix (approx).

The manual mentions a coolant drain petcock in the block somewhare, but I couldn't find it.

I replaced the water pump in summer 2002.

I am 100% certain there was nothing left in the any of the ports when the I.M went back on.

BTW - the BCS sucks.

Chris

Can't you just monitor the overflow tank and add coolant to it if you find that is't getting low. I could be wrong, but every time the engine warms up and cools down, doesn't the coolant get pulled back into the engine until all air is out and the engine is full of coolant. My 4.3 does this, granted the rad opening and over flow fill tube are the highest points in the system. Don't know it that makes a difference or if your setup is similar.

I never flush with garden hose anymore. I just drained the rad and overflow tank. Fill with new coolant. Drive for a week and repeat. Sometimes 3 times. Obvoiusly not I'm getting all the old coolant out but the system is diluted enough with new coolant that the pH is within an acceptable range which is all i'm concerned with.

Rob, Good suggestion; I didn't think about that (duuhhh). I think that's what I'll do.

Thanks, Chris

There are drain plugs on the block, one by the oil filter and the other at the Knock sensor. About

10% still remains. So a good flush is needed, the add straight Antifreeze as required for 50/50 mix and top off with water. Allways a PITA.

Cheers

"Chevguy" wrote

Sure it will. But you are better off not to rely on this method without topping up the coolant cold first.

Ian

Snowman,

You're absolutely right, that's why I said "mathmatically speaking". Granted, mathmatically speaking, an egg never hits the floor if you drop it, and a super ball never stops bouncing once it starts, so there is a huge flaw in that theory.