Need Instructions for Coolent Change / Flush
Thread Starter
Burning Brakes
Joined: Apr 1999
Posts: 1,029
Likes: 15
From: Houston TX
Need Instructions for Coolent Change / Flush
Kind of a dumb question but does anyone have coolent drain / flush instructions for the C5? I really want to make sure the block / radiator / heater core / etc. are thoroughly flushed out when I do this so what's the best approach to take? I dont want to just drain and refill. I'd rather take my time and flush everything out but am unsure if filling the system a few times with water and re-draining will hurt anything (flash corrosion like the brake rotors get after a wash). How do I get the coolent out so the system is completely dry and I can start from scratch? Can I run the car for a minute in the drain process to pump out the coolent from the block and heater core? I really don't trust the monkeys at the dealership to do it right. Anyone with pics or tips I would appreciate your post. By the way, what is the total cooling system capacity including heater core, etc. Thanks again!!
[Modified by Z51 LS1, 8:55 AM 10/4/2001]
[Modified by Z51 LS1, 8:55 AM 10/4/2001]
Burning Brakes
Joined: Aug 2000
Posts: 1,132
Likes: 1
From: Morganton, NC, USA
Re: Need Instructions for Coolent Change / Flush (Z51 LS1)
My 2k is too new for a flush and drain, but I suspect the block and cooling system are similar to other GM carts, so here is what I've done before and what I plan to do in a couple years with my C5. When you open up the petcock, all you do is drain the radiator. I've read that any drain plugs in the block are inexcessible. Get one of those Prestone heater hose Tees, and either splice it into the highest heater hose or use 2 short temporary hoses. Connect a garden hose, run the engine, and soon you will purge all the old coolant out. You can purge, add SuperFlush, then purge again. What I do next is jam a funnel into the Tee and pour condensed or distilled water into the system and hope it purges the city water. Drain the radiator one last time(with pure water remaining in the block) and fill with Antifreeze. Drain the overflow tank and fill this with the rest of the Antifreeze required for the specified mixture ratio. After several runs, you'll start picking up the 100% Antifreeze from the overflow mixing it into the system. Tip: pull one of the throttle body coolant hoses and watch the water come out as you pour in the Antifreeze so you can get more in the radiator. 
