Hi co-members,
FWIW
5 Year Dex Cool change time.
1) Two GM Gallons Dex Cool bought
2) 8 Gallons Distilled Water Bought

A) Engine Cold
B) Jack up passenger corner a few inches, did not remove wheel/ tire.
C) Placed catch can under rad. to drain by loosing (should not need a tool) rad. drain plug, which I did not remove.
D) Aprox. two gallons Dex Cool drained.
E​​​​​​) Removed Coolant Reservoir (Two hoses - pliers need, Two nuts - 10 mm). Raise res. to expose second hose retainer clip once nuts removed.
F) Inserted crushed ice and shaked to clean interior of res. (thanks Marta Stewart for ice trick)
G) Re-install res.
H) Add 1.5 gallons water....slow pour to reduce air bubble issues.
I) Start Engine, do not install res. cap, idle for 4 minutes, monitor coolant reserve water level, add the next .5 gal over time, raise rpm to 2.2K for 2 minutes.
J) Re-drain radiator, loosen drain plug again (Noting each drain got out two gallons of fluid).
K) I found 3 water flushes brought a clean/ clear system, yet watch out during that third flush as the water boiled out the res., that did not happen during the first two flushes.
L) After the final flush remove the rad drain plug, inspect, lube o-ring with new Dex Cool reinstall hand tight.

System hold 12.6 quarts.
Once flush, add 6 qts Dex Cool, and water to res fill line.
I found squeezing the radiator hose helps remove air bubbles, still a slow pour.
Drive car, let cool and refill with water to fill line.
That should do it.
I don't think I left out any steps.
Could be considered a messy job for all you with carpeted garages.
Total time, maybe 4 or 5 hours, but done right and with distilled water

Have fun.

 

So close, but you missed a step on an older C6.
Hence pull the heater core lines, so you can back flush all the crap that can get trapping in it, out of it with the flow of water through it backwards.

On the aluminum engines, the heater core flushing only yields a little bit of debris, but on the older steel block motors, you would not believe the amount of crap you back flush out, even with the motor being a few years old.
Hell, on the older Jeeps since you pretty much keep the heater cranked to max heat dam near until summer (due to the soft top/lack of the car holding heat in the cabin with the steel block motors), you would swear that your getting gravel out of the heater core on a back flush with the size of chunks you would get out of of the heater core.

 

Dano's expertise is so welcomed by me.

Yes older, 2005, C6.
Factory manual did not indicate Dano's advise, at least the section I was reading.

So.....
Start the car, turn on the heater, get up to operating temperature, turn off car, remove coolant reservoir cap.
Then, remove the heater hoses at the firewall (two of them?) and let gravity do its thing?

Can't wait to see the mess this will make

 

You kind of do the heater core back flush right after you finish the distilled water flushing and it drained.

To do it now, remove all the dexcool so you don't loose it or clamp off the heat line hoses), do a quick water flush to get the last of Dex cool out so your not blowing it all over the engine/shop, then pull the heater coil hoses to back flush the heater coil.
Myself, will go back flush, normal direction, back flush, normal direction, then final back flush with a water hose and tap water, to work any solid crap that may be in the coils, out of the coils and core.



As for old dexcool/raditor fluid, not a bad idea to hang onto it, if you have pumps like power washers and such that you need to winterize. Hence pump saver, and winterizing solution is just Glycol, and is the same stuff that is used in winterizing solutions as well. Just run the old stuff through a strainer to get the solids out, and it ready to be used for winterizing your pumps over the winter so the water in them, does not freeze.

 

I must be doing something wrong as I am only getting approximately 1.25 gallons to drain when I do the process above. I have flushed a few times and still only have approximately 1.25 gallons drain out. Temps get to 195 when reving to 2500 for 2 min after the 4 min at idle.

What could I be doing wrong? Is there air in the system?

 

Thank you all for the info.

 

Use a shop vacuum in reverse and blow air into reservoir when emptying the coolant. That will help you evacuate another half gallon, about 2 gallons altogether.

 

I also always remove the thermostat during the flush. I'll use it again if it is less than 10 years old otherwise I'll replace it.

 

Thank you. I got another 1/2 gallon with the shop vac. Still only 1.75 gallons drained. I am doing this with a single jack on the passenger side front. Maybe if the car was flat I would get the last 1/4? Or maybe my gallon jugs of water are a little oversized.

 

I haven’t done this on my Corvette but I have on other cars. Open the drain valve to a good steady trickle, and leave the coolant cap off so you can add a similar good trickle from a house water hose. Turn heat to highest temp. Let that continue until the trickle coming out is clear and after the car is warm and the thermostat is open of course. Keep an eye on the thermostat but a steady state isn’t hard to maintain and you can always stop the process. When clear, drain and add straight coolant for 50/50 mix. Any reason it would not work on a Corvette?

 

Thats the problem. The drain has to be the lowest point. Lower the jack as much as possible. Or lift the back of the car somehow.

 

check this out... venturi vac for refilling coolant specifically...

https://smile.amazon.com/OEMTOOLS-24...2241910&sr=8-3

 

Thank you but that also requires compressed air which i do not have. I use amazon spill proof funnel( $16) works like a charm, at first try every time. It gets rid of all trapped air.

 

Which Amazon funnel do you use? I see several with an Amazon search.
I am having the same issue with only one gallon gravity drained.

 

It is the one made by epauto. It is orange spill proof funnel kit. Sku QQ-01A-1#JJ01