OK I've read all the previous posts includin the factory service procedures... However one thing still remains unclear to me. Since we can't easily dump the coolant plugs on the engine block, Ill be doing the drain, fill with water, run the motor, drain, fill with water, run the motor till the water is clear procedure. But, once you are done this and it is clear water, how exactly do you know how much dex-cool to add in to get the right concentration as certainly there will be residual clear water left over???

 

As I recall, I looked at the capicty of the system and added 50% of that amount as Coolant. The rest distilled water.
Hope that helps.

 

:iagree:

 

Unless you definitely need to flush the system (i.e. gel or crud in the system) just drain and refill with premixed (mix it yourself 50/50) Dexcool and distilled water.
That way you introduce no city water or guessing game.
I've done a lot of reading on Dexcool failures and they are all traced back to contaminated or overdiluted coolant.

If you insist on flushing you can have the mix tested by a dealer. FYI - you can mix Dexcool between 50/50 and 70/30 Dexcool/water.


[Modified by Bugster57, 7:21 PM 7/7/2003]

 

I did mine today and followed the service manual for my '98. I drained out the old which was 5 years old and it looked clear and clean not dirty at all.

I then refilled with tap water (the manual calls for clean drinkable water) and ran the engine to warmup letting the thermostat open up. I then drained it out and repeated 3 times. BTW I also turned on the heater and ran it at max temp to make sure that the heater core got flushed. After the 3rd time the water was clear.

I bought 6 gallons of distilled water at Walmart. I refilled with distilled water for the final rinse. :D

After I drained it I added 4 qts (one jug) of dexcool. I then added another 2.5 qts of dexcool and filled the rest with distilled water. I ran it and let everything flow and mix. I'll check it again in the morning.

The manual calls out a capacity of 12.3 quarts (A4) so a 50/50 mix would be a little over 6 quarts. I figure that I'm slightly over 50/50. BTW I have a 160 degree thermostat so I only needed to run the engine up to around 180 degrees

 

What do you guys do with all that old fluid durnig this flushing process?

 

I made a simple adapter for flushing the C5. It is 6 inches of 2" dia. radiator hose that is slipped onto the threads of the overflow tank and secured with a hose clamp. The other end has a pvc adapter hose clamped also. To this I attach a garden hose and run water through with the engine running until the liquid coming out the drain is clear. I restict the water flow until the temperature gage indicates the thermostat is open and also run the heater. I try to purge the city water by pouring 4 to 6 gallons of distilled water through the adapter with the top fitting removed. This applys a small amount of head to the system. Since draining the radiator removes about 6 1/4 quarts, I figure there is another 6 1/4 quarts in the engine, hoses, etc. because the total coolant volume is around 12 1/2 quarts. Since the desired coolant mix ratio is around 50-50, I simply add 6 1/4 quarts to the radiator and overflow tank. After a few trips, the pure antifreeze should mix with the pure water giving the desired mixture. :cheers:

 

OK this is what i wound up doin.... i emptied out the radiator and then filled it up with water. Then I turned on the car, shut the rad cap and waited for the temps to raise up. Then I opened the drain cap and under pressure the water blew out the radiator drain fitting. Shut the drain, filled it back up and repeated the process 3 more times. I used a white 5 gallon bucket and noticed that even the final 'flush"still didnt get the water completely clear. I suppose i coulda kept goin but I noticed the water started boilin at around 212 F so that means that the coolant had had enough removed that it no longer extended the boiling point.

I then drained the radiator and I took 2 gallons (8 qts) of Prestone Dexcool and tossed it in, and topped it off with tap water. I figure the capacity was 12.9 quarts on the MN6. 8 quarts of antifreeze is approx 62% antifreeze to water, so that would put it within the 50-70% antifreeze combination called for.

Now I have to drive the anti-freeze to the local recycling center, since I"m enviromentally conscious :)

I kinda screwed up with the water combination so I probbly have mostly distilled water and a tiny bit of tap water. Oh well. It wasnt too bad, it was just a little tedious having to heat up the car etc.

Next project... flush the brakes and flush the clutch..