Did Coolant Flush Today

CapitalTruck · July 9, 2009

Did a coolant flush today and put in a new thermostat (major thanks to ms3dale for giving me the right part numbers for the stat and seal). It took me quite some time to get the old coolant out (like 5 or 6 drain and refills). Didn't want to screw around with the block drains, scared they might leak.

Found it interesting that my shop manual and the owners manual had different capacities for the system (GM Shop manual said 13.x quarts, owners manual said 15. I added 7.5 quarts of Dex-Cool based on the 15 quart spec)

Question, does Dex-Cool respond to specific gravity (protection) tests like traditional ethylene glycol?

Matt_ · July 9, 2009

Question, does Dex-Cool respond to specific gravity (protection) tests like traditional ethylene glycol?

Yes, you can use that 'bulb' tester. Dex-Cool is actually ethylene glycol based. (it's SG is only like .01 different then traditional antifreeze... well within the resolution of the gauge)

However, I still recommend using the test strips to test Dex. It's great coolant, unless the PH gets out of range... so keep an eye on both and you'll be set

superjim · July 9, 2009

Question, does Dex-Cool respond to specific gravity (protection) tests like traditional ethylene glycol?

Yes, you can use that 'bulb' tester. Dex-Cool is actually ethylene glycol based. (it's SG is only like .01 different then traditional antifreeze... well within the resolution of the gauge)

However, I still recommend using the test strips to test Dex. It's great coolant, unless the PH gets out of range... so keep an eye on both and you'll be set

What is the "CORRECT" Ph values for DexCool?

Matt_ · July 9, 2009

Don't remember off the top of my head.... Its been a while.

I always used the voltmeter test to check it.... I never trusted those test strips, if they sit on a shelf too long they can give false readings

jhm · July 9, 2009

Question, does Dex-Cool respond to specific gravity (protection) tests like traditional ethylene glycol?

Yes, you can use that 'bulb' tester. Dex-Cool is actually ethylene glycol based. (it's SG is only like .01 different then traditional antifreeze... well within the resolution of the gauge)

However, I still recommend using the test strips to test Dex. It's great coolant, unless the PH gets out of range... so keep an eye on both and you'll be set

What is the "CORRECT" Ph values for DexCool?

8.3

cujo8 · July 9, 2009

I was not aware of the pH spec for the DEX cool antifreeze and I think if they had a pH spec it would be in the form of an acceptable pH range rather than a single ph value of 8.3. So when the pH value goes out of spec does it usually drift down into the acidic pH range? When the pH falls outside of the spec range what problems does it cause with the cooling system? I assume the only fix for this is a coolant flush and fill, correct. Thanks.

Just for curiosity sake I think I will check the pH of my engines coolant and compare it to fresh mix of 50:50 dex-cool/water at work and see how they compare.

jhm · July 9, 2009

I was not aware of the pH spec for the DEX cool antifreeze and I think if they had a pH spec it would be in the form of an acceptable pH range rather than a single ph value of 8.3. So when the pH value goes out of spec does it usually drift down into the acidic pH range? When the pH falls outside of the spec range what problems does it cause with the cooling system? I assume the only fix for this is a coolant flush and fill, correct. Thanks.

Just for curiosity sake I think I will check the pH of my engines coolant and compare it to fresh mix of 50:50 dex-cool/water at work and see how they compare.

[/quote

Right, 8.3 is the nominal value. I should have stated 8.0-8.6 is acceptable.

Matt_ · July 9, 2009

Yea if the ph goes down to 7, change it ASAP.

If you have a voltmeter, put the negative probe on the negative battery terminal and the positive probe in the coolant. If you're reading 0.2 to 0.5 volts, you're good. Anything higher than 0.5 should be changed.