Posted by PeteL on January 30, 01 at 15:54:30:
I cut/pasted this off the Corvetteforum. Some interesting material. It is edited for total posts, but not within any single post. I could not maintain the poster names becasue of the UBB board type - this information available. The voltage information is of particular interest to me, as this is what I have been working on for a couple of months (I do believe there is a voltage developed that can be helpful in determining usefullness of the coolant - may also be cross referenced to Ph.) I have e-mailed Texaco and asked for testing insight regarding the Dexcool product and will post the details of any responce I may (or may not) receive. Comments appreciated.
Quote begins:
OPEN,
I read that the Dexcool contains NO silicates and as a result waterpump life is increased. Having said that, I've read on the forum that some have experienced low mileage pump failure.
I have 151K miles on a Z-28 which still has the original pump (of course the pump is a different design than the C5).
I use the following method for determining the time to replace the coolant. I posted this back in August, but maybe it won't hurt to show it again, for newer members.
Subject: Re: Electrolysis.....
Here are the notes for checking the condition of your coolant,
based on the voltage drop between the coolant and ground. As I
recall, the Neg. probe goes into the solution and the Pos.
probe goes to ground. It doesn't matter as long as you're
using a digital VOM. Disregard the neg. sign in front of the
reading. The absolute value is all we're interested in. If
you want the reading to be positive, just reverse the
leads if the reading is negative.
In summary.....place one probe into the coolant at the
radiator neck...don't let it touch any part of the metal of
the radiator. Ground the other probe to the neg batt
terminal and take your reading. Do the test with the
coolant warm, engine off.
FINALLY....WHAT THE READING MEANS.......
.2 v or 200 mv.....to .5 v or 500 mv...........acceptable
.5 v or 500 mv.....to .7 v or 700 mv..........borderline
.7v or 700 mv......or greater...........unacceptable.
Hope this helps.
Mark
Pete,
Maybe some of the chemistry buffs can help out here, but I think those voltages give an indirect indication of the hydrogen ion concentration in the coolant, hence some idea of the electrolysis activity.
I originally obtained the information in some automotive newsletter that I used to receive.
The Z-28 that I mentioned in the above post had a factory fill of Dex-Cool and the pump seals have held up better than in any car that I have owned.
Where did your bud come up with his meter info?
Mark
As a side note, any truck dealer, ie Mack, has coolant test strips, essentially ph testers. Pick some up, hell, they might even just give you a few. Package of 50 cost around 5 dollars. They work on either green or red stuff.
I'm not sure if the test strips that test reserve alkyliniy are valid with Dexool because of the different corrosion inhibitor technology, but nearly all the HD diesel engines manfacturers (Cummins, Cat, Detroit) are using a similar blend for factory fill. The HD version includes an additional additive to address the wet liner cavitation erosion issue with diesels, and they use test strips for this particular additive, so be sure you understand what test strips will test and what blends they will give a useful/valid result.
The voltage test has been around for a long time. Not sure if it is valid with Dexcool, but I have never read anything over 300 millivolts in any of my cars, which have all had Dexcool since 1995.
Duke
There are more reasons than a consumer is told about Dexcool, first, Havoline makes dexcool for GM, second, it will not help you to add Dexcool to a system already using the conventional green coolant, as this will contaminate the Dexcool, and you will loose some of its corrosion inhibiting properties.
Here is why, The inhibitor package within Dexcool chemically bond to metal in a different way than the green coolant. This is the reason for the great corrosion characteristics. However, the green bonds to the metal, and is ABSORBED into the aluminum of the heads, block and whatever. Therefore, no matter how many times you flush a green cooling system, it will not allow the Dexcool to bond correctly to the metal, therefore, contaminating the Dex, however, it will still give better seal life, just you will still have to change it for the corrosion protection.
Hope this helps, Best to ya, c4c5
Hey there c4c5specialist.
I also have a 1996 Impala SS . The 1st year the General put Dex in.
You may be aware of our "No Heat " Issue as this also is affecting other product lines.
To be brief, the infamous "Brown gel/sludge" is present in the overflow box. Squeezing the hoses makes it work for a few months. I see some design flaws for the cooling system on the Impala as well. This is a 35K car, original owner,maintained.
To this day Gm is pointing it's finger at Havoline, Havoline at GM. No leak tablets from the factory??
I want the dealer to fix it under warranty.
Do you have any inside info on what is causing our no heat situations ??
Thanks ,
Steve
There is a TSB on Dexcool. It was applicable to the 4.3 liter V-6 light truck engine. GM blames the sludging problem on running an excessively low coolant level for extended periods. There are a number of anecdotal reports on Dexcool causing problems on other engines. I can't figure it out. Don't have the TSB number handy, but talk to your service manager. I think it was written in early 1999.
P.S. Found the number: 99-06-02-012, 28 May 1999
Duke
Totally agree with Chuck, a good dealer can make all the difference. As for the Dexcool contamination problem, basically here is how it goes. When you mix antifreeze, you are supposed to use a distilled water to combine the 2. I know of very few people who actually do this. The sludge was due to water treatment problems not taking all the minerals out at the factory before the mixing of the water and the Dex.
I have tried to use a bunch of different test methods from TAN, our technical help, with no avail. The voltage check is truly the best way that I have seen, but on newer vehicles, if you want to flush it, just combine a 50 50 mix with distilled water. It is cheap insurance, and I havent seen one with the sludge problem yet, YET.
I really dont know if it is a chemical problem at Texaco, but this is all that I can tell you. Am going to GM training today, so I will ask if there is any more info.
Best to ya, c4c5
Thanks for the info. guys.
That confirms the research I have already done on the Distilled water & early Dex issues. Just wanted to make sure I haven't missed anything!!!!!
The dealer is good, but is is always better to to go armed with research & facts that not.
Steve
Quote ends