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Just because your coolant looks good and has good freeze and boil protection does not mean your cats cooling system is safe. As time goes by the PH of the coolant drops. As this happens electrolysis starts to take place. Over time damage to the cooling system will result. Aluminum parts are the first to go, Tstat housings are very common. Coolant PH test strips are available but they are not cheap and their shelf life is short. Another method of determining when coolant should be replaced is measuring the voltage across the coolant and ground. I would guess most cat owners have a DMM.

With the engine cool remove the radiator cap. Set the DMM to DC voltage (lowest range if not an auto ranging meter) then place the positive probe on the negative battery post and the negative prob in the coolant. The negative prob should not touch the radiator or you will not get accurate reading. The voltage should be under .3 volts DC if not replace the coolant using a 50/50 mix of quality coolant and distilled water. I find in most cases once the coolant is changed the voltage will be well under .1 volts DC. I'd be interested in everyone's results so please report back.

Other thoughts: Its getting harder to find conventional coolant as the extended life stuff has taken over. As far as I have been told the extended life stuff does not protect aluminum as well as the old stuff did. Even if this were not the case coolant that is not green in color looks out of place in these old cars. It also seems that much of the coolant is premix 50/50 so your paying near the same price and getting half water. I changed the coolant in my 67 standard a few weeks ago and had a **** of a time finding conventional coolant that was full strength. Fleet Farm has diesel rated coolant but its low silicate formula is really not good for cars. I gave up after hitting several parts stores with no luck and used bulk coolant from my work.

Bill
 

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Good post Bill, thanks!
 

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I agree - just like wiper blades - they are finding yert another area to drive up profits by making it "easy" for us to change coolant. The newer stuff does tend to go acidic faster? I use the test strips that change color but the meter test is interesting. Funny thing is I just changed my trucks out this AM! BUt I still have the old stuff in a bucket so I'll see if it shows a diff just for testing. (I prolly only gort about 70% of it out of there though)
 

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My cars are mixed at roughly 25% coolant (basic Prestone) and 75% water nowadays once I add a pint of No-Rosin which says you could run 100% with it and be covered for corrosion.
 

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Bill, With the positive probe on the negative post and your negative probe on the coolant, I wouldn't thing there would be voltage involved. Are you not really checking the resistance of continuity?
 

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Discussion Starter #6
Bill, With the positive probe on the negative post and your negative probe on the coolant, I wouldn't thing there would be voltage involved. Are you not really checking the resistance of continuity?
Test if for yourself. As the coolant PH drops a battery is created. The lower the PH the higher the voltage. Aluminum is one of the plates, Intake, Tstat housing etc. I would guess cast iron or the radiator and heater core are the other plates but I'm not 100% sure. The battery made by the cooling system does not have the same polarity as the vehicles electrical system so the coolant is negative and the negative battery post is positive.
 

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Other thoughts: Its getting harder to find conventional coolant as the extended life stuff has taken over. As far as I have been told the extended life stuff does not protect aluminum as well as the old stuff did. Even if this were not the case coolant that is not green in color looks out of place in these old cars. It also seems that much of the coolant is premix 50/50 so your paying near the same price and getting half water. I changed the coolant in my 67 standard a few weeks ago and had a **** of a time finding conventional coolant that was full strength. Fleet Farm has diesel rated coolant but its low silicate formula is really not good for cars. I gave up after hitting several parts stores with no luck and used bulk coolant from my work.

Bill


I don't know much about the coolant for gas cars but i know that green coolant breaks down the hoses and causes leaks in the diesels. At the shop i work at we build high performance diesel trucks and we only use orange coolant. We had really poor results with the green and I don't know what they did differently between the two but that's just what i've learned/seen.
 

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Discussion Starter #8
I don't know much about the coolant for gas cars but i know that green coolant breaks down the hoses and causes leaks in the diesels. At the shop i work at we build high performance diesel trucks and we only use orange coolant. We had really poor results with the green and I don't know what they did differently between the two but that's just what i've learned/seen.
Orange, so your using GM Dex-cool? Some good info on wikipedia about Antifreeze here http://en.wikipedia.org/wiki/Antifreeze
I'm not a Dex-cool fan as it seems to attack plastic in newer vehicles. Other long life stuff (aka G05) like most other manufactures use seems OK in this regard. Trouble is its not green, usually red, gold or clear.

Bill
 

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Yes it most certainly is time to change the coolant in my cat. Shame on the previous owner for letting it even get to this point. I'll be replacing it in the next few days, probably tomorrow.

 

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Discussion Starter #10 (Edited)
Nice, muddy water. FYI that style tester is the least accurate type I have ever seen. Best cheap tester IMO
http://www.amazon.com/Thexton-106-Cold-Chek-Professional-Anti-Freeze/dp/B0002SRDF0/ref=sr_1_4?s=automotive&ie=UTF8&qid=1322456663&sr=1-4 Best testers are refractometers,
http://www.amazon.com/Robinair-75240-Coolant-Battery-Refractometer/dp/B000HTNODE/ref=sr_1_1?s=automotive&ie=UTF8&qid=1322457065&sr=1-1 I payed close to $70 bucks for mine, looks like the same exact thing. Other cool stuff for doing cooling system service is this funnel set. Its one of my favorite tools. No more spilled coolant!
http://www.ebay.com/itm/Lisle-Spill-Free-Coolant-Funnel-Plastic-Yellow-Kit-24610-/370562188852?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item56473a4634

Yes it most certainly is time to change the coolant in my cat. Shame on the previous owner for letting it even get to this point. I'll be replacing it in the next few days, probably tomorrow.

http://rover.ebay.com/rover/1/711-53200-19255-0/1?type=3&campid=5336714558&toolid=10001&mpre=http%3A%2F%2Fwww.ebay.com%2Fitm%2FLisle-Spill-Free-Coolant-Funnel-Plastic-Yellow-Kit-24610-%2F370562188852%3Fpt%3DMotors_Car_Truck_Parts_Accessories%26vxp%3Dmtr%26hash%3Ditem56473a4634
 
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