Tester
I think I understand the āhowā of the voltmeter test, but I donāt understand the āwhyā. Why is the voltage difference from the battery ground to the coolant a measure of coolant condition?
Lets see if I got this. You just put new coolant in your vehicle . There are no air bubbles , the vehicle does not over heat or leak fluid. So who cares about voltage ?
Iām just going to leave this link here for your perusal.
http://asecertificationtraining.com/testing-for-galvanic-activity-and-electrolysis/
A voltage in your coolant indicates and exchange of metallic ions between different metals used in your engine, i.e. it is eating up parts of our engine. There will always be some voltage due to galvanic corrosion which is two dissimilar metals (I.e. iron, aluminum) in contact with an electrolyte (coolant or water). The higher the voltage, the more damage is being done.
If current from an external source is introduced, such as a bad ground, then the process is sped up.
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@keith do u have the link for your sources?
Most are on Youtube. Some are training videos for mechanics, some are amateurs. Most of this is new to me. @Testerās first link got me started.
I plan on doing the coolant changes in the Camry and Subaru and repeating the tests right after. For all I know right now, 150-200mV may be the norm for coolant until it is almost depleted, but the coolant in both vehicles is going on 6.5 years and the Subaru is over on mileage according to maintenance and warranty booklet in the glove box.
Iām going to clean up the grounds in the Silverado and see if that makes any difference. I should one that the Silverado has been leaking coolant through the head gasket recently, about a half gallon a month but I put in some of that Subaru Conditioner and the leak has stopped. Maybe the residual exhaust gasses in the coolant have thrown off the pH. I donāt really know right now.
If I find my pH tester, Iāll use it to see where I really stand, but right now I know the acceptable range but I donāt know the nominal or ideal pH.
2013 Mazda5 with 100k uses FL22 type coolant. 2 yrs ago dealer mistakenly removed the coolant hose - so he had to top it off.
So I measured the voltage before starting the car - car was not driven for days.
Voltage initial = -0.06volt (note it was minus voltage - coolant was negative relative to ground)
Voltage at 2000 rpm = 0.00 volt - almost Ground.
So what do I make up out of this? Is this test conclusive?
Should I now do the pH to finish off the testing process?
Personally, I plan on getting some litmus paper from a drug store and test mine, just havenāt done it yet.
I was doing a little more research limiting myself to the coolant manufacturers, Prestone was the only site that had anything on testing. They had a link to a video of a guy doing the voltage test. He was getting 0.3 volts (300mV). The coolant was so bad it was already a muddy brown. That sort of makes me wonder about the validity of the voltage test, especially with 400mV as a limit.
I normally donāt like dredging up old posts, but I do have an update on this. I never got any litmus paper but I did find one of my pH testers. I tested some coolants. First new concentrated Subaru coolant, pH 7.8.
Used Subaru coolant - 100k miles, pH 7.2. New Toyota premix, pH 7.2. Did not have the used Toyota coolant with about 100k on it.
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Good info, proves the coolant becomes more acidic w/miles. But in the cases you measured, not much.
Thanks - after posting it, I ended up in changing the coolant myself. Already 100k. Hereafter, I should change every 5yr/60k. I have concentrated coolant leftover - will the leftover go bad during the 5yr shelf life period?
I did not spend the money on litmus paper - just changed it with OEM coolant.
Will do the Spark around 120k or 110k - Scotty also recommends to change the Spark even if it appears good to reduce the load on the starter motor.
The main thing in coolant that gets used up is the corrosion inhibitors. No metal in the jug so the antifreeze stays fresh.
Smart move on the plugs, but not for the reason that Scottie says. You have to understand inductive reactance, which is a semester course all by itself so needless to say, Iām not going there in this post. But trust me, if the plug misfires, it will damage the coil. Old fashioned coils were oil filled and the oil is self repairing, modern epoxy coils are not self repairing so any damage is permanent. Your starter motor will survive but the coils, not so much.
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@keith, so what mileage (interval) one should change the Iridium plugs?
It depends, there are two types of Iridium plugs. Both have Iridium center conductor tips, but one type has just a regular iron ground lug. It needs to be changed at 50-60k miles. The Iridium tip lasts forever but the ground lug erodes away.
The more common type these days has a platinum disc on the ground lug. The platinum disk is very resistant to erosion and the plug is good for 100-120k, at least. You would be safe to replace these at 120k to insure trouble free operation.
None of the above applies if you start to burn a lot of oil. No plug is resistant to oil fouling.
Use the exact brand and size spark plugs that are OEM.
As to when to change plugs, follow the owners manual.
Strain on the starterānon-sense. My previous car plug change per owners manual:100,000 miles, I delayed until 106,000 miles, absolutely no change in starting or MPG.
This isnāt the sixties where you could experiment with different brands and heat ranges.
Thanks @keith
I believe it currently has the one that came from factory - 107k mileage. I will change it around 120k then.
I donāt have any oil burn or leaks - interior looks like new - it was mostly freeway car - now became commuter for my partner as the other was totaled!
Once mpg dropped - likely due to lack of usage. Now regular driver, city mpg is almost 25mpg.