Do yourself a favor. Pop off the radiator cap. Drag out your multi meter, stick that black lead on a good ground point, and dip the red lead in the coolant at the radiator neck. Don't touch the radiator itself, just the coolant.
I'm guessing you'll see a few volts. If you do, your radiator is probably not far behind. It's being eaten.
Time for a good flush, replace radiator, and make sure the radiator and the heater core are well grounded. Don't assume they are grounded just because they are mounted. I did this recently on my van to cure the same kind of problem. Ran a ground lead right from the radiator itself to the main ground point where the battery grounds to the body. No more voltage in the radiator neck.
Finally got around to trying this out, mainly because I think I just blew the radiator [which is new by less than 6 months].
So as a scientist extraordinaire, I filled the missing gallon of coolant into my radiator and was waiting for the foam to die down and I thought, maybe I should check for voltage within the coolant like MarcusOReallyus said.
I had a notion that I wasn't going to find much, if anything, but I did it anyway.
Here are my results:
1st reading no contact 0 volts
2nd reading front battery while running only: 14.78 volts. Not bad!
3rd reading, negative prob connected to negative of front battery, positive lead dipped into moving coolant, not touching any metal, just coolant>> 0.26 volts.
Interesting.
But to go further, as the temperature was rising, the voltage was progressively higher, but always under 0.5 volts.
For those that may be wondering, WTF are you doing? Marcus brought up a valid point and it is usually overlooked, ground straps, like this one below:
A corroded, broken or missing ground strap can cause all sorts of issues electrically, but can have an adverse affect on your cooling system as well.
The reason? Electrolysis. EDIT>>>So all in all, if you have a few volts going through your cooling system, you most likely have a ground path problem (forgot to add that last night).
The electrical system needs a path to ground back to the battery, think of the battery and a circuit as a hula-hoop, when a positive lead goes out to feed a load (like a lightbulb) a negative lead needs to come back to the battery. The most vehicles, the chassis and engine are parts of that path, this is why there is a negative lead coming off the battery and fastened to the chassis. But wait, it doesn't end there. You have the chassis grounded, now you need to provide a path from the engine to the chassis. Ground straps/cables. If the ground path is narrowed by missing or corroded ground straps, then the coolant can act as a makeshift electrolyte to carry the return ground back to battery, but at the same time causing electrolysis. The electrolysis can eat up metal parts and cause unsuspecting leaks or parts failures. Not just the cooling system but other parts like shifter cables and such, just using the cooling system as a example since I am having trouble with it in my 1009.
The engine is not typically grounded to the chassis. Think about it. The engine mounts are rubber, that insulates it from the frame mounts, same with the tranny mount and the rear and front axles. The body is insulated with rubber body mounts also, so you really do need those irritating ground straps more so than you think.
I have said this in another thread before, the path to ground must be equal to or greater than the positive lead for everything to work properly. Not in just one wire, but all the wires collectively, if you get my meaning.
Anyway, sorry to bore you guys with this sort of techno mumbo nonsense, but I had to share. That and it gives me a reason to sit down and enjoy my nice cold frosty adult beverage.
Do apologize for the thread being so long....
)
