Help with Radiator Stray Current ?

[vs ute III]

Wondering if anyone can help. My 99 VS V8 auto ute split a side tank. Bought a new radiator and fitted it up on the weekend. Also replaced the thermostat and top and bottom hoses, may as well do the job properly.

Done a full flush and replaced with genuine coolant. Took it back to the radiator man on the monday for him to check for stray current in the coolant. It was reading 0.07 volts which is too high. He suggested cleaning the battery terminals and retesting. I done this ,all good now with a reading of 0.02 volts which is under the allowed maximum of 0.05 Volts. The stray current test is done using the multimeter, negative probe to the neg terminal of battery and positive probe in the coolant with the motor running (the positive is to only touch the coolant , not any part of the radiator)

But here is the problem. Doing the above test i get a reading of 0.02 volts, but if i put the positive probe on the radiator i get a reading of 0.7 volts (nearly 1 full volt ) more than ten times the acceptable level for the fluid in the radiator. I also get the same reading if the motor is not running.

I took it back to the radiator man this morning and he confirmed that the coolant test was ok, when i asked him to check the reading on the actual radiator he didn't, just saying that that would not be a problem.

Can anyone set me straight on this? I am not really up on electric current but this doesn't seem right to me.

I've checked some radiator websites , they all say how to test for stray current but do not mention testing the actual radiator itself.

Thanks guys

[The1]

Have you checked the earth near the battery on the Body itself? Turn each accessory on and off and see what makes it fluctuate, i wouldn't be to worried about it though, your coolant is in the Green.

[woteva]

Can anyone set me straight on this? I am not really up on electric current but this doesn't seem right to me.

Voltage and Current are 2 different things. Voltage is potential difference, so you are only measuring a difference, not actual current flow.
Also the radiator core is not connected to the body directly, it is insulated by the plastic side tanks.

[markovr]

I put a extra wire from the body earth to a metallic part of the radiator...try temporarily fixing a wire from body to the radiator and see if you loose the potential difference(voltage) all they recommend is to use distilled water and the right amount of concentrate(50 per cent) and it should be alright.

[RX25SE]

Only the voltage in the coolant is the issue, and yours is fine.

If you are worried you could run a grounding wire from the metal part of the radiator to the body of the car. This will send the stray current to ground.

Personally I wouldn't bother.

edit: Just read above post!

[vs ute III]

Thanks guys for the help.

wateva, i think i understand what you are saying,but wouldn't the coolant carry the current from the radiator to the block?