Electrolysis in the Cooling System

[peterkehoe]

Hi Folks,

I've got an N15 Pulsar (GA15 engine) here with an electrolysis issue in the cooling system. It was quite corroded when i got it recently, the chump I bought it from had run it on tap water for a while (he actually told me coolant was a scam to squeeze money out of suckers! ) . Anyway I've flushed it thoroughly, then ran some evaporust in the system for a few days then flushed and back flushed the engine, rad, and heater core thoroughly until there was no more debris and the water was clear.

I've filled it all back up with coolant now. I decided to check for rogue voltages and electrolysis in the system. I've read a few things online which mention this. One thing they all mention to check for is voltage in between the battery and the coolant. I've read a few places which mention a few limits for this voltage some as low as 50mV but the majority of sources seem to say that 300mV is the upper limit.

I've just checked mine and its around 400mV. So I'm trying to work out what is causing this voltage and figure out a way to get rid of it. I've checked the obvious grounds around the engine bay. They seem to have good connections. I'm in the process of cleaning the contacts on them at the moment anyway. I'm far far from an electrical person so I'm flying by the seat of my pants a little.

Do you guys have any ideas of places to look for the source of this voltage or ways to get rid of it?

If the block is steel but the radiator and heater are aluminium, wouldn't this automatically form a galvanic cell anyway and produce electrolysis and voltage?

Is there any easy fixes to this? If I just add a new ground to the radiator maybe? I've heard of anti electrolysis radiator caps, are these any good?

Thanks a lot guys!

Best,
Peter

[B13_Red]

I would exercise caution on adding "grounds" (paths to negative battery terminal), as it invites other dc current paths, which may have a corrosive result. Clean-up the existing grounds. Hopefully the manufacturers have done their homework in that respect (ground paths and corrosion mitigation).

[peterkehoe]

Thanks for the reply. Interestingly, after 24hrs the voltage I'm picking up has now dropped to about 150mV. I'll keep monitoring it for a while and see if it drops further. Maybe there is a little charge generated when the coolant is changed, or by the flowing water in the flush process.

I've a couple more grounds to check on. I also suspect the previous owner may have messed up speaker installations in te front doors. I'll check that out too and make sure the wires aren't causing an unintentional charge to the system.