Electrolysis???

[Duk]

Alrighty, I've got some cooling fluid aspects of my project needing some help.
Now I know that aluminium, steel and coolant (water) flow equals electrolysis and that the only way to keep the aluminium from being eaten (short of a sacrificial anode) is to keep it electrically isolated from the steel.

What I need to know is, will (painted) mild steel be eaten by electrolysis if a stainless steel part that has coolant flowing through it, is directly bolted to it?

[agent86]

Hi Duk,
           Radiator and other parts are prone to electrolisis by stray electrical current, this is a fairly common problem and causes premature failure of radiators and components. If you have a decent multi meter or can borrow one you may be able to track down the cause. An auto electrician can generally track down the problem area.
Cheers
agent 86

[colcol]

Make sure your engine has a good earth, otherwise the currents will zap around the cooling system looking for a good earth to grab hold of, and use the right type of coolant, for motor racing you need no [slippery] glycol in the coolant, [usually it is green], with approved for Motor Sport on the label, the late model Alfa Coolants are red, [but are not approved for Motor Racing], Colin.

[Duk]

Cheers guys, but the radiator isn't the concern.
I want to mount a stainless steel hose mount/transition piece (it will have a barbed fitting on 1 side for the original heater hose and use an AN fitting and braided nylon hose that then goes back to the radiator) that will have coolant flowing through it, directly to the body.

[Beatle]

Just do it Duk!  Plenty of vehicle cooling sytems are a mixture of aluminium alloys, steels, brass/copper, etc etc and they last decades if a good and correct coolant is used, and serviced regularly.  As the others have stated, stray electrical currents are more likely to cause damage.

At least this modified item sounds as though it will be relatively visible, so you can keep an eye on it for corrosion, unlike the engine internals where steel-meets-aluminium (liner/block. waterpump, etc).

Where anything mounts to the body, I use a thicker lanoline spray or other anti-corrosion product (tectyl, fishoil, dielectric grease, wax).  The paint will help, but it's not always a reliable insulator, so something which remains flexible and 'self-healing' is the go.  Goopy products help insulate, but also exclude air.