Kurt G.

I recently replaced the aluminum radiator in my 65' roadster with a new correct Tom DeWitt aluminum radiator. A friend told me that I should get a radiator cap with a "sacrificial anode" attached to help ward off corrosion and help extend the life of the radiator. Has anyone used one of these ? Or does anyone have any input as to thier effectiveness?? As always, Thanks for the help. :confused:

RGGregory

I don't see a sacraficial anode (I assume zinc) being of any great help with corrosion protection in an aluminum radiator. I don't know what alloy Tom uses for his radiator (I have one of his in my 67 327/350), but if you look at a galvanic series/chart, you'll see that zinc and aluminum have nearly the same electrochemical potentials. Even different heat treatments of the same aluminum alloy have different galvanic potential...For example, if I remember correctly from MIL-STD-899Z, 2014-T4 aluminum is about #10 on list (starting with the most anodic), while 2014-T3 is around #25 or so on the list. And zinc is just a little more anodic than aluminium, so it would preferential corrode if those two metals are electrochemically coupled. However, aluminum forms an aluminum oxide passivication layer that stops corrosion (or greatly reduces it) after a small amount has occurred.

I'd say pass on it, and just maintain your coolant and radiator well.

We use zincs a lot in submarines and surface combatants for corrosion prevention, but that is with the use of a lot of steel alloys (and nickel-copper as well as nickel-copper-aluminum, which are seawater corrosion resistant).




[Modified by RGGregory, 1:43 AM 3/29/2004]

Kurt G.

Thanks very much for taking the time for the informative response. I think I'll just take good care of the radiator & coolant and not worry about it. I want to maximize the life of this radiator because they cost so much !!

Thanks again. :steering:

SWCDuke

There is a specific AC radiator cap that should be used on models equipped with aluminum radiator and remote aluminum expansion tank - RC-26. This is a 15 psi cap that is also the service replacment for earlier aluminum radiator/expansion tank systems with 13 psi caps.

It is constructed to be galvanically compatible with the aluminum expansion tank, and use of other caps may cause corrosion.

Duke

RGGregory

Duke,

I really didn't think corrosion would be a problem, though I guess if was something noble compared to AL, you'd have a problem...am I forgetting my corrosion engineering?

Bob

SWCDuke

I don't recall all the specific whys and wherefores. The Chevrolet Parts Catalog is very specific about using the RC-26 on models with aluminum radiators/expansion tanks. I believe it's okay to use the RC-26 on brass radiators, but the normal brass radiator service cap should NOT be used on an
aluminum expansion tank. Joe Lucia has posted all the gory details on the NCRS DB, and he is rarely off the mark.

My recommendation would be to only use the RC-26 cap on aluminum expansion tanks.

Duke

SWCDuke

The RC-26 is called out as the service replacment cap for all 60-67 w/aluminum radiator.

Duke

Kurt G.

Thanks to all for the discussion and suggestions ! As usual, my question is answered in record time.....I appreciate it. :cheers: :seeya :steering: :auto: