Talisman51

Ok...splitting the fine hairs now.

I understand there are a few issues when replacing C2 freeze plugs. Todays plugs are imprinted with size and in some cases logos, while originals were unmarked. Most today use brass plugs due to their superior longevity; while originals were steel and I am told todays steel replacements are cheesy and will prematurely leak. Lastly, originals are deeper, roughly 1/2 deep vs replacements that are 3/8? deep.

So...here goes...

1. Is there a functional dissimilar metals issue with using brass given the C2's aluminum radiator and supply tanks?

2. If using brass and patching in the stampings, will std. filler putties hold up to rigors of high engine heat?

3. Is there a source for deep brass plugs?

4. Who today supplies the best repro steel plugs?

5. Is this much ado about nothing....is there a NCRS deduct for replacement plugs?

Thanks..

JohnZ

Pioneer has plugs with no logos, but it's hardly a "big deal" - the only plugs visible in judging are the two below the water pump legs (with a mirror), and a logo would only be a one-point deduction.

MikeM

Will paint stick to the brass plugs? Paint doesn't like to stick to a brazed body joint.

Talisman51

John, can ya give some details on the Pioneer product?....brass/steel? depth? size markings?...

Thanks

Talisman51

I have read somewhere that they should be blasted. I suppose roughing them up with some sandpaper would do.

I am more concerned about the dissimilar metal issue with the aluminum and brass causing corrosion.

vark_wso

"Galvanic series" tables list metals according to their potential difference in an aqueous environment when in contact with each other. Brass (yellow/cartridge) is slightly more noble (cathodic) than the gray iron engine block. This is exactly what is desired -- the less noble (anodic -- where corrosion occurs) material have considerably more mass than the cathodic fixture.

If you keep the antifreeze mixture fresh and clean, the pH should be between 8 & 9 or so. As the inhibitors are depleted with use, that pH fall toward the 7, and oxidation of the glychol can occur. Only then is the "aqueous environment" is conducive to corrosion.

I'm not sure what your reference to the aluminum radiator and expansion tank has to do with the freeze plugs, since they are not in contact with each other. Perhaps you're refering to a brass drain **** on an aluminum radiator. If so, once again, this is a very satifactory combination with the more active metal (Al) having the much larger surface area than the more noble metal (Cu). Just don't try that in reverse -- for instance, with a copper/brass radiator and an aluminum drain fitting and old antifreeze with low pH. That would be a bad thing!

Talisman51

Thanks Jeff... You certainly are a qualified source on the topic. Maybe you can tell me why GM went to such lengths as changing the rivet material of the expansion tank cap to match the radiator material? In my cursory research on galvanic corrosion, I read that the materials need not physically touch but must be in electrically connected forming an anode/cathode electrical flow. Given the conductivity of glycol I though this would be the case.

Thanks...