Aluminum Radiator Myth or Fact

[TC]

Ok this is the deal, I was talking with some friends of mine that just bought aluminum radiators for their cars and they where telling me that you can't run brass freeze plugs in the motor because it will cause the aluminum to corrode. Now my friend that works at Ron Davis(same place my buddies got their radiators at) did tell me on my aluminum radiators that I shouldn't have any brass fittings screwed in the radiator for the same reasons stated above. But I thought this was only because the brass and the aluminum where touching. But can it really be possible that just having brass exposed to the coolant cause the same corrosion as having a brass fitting screwed into the aluminum. I'm thinking BS. But what do you guys know or think.

[TheSilverBuick]

Re: Aluminum Radiator Myth or Fact

I call bS too. Aluminum water pumps and brass radiators have been working together for decades. Anti-corrosion additives help keep electrolysis corrosion at bay.

[squirrel]

Re: Aluminum Radiator Myth or Fact

Aluminum intakes and brass freeze plugs and radiators have been working together for even longer...and flathead ford aluminum heads were around in the 30s....

[Freiburger]

Re: Aluminum Radiator Myth or Fact

I never thought about that, but it does create a potential for electrochemical corrosion due to electrolysis (different metals between water acting as a conductor. Same reason that aluminum body lifts on Jeeps tend to eat the body tub. I think that aluminum has more negative charge than the brass, so it's likely that the aluminum will be the material that get eaten (it's the anode, the brass is the cathode). We've all seen intakes killed badly around a steel water neck on boat motors: same problem, but aggravated by salt water. But whether electrolysis is active enough to be relevant in a cooling system is a different question. Dunno.

[CTX-SLPR]

Re: Aluminum Radiator Myth or Fact

Brass and Aluminum in direct contact in a wet environment will cause galvanic corrosion. Aluminum is on the Active end of the table, Brass is in the middle towards the Noble end. It'll corrode the aluminum in any case but if you ground all of it it should be minimized and shouldn't really happen on a brass plug aluminum radiator combo.

[Freiburger]

Re: Aluminum Radiator Myth or Fact

How do you ground all of it? Are the bolts holding the radiator to the core support good enough?

[CTX-SLPR]

Re: Aluminum Radiator Myth or Fact

Sorry about the short and somewhat confusing reply, was on the phone doing wedding planning stuff with my fiance.

There shouldn't be a grounding path through the coolant to the brass plugs in the block for the radiator. Best way to ground the radiator is the same as grounding anything else, either bolt it directly to something that is grounded or run an external grounding wire. Most radiators I've used are set in rubber saddles so they don't actually contact the steel frame or coresupport. Aluminum also creates a marginally conductive stable oxide layer that makes it hard to get good grounding just by physical contact of things resting on one another. Unless you have a serious, like over 0.75V between your coolant and your ground, I'd not worry about stuff on the engine since its not in direct contact and your coolant should have reached a buffer system state with the stuff in it vs eating the parts its contained by. As for direct contact stuff... its going to be so slow you'll never notice it unless you have some sort of accelerating potential across the interface such as it grounding through the hardlines to the transmission or something.
To give an example from work, in our ultrasonic inspection tank we had a turntable that was made out of stainless steel, the tank was also made of out stainless steel. The two where not grounded to one another and there was a huge (for this kind of thing) 1.5V potential between them and underneith 2 of the legs of the turntable it had eaten about 0.020in into the stainless steel tank bottom. simply wiring a jumper between the turntable and the tank reduced the potential to around 25mV.

[Freiburger]

Re: Aluminum Radiator Myth or Fact

Thanks for the info.

This is more important than your wedding. Get your priorities straight, man.

[KeithTurk]

Re: Aluminum Radiator Myth or Fact

TC I'm calling BS too... Anti corrosive antifreeze's are common today... My scooters call for it up front... as does every modern car...

So what the hell... do what you do... let the idiots that know it all do what they do.... Life is Good...

Keith

[clutch]

Re: Aluminum Radiator Myth or Fact

I run Evans waterless coolant best way to control electrolysis on your expensive aluminum race parts. also runs cooler to ;D

[DanStokes]

Re: Aluminum Radiator Myth or Fact

If you have concerns, you can do what we do with water brake dynos. Screw in a GROUNDED magnesium plug and let it sacrifice itself to save the engine parts. The ones for Clayton water brakes are about 2 1/2 inches long and have a 1/2" NPT pipe plug - I think the SuperFlows are similar. If it self sacrifices, you'll know that you have voltage in there.

Dan

[CTX-SLPR]

Re: Aluminum Radiator Myth or Fact

Zinc is a better sacrificial annode than magnesium but it can cause dealloying in some metals. We used it in our tanks but it caused the stainless steel to start leaching something in the general area, I'm guessing its the titanium in the alloy but we weren't going to cut a section out to run it in the SEM. Boy do I miss that job... now I have a desk, 8 people working for me, and lots of excel spreadsheets to work on. I guess thats what being promoted does to you, right DF?

[Freiburger]

Re: Aluminum Radiator Myth or Fact

Yes. The corporate ladder only leads to a jumping platform.

[Saltfever]

Re: Aluminum Radiator Myth or Fact

(snip . . ) caused the stainless steel to start leaching something in the general area, I'm guessing its the titanium in the alloy but we weren't going to cut a section out to run it in the SEM.

What does the SEM do for you except show some pitting or possible interstitial effects? Wouldn't gas chromatography or x-ray dispersive spectroscopy be a better diagnostic tool?

[JeffMcKC]

Re: Aluminum Radiator Myth or Fact

Evans waterless does not work on a high pressure system, at Ford we have a issue with this on the popular Taurus, just run a wire under a hose and ground it. If you want to know if its happening, use a test strip from the parts store, or stick a volt meter in the coolant and ground it. Myself I never leave a motor in long enough for it to be a problem. :