Aluminium vs brass/copper radiator

[Billzilla]

Well okay I could be wrong but I would have thought that giving everything zero resistance to everything else eliminates stray currents.

[Madhatr]

so you should insulate these from the bodywork, yes?

like factory alloy rads, because they are typically mounted by plastic end tanks.

i've heard some people say you should fit an earth strap, wouldn't that ask for current flow and encourage electrolysis?

Not an earth strap to the radiator, that will only provide an easy path to ground. Fit a new earth strap to the motor, or fit another one if you have a good existing one. Stray current loves flowing through cooling systems, you want it to be a terrible earth, not a good one otherwise it will simply earth through the radiator.

Ive seen bad earths on motors that resulted in throttle cables becoming the earth point. It will just go where it can, doesnt matter what medium it travels through, as long as its conductive.

[pillow]

Also have a cheap chinese copy, less than half the price of having PWR make one. No problems here, welds and end tanks looked pretty good.

Those welds are a fuckload nicer than my top of the line Aussie desert coolers rad

[RB30-POWER]

so that radiator posted above with the metal brackets welded on would need to be mounted by rubber washer/grommets etc to prevent contact to the body correct?

[Turbo 351]

so that radiator posted above with the metal brackets welded on would need to be mounted by rubber washer/grommets etc to prevent contact to the body correct?

Yes, also to take up any body twist.

[Madhatr]

so that radiator posted above with the metal brackets welded on would need to be mounted by rubber washer/grommets etc to prevent contact to the body correct?

I just used rubber mat to run the length of the brackets welded to it. A couple of bolts hold it in place through body sheet metal, everything was good.

[GTSBoy]

I wouldn't worry about trying to insulate the rad from the body. Just make sure there are big fat earths on the motor that work.

[Madhatr]

I did it more so the fucker didnt vibrate when the fan kicked in :D

[nutwood]

What's the conclusion on earth straps? Normal electrical practice would be to tie everything to earth but I'm thinking that an alloy radiator may suffer more from electrolysis than anything else.
Aluminium's a sacrificial metal and you've got it connected to other metals via an conducting liquid. Instant battery! If half the battery is floating (insulated from earth), battery won't discharge, radiator won't eat out.

[GTSBoy]

Did you read the thread?

[PHULL]

Alloy is lighter, has to be repaired by welding and it won't corrode if you use the right amount of coolant. (They all contain corrosion-inhibitor these days)
Copper is a little heavier but cools slightly better.

Looking at the numbers copper works better than aluminum... problem with copper radiators is the solder used to hold them together has really bad heat transfer properties...

on another note you guys are correct. you still have a more reactive metal ( aluminum in the system. and it will sacrifice its self for the more noble metals. so why not add another metal higher up the scale like a large block of Zinc so as to stop the corrosion for good.....

[BigMuz]

Those welds are a fuckload nicer than my top of the line Aussie desert coolers rad

Have you ever tried the button marked 'Search' on here?

[matty12]

Looking at the numbers copper works better than aluminum... problem with copper radiators is the solder used to hold them together has really bad heat transfer properties...

Also has brass tubes.

[nutwood]

C'mon GTS. Of course I read the thread. Didn't seem to me that there was a real conclusion on earth straps. Discussion up around 14 was relevant but I'd have thought someone would have nailed it with a radiator manufacturers recommendation or something.
I'd reckon if you strapped everything back to earth and tried the multimeter test (Madhatyr #9), you'd get zero volts. Warranty condition satisfied but will the radiator last?
Phull's suggestion of an anode is sound if you could be sure it's in the right place. When you think about it's surprising the manufactures don't fit a couple of zinc or magnesium anodes in the tanks. Perhaps they sell more radiators by not bothering or perhaps electrolysis isn't the problem that it'd appear to be?

[Madhatr]

Dont earth the radiator. Make sure you engine earths are up to the scratch.

Yes. Without electrolysis you wont get corrosion. You need a voltage, however low to react. If you have a zero reading you'll be the first vehicle in history to do so, but your radiator will also last a long time If its created by a supplied voltage you get electrolysis (the biggest problem in cooling systems usually), but if its an electrochemical reaction due to different metals, it generates a voltage too. I dont think you realise how tiny 30-40mV is.

What about the rest of the alloy in the cars guys? heater cores, trans coolers, throttle bodies, extension housings, thermostat housings, water pumps. Shed loads of cheap, thin alloys found elsewhere in the cooling system too, before you even get to the rad.

As already matty12 mentioned briefly above, the inner core and tanks develop a coating or "skin" over the alloy which protects it from corrosion. Its not really corrosion, but rather a reactive process. Its actually alluminium oxide that forms on the outer layer and coats the fresh metal, forming a good insulator to both current and oxygen and protecting the metal below. It's essentially an anodising process, quite a few microns thick, its very tough. Electrolysis is generally responsible for stripping this layer bare, allowing the alloy to corrode. Without the oxide layer the metal has no protection.

People generally consider this taint, say for example, on wheels or the like, but its a naturally occuring process. Next time you pull off a waterpump have a look on the inside, you'll find it coated black/dark grey inside.