what matt is talking about is true.. mainly for these it is the heat/cold expansion of the plastic. i have had to replace mine how ever the newer ones as in 1999+ use a more earth friendly plastic. making it more prone to cracking sooner then what a early 90's would be. my mother has a 2003 330ci just had to replace the expansion tank that matt talks about due to cracking. all the work on her car has been done at the local dealer. i need to check records for when the last time it was replaced.

if you want head over to www.bimmerfest.com , im on there for my 540i. there is a lot of info about that and other things that happen. that is should you need more info beyond the radiators from/for a bmw.

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1976 Plymouth Feather Duster
2002 Dodge Dakota 4.7l v8

You can typically get 100,000 miles out of the radiators, but the plastic gets more brittle as it ages (from both time and heat cycles) and the upper water neck isn't thick enough. Horsepower won't kill them, but frequent enough use will. Mine survived about 150K miles, and that's on the high side from what I've heard from other owners.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Wow that is good service!
Thanks for the report, I will check them out.
Cheers.

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Psychics will soon lead dogs to your body!

1963 Dodge Dart 270 convertible

yea most owners see about 80k out of them before needed to be replaced. there is a all alu rad with no plastic tank from zionville but it cost some money. here is one for the E36 body, not sure if that is the early 90's or not.
http://www.zionsvilleautosport.com/stor ... 6ARIOC.htm

would be nice to see if this one fits my duster for the electric fan, single speed or two speed fan.
http://www.zionsvilleautosport.com/stor ... 89SDCK.htm

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1976 Plymouth Feather Duster
2002 Dodge Dakota 4.7l v8

Out of curiosity.... what are owners of aluminum radiators doing to prevent corrosion? Do most people just let the aluminum oxide take its corse or take a more active approach like anodizing or clear powder coating?

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'66 Dodge Dart

if you mean the bmw owners, just anti-freeze 50/50. almost all of the blocks bmw uses are alu alloy. the only cast iron block i know of is the 3.2l inline 6 making 330hp.

either that or i have you mixed up with mixing metals, ie copper with alu. is that what you meant? if it isnt then im not sure, unless it has to do with the type of alu alloy used.

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1976 Plymouth Feather Duster
2002 Dodge Dakota 4.7l v8

No, my question wasn't about bmws at all... since the discussion is about aluminum radiators for the SL6, I was asking how others have treated their aluminum radiators (if at all) to prevent corrosion.

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'66 Dodge Dart

I just bolted a used 79 /6 Volare unit in my Duster. I had to buy an upper hose for a Volare. I even got the shroud.

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

ok then leave out the part where i said bmw then. read the rest and answer my questions please. i am trying to understand if you are asking about mixed metals in a cooling loop. other wise you might be asking about the rad just sitting bolted to the frame.

i doubt the rad is all alu, alu tubes wouldn't stand up to the high pressure unless really thick walled (could be wrong). more then likely the tubes are brass or copper, then alu finned with expansion tank being alu as well. i dont know unless i contact them about the rads tube construction, i mean in the link i posted.

my 03 dakota has a alu fined rad, there is no sign of any kind of oxidation going on. i have seen some pics of old soda can, ext that are alu. they have no tarnishing at all, we are talking cans from as far back as the 30's.

maybe that helps where i was trying to go with the other post?

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1976 Plymouth Feather Duster
2002 Dodge Dakota 4.7l v8

The '82 Horizon I bought new, suffered a radiator plugged by dis-similar metal corrosion, but I'm told that all brand name anti-freeze mixtures now contain a product to prevent that problem. I'm also told that anti-feeze now needs to be changed more often to retain the anti-corrosion feature. I have no idea if that is correct, but I've never experienced the problem since that '82 model.

The builder of the aluminum radiator I just purchased said to paint the exterior with black engine enamel to keep it from oxidizing.

Bad advice. If you want to paint a radiator, use paint designed for radiators. HERE'S ONE. Any paint will insulate the radiator to some degree, interfering with heat transfer. Radiator paints are formulated to insulate less, and may have a higher emissivity than plain aluminum.

Polishing a radiator also decreases the emissivity, and reduces the heat transfer, so don't do that if your cooling system is on the edge.

If I had an aluminum radiator (and I am seriously considering it), I would not paint it.

Just for grins, here's the Aspen radiator in my Valiant (Edit: Better image):

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

Several years ago, I used a recommended radiator paint on one of my cars and it remained a gooey mess for months. It blackened everything that came in contact with it, so I expressed concern about having that happen again. The insulating issue was also discussed, and for the very reasons you cited, he said to use engine enamel and nothing else.

I have zero expertise and knowledge when it comes to thermal issues, and was only repeating what I was told by the manufacturer.

Some possibilities:

Bad batch of paint. It happens.
Application issue - Bad nozzle, too thick a coat, humid conditions, etc.
Wrong kind of paint. I was referring to paint made specifically for automotive radiators. I see that there are some grill/radiator paints for high-temperature home applications that really aren't right here.

I'm not saying engine enamel won't work or will cause a problem. It is, however, not the best paint for this application.

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

As a mechanic I've seen hundreds of cars, almost all with aluminum radiators- none of them painted or coated. I think only one had a leak at the metal core tubes. 99.9% of the failures I see are from the plastic tanks cracking or the tank to core "gasket" leaking. Unless you live in a "high-salt" area, I wouldn't worry about external corrosion.

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63 Valiant Wagon
225 - 4 bbl

One of my friends brothers brought his 240sx drift car over from Arizona and parked it up in the forest for a couple years and the radiator still looked brand new. I think the housing will outlive the cores getting plugged.

My .02 cents

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Annabelle: 1970 Dodge Dart Hardtop
1991 Nissan 240sx (sileighty) Lots of mods
1974 Dodge Dart *Wrecked*