Radiator leak

Got a 2002 530i that has a hairline crack at top of radiator approx. 2 inches in front of outlet. What type of material is it(plastic, poly stuff,) or what ? Will a good epoxy repair it ? If so , what type ?

The radiator has plastic tops and tanks, with aluminum cores. You should *NOT* attempt to repair it. Replace it - it's only a couple hundred. You should replace the expansion tank at the same time. If they fail, you have 10 seconds to get to the side of the road and turn it off before you're completely empty and start damaging the engine. Don't risk it.

The radiator and other cooling components on modern BMWs are notorious for failures; most people replace them pre-emptively sometime between 60K and 120K.

X2! Don't mess with that! Replace it ... unless you don't mind walking back from wherever you drive.

I disagree on the expansion tank. Of course, I've never seen one do anything other than turn yellow with age.

C.R.,
The expansion tanks on E39s & E46s are less "passive" than they are on our E28 & E30 jalopies. They are mounted next to the radiator and undergo a much tougher heat cycle/life than ours mounted up & out of the way. If you're going through the drill and replacing the radiator and coolant, do you the car a favor and replace the expansion tank as well. It's not too expensive, compared to the potential repair cost after a failure and resultant overheating.

++ There are pics on bimmerforums of failed expansion tanks, if you really want to search them out. You basically have to remove the radiator to get to it anyway, so why not replace it at the same time. FYI, the independent that works on my cars says they've seen more expansion-tank failures than radiators.

E46 Expansion Tank

In July of this year I replaced my leaking Expansion Tank along with the Water Pump, Belts and Hoses. Radiator will be done this winter. Have to save some more money first.
bluewagon

The cost is not as bad as you might think

Both Turner Motorsports and autohausaz.com have excellent prices on cooling system parts. Turner even offers complete kits, which is nice. Check 'em out, you really need to get a new radiator at the very least.

Cheers

Don't risk your car or your safety.

Replace the radiator and overflow tank.

It is cheap plastic and needs to be replaced. Best bet is to do it now before you have a catastrophic failure. The E39 cooling system operates under great pressure and blow-outs at speed can result in total coolant loss risking permanent engine damage. If you have any more than 80k miles you are at risk and ought to plan on replacing the entire cooling system that is radiator, expansion tank, water pump, thermostat, and all hoses. Alternatives are few - Zionsville sells an all aluminum radiator which does not share the same inherent short comings as the OEM plastic products. Another alternative is to replace your traditional water based coolant with a product from Evans called NPG+ because it is not water based and because of this runs at a far lower pressure which reduces the strain on the cheap plastic OEM parts.

http://www.zionsvilleautosport.com/

http://www.evanscooling.com/npg/

Ummm, if they're "cheap plastic OEM parts", why do we complain about replacing them? They're cheap, remember?

Evans sells a high concentration ethylene glycol/propylene glycol/water mix (according to their MSD sheet). You can make your own for a lot less than $30/gallon.

For the record I see your MSDS is dated 2003 and does not indicate how much water is in the product. A more recent MSDS for the product dated 3/24/09 says that it is less than .1% water. I think you can see this is far less than your 50:50 mix of BMW coolant & water.

http://www.hrpworld.com/client_images/ecommerce/client_39/products/pdf_3415_3.pdf

And yes, cheap in this context means inexpensive and crappy, low quality materials that have no place in such a key component as a cooling system that operates at high pressure if it is filled with a 50:50 mix of water and BMW coolant.

Something can be cheap in terms of quality and still cost a lot of money. Although BMW radiators really are not that expensive when compared to other manufactures.

With the increasing number of problems with the plastic radiators, BMW dropped the price of them by ~50% about 6-8 years ago, and considers them a "consumable" these days.

I guess it's easier than actually fixing the problem

THIS ^^^. You are not helping yourself by attempting to repair, you will save yourself a lot of time and you will save your engine by just replacing the radiator.

Here's what cheap, crappy plastic looks like up close and personal.

http://www.bimmerfest.com/forums/showthread.php?t=428099