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Old 06-06-2006, 03:00 PM
540IA_750IL 540IA_750IL is offline
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Location: usa
Join Date: Jun 2006
Posts: 17
Mein Auto: 750IL
Cool Solution to Exploding radiators.


Did you ever wonder why some BMWs have exploding radiator, exploding overflow tank, bursting hose, heater core leak, problems. Well here you go:

BMW decided to run the system at 30PSI, that is a lot of pressure, your tires are probably at about 35PSI. Sure the radiator used in BMW is not the best, but not that much worse than Lexus, or any other car. Pressurize any toyota or honda to 30PSI drive it hard and see how long your radiator will last.

The system pressure is controlled by the overflow tank cap ($ 15.00 item), open your hood on top of the cap you will notice 200 this means 2.0Bar or 30PSI. Change this cap to the one used in 1988 325 (140 rated at 1.4Bar or 20PSI) it should fit most BMWs with plastic caps and now you have less pressure and smaller chance of exploding radiator. Now that your radiator has smaller chance of exploding you have a greater chance of water boiling (but I take that over exploded radiator, boiling water all over the street, plumes of white smoke, other drivers lughing, me stranded, any time)

BMWs cooling system appears to be too small for hot climates, you need a radiator with more cooling area (like two or three rows of cooling fins), or more free space under the hood, or bigger water pump+more air flow (2 electric fans).

Toyota and Lexus are closer to 15PSI, most american cars and trucks run at 16PSI but I like BMWs.

My 1991 750IL would blow up 1 cheep aftermarket radiator each summer, one summer I got sick of this Cr&% and started to butcher the original cooling system. I anstalled a aftermarket tranny cooler aprox $100.00 at and all aluminum chevy style radiator $159.00 at JEGS 16PSI radiator cap and all metal hoses by coolmaster $90.00 also at JEGS now I am on my third summer 110degrees Chicago + stuck in traffic+ air running full speed and mu BMW is nice and cool.

I just purchased a 2000 540IA and I will try the lower PSI cap trick before I go for the chevy radiator and cap.

For what its worth
this is my 2 cents.
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