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Old 01-08-2007, 09:46 PM
n pinson n pinson is offline
BMW 750iL
Location: Champaign,IL
Join Date: Feb 2006
Posts: 338
Mein Auto: 750il
E38 radiator/expansion tank replacement

This is not a DIY article but just some encouragement for those that are wary of doing this yourself.

My rework on the cooling system was finished on Friday afternoon.

It is a 1996 750iL and had 52,xxx miles on it when we got it. It now has 67,xxx miles on it.
Unfortunately, BMW designed the cooling system with a lot of plastic parts and after 10 years the plastic was as brittle as glass.

It all started this summer when me and my father were going way too fast in it on our way to town. The upper radiator hose fitting on the radiator itself partially broke and caused the upper radiator hose to come off. As a result we lost a huge amount of coolant. Well I didnt want to mess with the radiator and just put the hose back on the now shorter stub coming out of the radiator. It all worked great but one day it did come off again because it wasnt in the right place or tight enough.

Well everything worked great for about 3 months. I didnt think about it that much, but always worried that it would cause me grief again. Well one day I was heading over to have lunch with my girlfriend, and when I was leavin this guy was standing beside the car and said that he just saw a puff of smoke come out of the hood and and there was a puddle of coolant underneath the car. This is when the expansion tank went. It had a huge crack about 4 inches long on the back side of the expansion tank.

I ordered a new expansion tank thru the local dealer and with very little trouble replaced it.
However this is were I made the another huge mistake by not buying a new radiator and replacing it as well. But I put it off again.

Well, it finally failed for the last time on New Year's eve. It developed a massive crack right underneath the upper hose outlet and was leaking huge amounts of coolant. Well I was about 9 miles from my house and decided to try to limp home. So i stopped by a gas station and bought 3 gallons of water. I had to stop every couple of miles and fill it up with another gallon or so. I went thru all 3 gallons on my way home.

Well I went and bought a new radiator from Auto Parts Warehouse...very good place. In about 2 hours I pulled out the expansion tank that I had replaced earlier, drained the bad radiator, pulled it out, and installed the new one and put all the parts back in their proper place.

Now I spent about 2 hours installing the expansion tank the first time and about that same amount of time replacing the entire radiator and expansion tank the 2nd time. It is really a very easy project if you use just a little common sense....and dont lose any of the small parts. I am only 16 years old and i had my 15 year old brother help me the 2nd time so he could learn something from it but I had no problems that come to mind. It looks very professional now, especially after I cleaned up the coolant stains inside the engine compartment. I recommend doing this project if you have an E38, regardless of mileage. The plastic in the system simply breaks after a while and I speak from experience, it sucks sitting beside the road in a car with a problem that could have been avoided. Ill take some pics of the engine sometime. Anyways, if anybody has a questions they would like to ask feel free. This has been done by a number of people already and there are plenty of DIY articles for the 740i/il guys out there as well. This is simply advice, please dont take this as something you have to do or your car will have the same probs as mine, I just know from reading other articles that this is a reoccuring problem. Best of luck

HERE IS A GREAT DIY ARTICLE FOR THE 750iL E38 for 1999 year plus but still very helpful. http://www.csit.parkland.edu/~npinso...eplacement.pdf

Last edited by n pinson; 01-08-2007 at 09:57 PM.

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