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tettes 02-07-2013 12:05 PM

Second coolant leak in 8 months
Guys, back in May I had a coolant leak in my 2003 540i that i thought was fixed. Parts replaced include:

Expansion tank
Fan clutch
Radiator hoses

I got the 'Check coolant level' warning light today, and I opened the hood and saw the dreaded white splatter.

My question is: Should the work that was done have prevented this from happening? Or is it possible that I didn't get everything overhauled, which lead to another leak?

I want to be fully informed when I go back to the shop so he doesn't try to sell me parts I don't need. If any of his parts failed, they are still under warranty.

Any ideas?


acoste 02-07-2013 12:37 PM


Originally Posted by tettes (Post 7366211)
Should the work that was done have prevented this from happening?

Depends what's leaking now.


Originally Posted by tettes (Post 7366211)
Or is it possible that I didn't get everything overhauled, which lead to another leak?

Just because you didn't replace something won't cause other parts to fail. But when removing and installing the coolant hoses from/onto plastic parts will stress that piece of old plastic. So it is possible to have a crack shortly after the overhaul but not months later.

Expansion tank failure is very common even if it was recently replaced. Search this site for the best source of exp tank.

tettes 02-07-2013 12:39 PM

Good info, thanks, acoste. I'll take the car into the shop tomorrow and see what they say.

Any other bits of knowledge that could help?

Thanks again!

crazy4trains 02-07-2013 12:51 PM

Water pump and radiator are other likely sources, among others too numerous to list. I recommend you look at cn90's cooling links and consider anything that has coolant flowing through it as a potential source.

Good luck and please report back!!!

mbell666 02-07-2013 02:45 PM

If it was a Behr OEM Expansion tank, 8 months is right on time for failure. Easy check is, when fully cold, to stick your hand under the expansion tank and feel for coolant.

The Behr ones have been made in China very badly, I had two fail both ~8 months. The fix is have a genuine BMW one fitted, if your shop deals with a few 540i they will have had this issue already.

champaign777 02-07-2013 03:05 PM

every time i see "coolant leak" i run to check my
please no more posts like this .. :eek:

AnotherGeezer 02-07-2013 03:09 PM


SFbay 02-07-2013 03:12 PM

Don't forget 105C!!!!
Any small air in the system will increase pressure!!
Bleed it well

Nline6 02-07-2013 03:28 PM

Suprised you didnt replace the radiator while you were replacing the other things. I bet there is a "micro" leak or crack in the radiator. All depends on where the white spots are coming from.

16valex 02-07-2013 04:24 PM


Originally Posted by champaign777 (Post 7366640)
every time i see "coolant leak" i run to check my
please no more posts like this .. :eek:

Your is not V8 why worry?:eeps:

tettes 02-25-2013 08:04 PM

I'll find out if they used the Behr version tomorrow when I pick the car up. As it stands, they replaced the expansion tank under the warranty, thank goodness.

Will report back.

Burning2nd 02-26-2013 12:48 AM

I had a great run.. I got 15 month between my last leak and this one...
BUt my behr tank failed...

seeping right thur the side... I went with a BWM one this time... see if there's any better quality

These cars have a lot of plastic in the cooling systems... It happens... you have to stay on top of it... If you want a car that will run 100k with out problems... get a honda :)

Wish i had a warranty On my self... so i could contact (Me) and have my self replace my tank at no cost

tettes 02-28-2013 11:57 AM

i just picked up the car and the shop told me it originally used the behr tank, but this time used the oem tank.

burning - yeah, i did a lot of research on the e39 on this site before bought it, so i pretty much knew what i was getting myself into. i'll be curious to see how long yours lasts...

thanks, all!

Burning2nd 02-28-2013 01:20 PM

Msg me so i have you in my inbox... and when this one... (the 2nd) fails ill let you know... Im installing it tomarrow

SFbay 03-01-2013 09:50 AM

You need lower temp tstat and it'll last like honda;)
Get 95C

Burning2nd 03-02-2013 06:10 PM

Brass for the win

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