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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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  #1  
Old 11-19-2012, 05:35 AM
white_lancer white_lancer is offline
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Radiator replacement

Hi I have an BMW E46 2002 320i Saloon. I noticed a water leak from the radiator at the weekend comming from the top at the front of the engine bay. I have located a new radiator on the internet and wondered whether this is a job that I can carry out myself instead of paying a dealer to do it. Has anyone done this job and how difficult is it to do at home?
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  #2  
Old 11-19-2012, 07:46 AM
QAfred QAfred is offline
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It is simple, but make sure you change expansion tank and radiator cap too. Do some research, lots of info on cooling system overhaul.
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  #3  
Old 11-19-2012, 10:21 AM
lgr122 lgr122 is offline
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Replacing parts seem to be easy, but taking coolant out and putting new in right way is bigger issue.

Took me couple hours to get home from garage when needed to stop and cool off/ add coolant/ let air out every once in a while.

So it's good idea to see what else should be replaced in cooling system and do it at the same time.
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  #4  
Old 11-19-2012, 01:36 PM
white_lancer white_lancer is offline
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Quote:
Originally Posted by QAfred View Post
It is simple, but make sure you change expansion tank and radiator cap too. Do some research, lots of info on cooling system overhaul.
why do I need to change expansion tank and radiator cap?
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  #5  
Old 11-19-2012, 03:56 PM
QAfred QAfred is offline
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Because you have to remove the expansion tank to get the radiator out and you would not want to re-install a 10 year old tank after installing a new radiator. They expand at a micro level every time you get the car up to running temp. They have a limited amount of cycles before they crack. Typically they blow every 70 k or so. If it is an automatic you should also change tranny thermostat...#4.
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  #6  
Old 11-20-2012, 02:41 AM
jcjdavis1 jcjdavis1 is offline
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Hi. It is relatively easy job to replace the radiator, I did mine outside the house. I would buy an original radiator as I bought an Ebay one and it fitted but wasn't just right.
Doing the expansion tank is just a precautionary measure as they fail, (mines did). Jim
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  #7  
Old 11-20-2012, 03:25 AM
heztheone heztheone is offline
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probably a silly question, but are u sure that ur radiator is leaking water and not some hose or some other part related to the radiator?
it's very rare (at least to me, never heard of such thing) that a BMW E46 radiator leaks, unless it was damaged. usually most of the times it's some plastic that gets old enough that it cracks due to high heat, or some hose
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  #8  
Old 11-20-2012, 04:01 AM
white_lancer white_lancer is offline
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leak

Not a silly question at all. At first I noticed a "puff" of what looked like steam comming out from under the bonnet. I put some "radweld" in the radiator to see if it would fix the leak. I left the car running for half an hour as directed by the "radweld" and it did seal the leak.

It was only when I drive the car that it started to leak again. I guess it was the additional pressure build up from the system. The leak is right at the top of the radiator in the middle. I am not an expert but I am not aware of any hoses running through this location?

I will try and do some more investigative work and possibly remove the radiator at the weekend to identify exactly where the leak is before I go and purchase a new radiator. In a way I am sort of hoping that it is a leak from something else like a fitting or a pipe as this will be easier to rectify.
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Last edited by white_lancer; 11-20-2012 at 04:02 AM.
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  #9  
Old 11-20-2012, 06:41 AM
lgr122 lgr122 is offline
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Hot tip!

It's good to wipe any extra mess off while you're there.
I didn't... so in the morning i was afraid it still leaks, but apparently all coolant stay inside now... i think...

Ofcourse it's possible that water pump wasn't only faulty part...

Last edited by lgr122; 11-20-2012 at 06:42 AM. Reason: typo
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  #10  
Old 11-21-2012, 11:57 AM
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rgk330i rgk330i is offline
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It's not a difficult job. As others have said, certainly replace the expansion tank. And while you're at it, replace all the hoses and probably the thermostat. If the water pump is the original, consider replacing that too. This starts to become a bit of work, but would you rather replace it on your schedule, or have it go boom out on the road?

Follow the cooling system bleed procedure carefully to get all the air out of the system.

Some pics from my replacement: http://www.bimmerfest.com/forums/sho...d.php?t=615786

Oh, and if you replace the lower radiator hose, plan on replacing the temperature sensor too, because the shrunken O-ring won't seal properly when you replace it and it'll leak. I got away with it by wrapping a bit of teflon plumber's tape on the sensor beneath the O-ring to bulk it up a little bit, so you might try that.

-Bob
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Last edited by rgk330i; 11-21-2012 at 12:00 PM.
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  #11  
Old 11-21-2012, 02:59 PM
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ahull ahull is online now
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Quote:
Originally Posted by rgk330i View Post
Oh, and if you replace the lower radiator hose, plan on replacing the temperature sensor too, because the shrunken O-ring won't seal properly when you replace it and it'll leak. I got away with it by wrapping a bit of teflon plumber's tape on the sensor beneath the O-ring to bulk it up a little bit, so you might try that.

-Bob
good stuff Bob. Another option - You can actually just replace the o-ring with rubber plumbing o-ring from hardware store:

O-ring only 5/16" ID 9/16" OD and 1/8 thick" failure of the sensor is rare and it's a few bucks for a pack of orings vs $20 for a new sensor. not much $$ either way.
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  #12  
Old 11-29-2012, 03:59 AM
tttomttt tttomttt is offline
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Do a search for filling and bleeding coolant system. Filling and bleeding should be done with engine off, heat temp up full and blower on full i believe. But do a search as I might have forgotton a thing or two.
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  #13  
Old 11-29-2012, 07:08 AM
white_lancer white_lancer is offline
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I guess it helps if the expansion tank low level sensor is plugged in
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  #14  
Old 12-01-2012, 12:35 PM
white_lancer white_lancer is offline
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bled the system again and all working fine now whoop whoop

saved hundreds doing the job myself!

thanks for your help
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  #15  
Old 12-01-2012, 09:47 PM
lgr122 lgr122 is offline
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Originally Posted by white_lancer View Post
bled the system again and all working fine now whoop whoop

saved hundreds doing the job myself!

thanks for your help


Basically you can never be sure if those "professionals" would do it right at once. So few nervous moments about forgetting something, shouldn't hurt too bad.
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  #16  
Old 12-02-2012, 02:37 AM
white_lancer white_lancer is offline
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Whilst i'm in confession mode I also managed to snap off the expansion screw in the hole. I purchased a new one. I heated a screw driver up and inserted this into the broken screw. When it cooled down I simply unscrewed the broken piece. Simples.
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