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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 12-05-2009, 10:47 AM
jps1 jps1 is offline
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Question Lower radiator hose replacement- '04 330i

I started noticing very small spots of antifreeze which gradually turned into large puddles. Coolant light is on and reservoir is empty. I believe the leak is at the lower hose where the hose clamp connects to the radiator.

Is this a hard DIY? The hoses seem pretty cheap. Any suggestions?
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Old 12-05-2009, 10:59 AM
KeithS KeithS is offline
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Changing hoses is very easy. There is thin metal lock ring that you pull back and the hose connection will slide right off (probably be a little stuck after a few years). BUT, the lower radiator hose is normally one of the last hoses to wear out, and BMW hoses last a long time, typically at least 10 years/120K miles (which is exactly what I have on mine). I'm saying this as to look carefully and be sure it is not something else that is leaking such as the temperature sensor which is also in that area on the radiator end or the thermostat on the engine end. .
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Old 12-05-2009, 11:08 AM
jps1 jps1 is offline
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great suggestion. I can't tell if it is the hose itself, but I did see dripping coming from the bottom of the hose/clamp area. My '04 has 91K miles....
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Old 12-05-2009, 11:48 AM
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MicahO MicahO is offline
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Quote:
Originally Posted by jps1 View Post
great suggestion. I can't tell if it is the hose itself, but I did see dripping coming from the bottom of the hose/clamp area. My '04 has 91K miles....
Since it's on the lower radiator hose, the leak may also be coming from the coolant temp sensor that is on that lower connector. Typically that sensor only leaks after the hose has been replaced and the sensor was reinstalled the the new hose without a new Oring, but it could be the source of the leak.

Note - if you do replace that lower radiator hose, you should also replace the Oring on the temp sensor.
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Old 12-05-2009, 12:03 PM
jcourcoul jcourcoul is offline
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Ohky, doky, see here:

http://www.bimmerfest.com/forums/sho...d.php?t=385920
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Old 12-05-2009, 12:33 PM
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MMME30W MMME30W is online now
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Quote:
Originally Posted by MicahO View Post
Since it's on the lower radiator hose, the leak may also be coming from the coolant temp sensor that is on that lower connector. Typically that sensor only leaks after the hose has been replaced and the sensor was reinstalled the the new hose without a new Oring, but it could be the source of the leak.

Note - if you do replace that lower radiator hose, you should also replace the Oring on the temp sensor.
^^^

Good advice.

Standard comment follows: "Consider changing the ENTIRE cooling system -- Upper and lower hoses, thermostat, Water Pump, Tank, Partridge and Pear Tree."

Srsly.

Oh, and if you only have to change the lower hose, is is a major PITA to remove the lower fitting from the rad. I did it on mine at 60K ish. I can only imagine how much the plastic has welded together on your car at 91K miles. Might be an idea to go ahead and order the radiator for when you crack the lower fitting trying to get the hose off.
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Old 12-07-2009, 12:34 PM
jps1 jps1 is offline
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Thanks for the link!
I opted to change out the coolant sensor (I couldn't purchase the o-ring only). No more leaks so far, this may have done the trick and the leak may not be from my hose afterall.
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Old 12-07-2009, 03:46 PM
Holiday27 Holiday27 is offline
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I had the same problem. My leak was from the hose though. My BMW tech friend told me to change the hose and the sensor one time. The lower hose isn't hard to change, just a pain the ass cause it was a little stuck. Leak came at 40K miles on my 04
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Old 12-07-2009, 04:22 PM
mujjuman mujjuman is offline
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Most people recommend that you replace the entire cooling system after a certain time period or mileage.
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