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General E46 Forum
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Old 11-21-2014, 06:41 PM   #1
johnnyv06
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Join Date: Sep 2014
Location: Kansas City, KS
Posts: 17
My Ride: 2005 325xi
Coolant leak (BIG SURPRISE)

So I am a new owner to a 2005 325xi. I've known I have a coolant leak, but due to my not as perfect eyesight, it's harder for me to spot where a leak is coming from, unless I have a general idea of location. I was hoping I could get some advice.

I haven't seen any leak on my driveway until one day I was changing my front brakes. I spotted a puddle around the middle of the car. I am still learning where each component of the coolant system is, but the location of it made me think of a thermostat. I looked at the thermostat since it's right up front, and didn't spot any leaking or residue, so I was left unsure. Based on the location of where I saw the leaking, what components are in that area? I have bought 2 gallons of bmw coolant and 2 gallons of distilled water, mixed, to help buy me time until I find the culprit. I look at the coolant level each weekend. I fill up to the second notch but by the time next weekend hits, the dipstick is back inside the expansion tank, so it's definitely losing a good amount quickly.

I know this is a noobish question, but without the knowledge yet of where everything is, I"m not sure what I'm looking at replacing. Hopefully you guys can help. I appreciate it.
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Old 11-21-2014, 06:51 PM   #2
1BADI5
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Join Date: Oct 2014
Location: Maryland
Posts: 64
My Ride: 00 323i Sportwagen
Be warned......if one of the waterpipes is leaking, no amount of coolant will matter when it finally lets go.

And when things like this happen......the timing is always bad, I'd just it done now.

I'm in the process of completely replacing my coolant system right now
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Old 11-21-2014, 07:11 PM   #3
BMW-North
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Join Date: Feb 2008
Location: SC or ON
Posts: 418
My Ride: 01ci,03i,03xi,04xi
Start looking around the bottom of the expansion tank. That is the black plastic bottle with the rad cap. If you have an automatic you have a couple extra cooling parts. One of these is an output and input for a transmission cooler. This metal boxlike coupler attached beneath the exp tank is a common source for leaks. On my auto xi I had to clamp this on since the o-rings and the single wire lock were not enough to hold both connections. Also check the coolant temp sensor which attaches into the upper side of the lower rad hose which carrier coolant from the bottom passenger side of the rad up to the t-stat.

Looking at the leak on the ground doesn't help much since the coolant leak will drip onto the belly pan (lower plastic engine cover) and run off the low point of that.

Good luck - there's lots of threads on here to help diagnose leaks.

Quote:
Originally Posted by johnnyv06 View Post
So I am a new owner to a 2005 325xi. I've known I have a coolant leak, but due to my not as perfect eyesight, it's harder for me to spot where a leak is coming from, unless I have a general idea of location. I was hoping I could get some advice.

I haven't seen any leak on my driveway until one day I was changing my front brakes. I spotted a puddle around the middle of the car. I am still learning where each component of the coolant system is, but the location of it made me think of a thermostat. I looked at the thermostat since it's right up front, and didn't spot any leaking or residue, so I was left unsure. Based on the location of where I saw the leaking, what components are in that area? I have bought 2 gallons of bmw coolant and 2 gallons of distilled water, mixed, to help buy me time until I find the culprit. I look at the coolant level each weekend. I fill up to the second notch but by the time next weekend hits, the dipstick is back inside the expansion tank, so it's definitely losing a good amount quickly.

I know this is a noobish question, but without the knowledge yet of where everything is, I"m not sure what I'm looking at replacing. Hopefully you guys can help. I appreciate it.
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Old 11-21-2014, 08:29 PM   #4
jfoj
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Join Date: Nov 2009
Location: Fairfax, VA USA
Posts: 12,204
My Ride: '06 330CiC, '03 M5
Another very common problem is a leak the temperature sensor mounted in the lower radiator hose. There is an O-ring that shrinks over time. These tend to leak more when the car is cool. The leak drops on the lower engine cover and often does not make is to the ground.

Closely inspect this area, ANY moisture or staining, the O-ring is leaking.

Simple, no tool required repair. Maybe just a toothpick.

O-ring part number is the last item in my signature.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temps, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose fan switch O-ring - BMW #13621743299
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Old 11-21-2014, 08:39 PM   #5
johnnyv06
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Join Date: Sep 2014
Location: Kansas City, KS
Posts: 17
My Ride: 2005 325xi
I actually just found a video where they talked about the hose fan switch o-ring, so tomorrow I will look at the condition of it and see. I've also known the expansion tank has a high risk of cracking, yet I haven't seen any residue on it. The previous poster is right though. It's hard to tell where it could be coming from because of the belly pan. I'll look at the o-ring and underneath the expansion tank.
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Old 11-21-2014, 10:00 PM   #6
jfoj
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Join Date: Nov 2009
Location: Fairfax, VA USA
Posts: 12,204
My Ride: '06 330CiC, '03 M5
It the temp switch O-ring is over 5 years old, it needs to be replaced.
__________________
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temps, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose fan switch O-ring - BMW #13621743299
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