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Old 05-31-2018, 03:52 PM   #1
4thearth
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2004 E46 325i: Anyone ever have BIG heater core leaks?

So i've just about had it with my daily driver 2004 325i Sport 4-dr. Ive had a steady leak for the longest time and for the past few months a little top off of coolant prevents it from overheating. Now, I'm losing so much coolant, so fast that I can't even make a drive around town without an over heat.

The leak is not consistant and just recently can leak so bad its like a consistant little flow, but then stops and will slowly begin to trickle again. The leak is dripping underneath the car, somewhere directly above where the transmission and engine meet. The leak drips on to the trans and then down to the dead center of the car making it look like its coming from the trans/drive shaft area. I've checked all heat system lines that are rubber and all the connections in the engine bay that run to the fire wall and back the the expansion tank and they appear dry, just a little old. All the hoses/water pump for the coolant system was replace by BMW recently ($1400 worth of work and parts). So it has to be either the heating system lines themselves (which like I said I've checked many times) or the heater core itself.

Research online said that if the heater core is leaking that the inside of the cabin would get wet but idk? My interior is dry. Pics I've seen of a dismantled dash and heater seems to show a bottom drain inside the heater core plastic shell that sits behind the ac unit so maybe it drains to right there above the trans?

Has any one ever done a heater core swap? Any input to these issue? I'm at a loss here
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Old 05-31-2018, 05:55 PM   #2
4thearth
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Also to add. Ive gotten my dash apart and gotten a view of the heater core. It looks okayish but I need to get it out but theres no information online on how. I can't figure out how to remove the two pins holding on the hoses on the rad.
Pic here of the clips http://i.imgur.com/wGBsvdr.jpg?1
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Old 06-02-2018, 05:19 AM   #3
ThatE46doe
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You're correct about a clogged heater core will leak inside your car.

Pressurize the system with a small compressor and get to looking for the leak. It will be easy to find.

Based on your information about the location of it dripping down the top of the trans I would check that middle hose on your coolant expansion tank. Follow it towards the back of the fire wall drivers side.
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Old 06-02-2018, 05:22 AM   #4
ThatE46doe
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And if those are the same as the the other coolant lines you put a flat head into the opening then slide the whole metal clip towards you.
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Old 06-03-2018, 03:55 PM   #5
4thearth
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Got it out. Middle of the heater core had a major leak. The black box it sits it does have a drain that goes to right above the transmission. Got it replaced and it seems perfectly fine now
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Old 06-03-2018, 10:11 PM   #6
4thearth
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Now that I have some time I'll detail all the problems and the SOLUTION:

Symptoms:
-Car was leaking LOTS of coolant, but not consistantly
-Brand new expansion tank/radiator and rubber lines
-Intact heating system rubber lines all the way to the fire wall. Including dry connectors and engine rubber lines for heated coolant.
-Leak poured in steady stream at times coming from the exact center of the car
-Coolant was leaking onto transmission and leaking down to the center (rear of trans)

WHAT I DID:
The heater core in my car (once I had it completely out of the car) looked kind of normal. For how much it was leaking and overheating I expected a big blowout. But after filling it with some water and shaking it i could tell that there was a major leak inside the metal fins somewhere that was leaking substantial water. I went to a pull a part a got a similar condition heater core for $16. The black box that the heater core sits in has a drain inside of it that is very effective at pouring the water outside the car. Every post I read said a broken heater core would give you damp carpets or a strong coolant smell but I really didn't have either of these at all.

The clips that attach the metal hoses to the rad are very hard to get out at first and very hard to get back in. I recommend looping some picture wire around the clip so you can use pliers to easily pull back on them. You need to ROCK THE CLIPS LEFT AND RIGHT WHILE PULLING BACK. be careful bc you can damage the radiator with pliers or cut your knuckles on them.

Getting them back on the new heater core is difficult. TAKE YOUR TIME. You cannot reuse O-RINGs here, the old ones have gotten hard and brittle and will not squash back down for you to be able to get the hose down and clip correctly seating. If you don't put it all back exactly it will just continue to leak, but this time... in a new spot! I made this mistake to, going for "it's on there good enough" is not good. I had even worse overheating problems and lost the whole system of coolant in a mile trip.

There is little wiggle room for the metal pipes but i did it without loosening them around the driver foot well.

Other than the few hurdles I faced this was a very straight forward fix and makes me beyond happy i was able to do it myself because stealership quoted $1600!!! They didn't even know what it was. Last time my mother in law took it there they got her for $1400 on this same car for this same coolant leak. They replaced all the front of the car tanks and hoses but didn't solve the real issue.
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Old 06-09-2019, 11:23 AM   #7
bantony
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How to get pins in?

Iím in the middle of this project (plus some front end refresh) and am having a hard time getting the pins back in. They ride up over the back restraints every time, probably because I donít have the lines seated well enough. Any tricks for how you got the lines seated and pins back in?
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Old 07-31-2019, 02:29 AM   #8
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Hi Everyone

I am new to the forum. I too need to change out the heater core on my e46. I purchased. I need to know whether you completely removed your dash or whether you managed to do this job by just removing the radio, climate control and surrounds?

Any idea what self adhesive tape i need to use to stick onto the heater core?
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Old 07-31-2019, 02:30 AM   #9
[email protected]
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Hi

I am new to the forum. I too need to change out the heater core on my e46. I purchased. I need to know whether you completely removed your dash or whether you managed to do this job by just removing the radio, climate control and surrounds?

Any idea what self adhesive tape i need to use to stick onto the heater core?
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