[Jacblack]

Ok I'm at my wits end with trying to get this problem resolved.
I've replaced my radiator and water pump, in addition to new upper and lower radiator hoses and my car still leaks coolant.

The issue isn't consistent so I can't pinpoint it exactly. I just know it leaks from the driver side, well leak is a loose word, it basically dumps coolant onto the ground.

The car doesn't over heat and I haven't noticed any drivability issues either.
I've spent about 3k in repairs and shit still isn't corrected. I dropped my car off to BMW dealer with a coolant leak and left with one as well.

The last thing they said it could be was something related to the trans cooler, but then they wanted me to pay $700 to replace an oil line to fix that problem which didn't make sense to me at all.

Anyone have anything similar? I'm tired of this issue and it's getting expensive having to buy gallons of coolant numerous times a week. Just need this car to last until I can get rid of it in a few months.

[Welcome to NBA Jam]

Get some UV dye. That's the time-tested, best way to identify any leak. You won't get a better view than that. You can also pressure test and listen/look for the leaks.

[Jdub679]

I agree with the previous poster. Also, you can look for water droplet stains. Might help to indicate where the source is.

[weehe126]

As I read your post my first guess was the trans cooler. If you look up your part # on realoem, you probably have a cracked connector at the trans cooler. Not sure what you mean by oil line, but the trans cooler is most likely your problem.

[Jacblack]

Originally Posted by weehe126

As I read your post my first guess was the trans cooler. If you look up your part # on realoem, you probably have a cracked connector at the trans cooler. Not sure what you mean by oil line, but the trans cooler is most likely your problem.

The part that they had listed was 17-22-7-572-713 has the name trans oil cooler inlet tube. That part itself is a almost metal like line, so I was confused as to how this part is making coolant leak. Although I understand the car uses coolant to cool the trans. It's all very confusing to me, I'm so over this car it's my first and last BMW, just feels like the shit is suddenly falling apart lol.

The problem with using the dyes and the pressure testing is that the problem isn't consistent enough. The car passes the pressure test repeatedly, the last time my car was sitting there and no leaks.

The funny thing is that BMW couldn't at first replicate the issue and thought I unplugged something in the car.

The other confusing part is that this problem does happen every single time I drive the car. Like I feel like it should happen every single time move the car, since I got the car back from BMW the longest I was able to go with out filling up the car was a week almost. And mind you I have a 30 mile each way commute.

Does anyone know the process for how the trans cooler works? Like is there a particular temp or rpm it sends the coolant at?

[shadow191]

I don't think there is a thermostat for your transmission cooler, it looks like a direct line. ATF and coolant have similar operating temperatures but coolant heats up faster. So on cold days, it brings up your ATF to operating temperature quicker and it regulates heat when it gets hot. Even if there was a thermostat, a 30 mile commute is more than enough to bring it all up to operating temperature.

Do you see coolant residue on any of the lines or the transmission cooler? When coolant dries, you can usually see some residue. If you've already replaced all those parts, the last thing it could be is the transmission cooler. It's on the driver's side.

[JETmn]

I just had my expansion tank replaced last week due to a small crack. It was acting like yours, but worse. Pressure test found it though, but my leak was also on the pass side.

I agree with others, do a dye test. It is best to drive at low speeds so it doesn't get blown around all over. I would try idling for an extended period of time to see if that could get a small leak going, that would be ideal.

[Jacblack]

Originally Posted by shadow191

I don't think there is a thermostat for your transmission cooler, it looks like a direct line. ATF and coolant have similar operating temperatures but coolant heats up faster. So on cold days, it brings up your ATF to operating temperature quicker and it regulates heat when it gets hot. Even if there was a thermostat, a 30 mile commute is more than enough to bring it all up to operating temperature.

The same thing I said to BMW when they couldn't replicate the issue. They told me they had my car idling for about 6 hrs and no leak. So when I took the car back I drove to work which is about 47 miles from the dealership no leak. I then left work and half way home it dumped out. It's almost as if something is suddenly letting go, I really don't call it a leak but it just seems to all pour out suddenly.

The service manager then tries to tell me that coolant leaks are hard to diagonise so that's why they couldn't find the issue the first time. I honestly think they are tryna make all the money back from the water pump I got fixed under warranty. Mind you they would only warranty my water pump if I replaced my oil filter housing gasket.

I guess I will get the car on a lift and look around again, I'm just tried of dumping money that I could be using as a downpayment for a new car.

[JETmn]

How much boost have you been running? That sounds an awful lot like a head gasket issue. Maybe times they won't leak much at idle, but when you drive them enough pressure leaks in to the coolant system and it pops the radiator cap.

[Jacblack]

I probably haven't even hit more than 5 psi in that car in months. I don't even drive it hard because I'm just sick of it. I thought head gasket but it's not eating the coolant it's leaking it.

No coolant and oil mixing at all, nothing as far as the typical head gasket issues haven't come up. No smoking no eating of oil or anything like that either.

Maybe it is something with related to the trans cooler and maybe BMW was on the right path but just wanted me to replace the wrong part.

[TheBingoBalls]

Where is the leak found or how big is it? Does it start in the front where the bumper/engine is? Centre of the car?

[Jacblack]

It's driver side of the car. The exact location I'm not too sure. But it's not anywhere near the center of the car.

All the times the cars has been the air it hasn't done it. And since the car was leaking coolant from the water pump and rad recently it's hard to follow the residue.

To me it feels like something opens up the coolant leaks out and then boom. I refill it and then it's fine until it happens again, that's why I asked about a certian temp or anything that the trans cooler operates. With my Cobb plugged in I haven't noticed a certian temp and which the leak occurs.

But the real point of this post was to try to get other perspectives or see if someone has had a similar problem.

[JETmn]

As said like 10 times, put some dye in it and track the leak. It isn't rocket science.

[Jacblack]

I understand but like I said before as well this isn't a slow leak over time. It just suddenly does it. So yes I'll grab the dye to pour in, but I'll still be waiting until the car does it again. The dye is most ideal in a situation where you know you have a leak and can have the car in an isolated situation, I.e sitting on a lift waiting to track the leak. I don't have those conditions, I can literally have the car in the air running or off and stand under it and it's bone dry.

The same shit BMW said at first "we can't get the car to leak".

For the past week and a half it hasn't leaked so maybe it will stay this way.

[Jacblack]

Of course just my luck I make that post walk out to get my trash cans and see a huge wet trail that starts from my car.

😡😡😡

[Dhillon92]

Take a jack to where it sits as is and see if u can catch the leak while its fresh (trail and all). There's really no other way to find a leak of this nature.

[TomD335xicoupe]

I had an improperly placed line through vibration ware a pin hole in my AT heat exchange/cooler unit wich is drivers side up front took a bit to find it as it would only leek intermittently but never in large quantities but worth checking closely anyway.

[Jacblack]

I'll try to find time this week to get it back in the air and just go over it inch by inch underneath. I do have a short vid but I could get underneath the car to see where exactly.

[Jacblack]

Update:
Taking it to the shop tomorrow
I've been able to get it to leak twice today, once i arrived to work and shut the car off, a few seconds later boom started gushing out.
Just did the exact same thing again as I just parked in front of my house.

[dauble2k5]

Man, this is intriguing. It sucks it doesn't act up when you've taken it in to have it inspected.

It really sounds like a hose isn't fully clamped down and is getting rattled loose. When you connected the upper/lower radiator hoses, did you have the hose clamps down when you plugged them to the radiator? I guess, did they make a "snap" sound when you connected them?

I'm only asking because I did a cooling system overhaul on my E46 a few years ago, drove around for a couple weeks without any problems, then hit a bump and the low coolant light came on. Pulled into a parking lot to get some distilled water and saw all of the coolant on the ground -- all from the driver's side. Turns out I simply didn't have the lower radiator hose connected properly. I installed them with the clamp UP, rather than down. The second time around, the clamps were down and when connected, they snapped and locked into place.

[Jacblack]

Oh I have no idea how things were installed as I paid "professionals to do it" lol
Nevertheless, my new update is that upon taking it to the shop is that it was the drain plug. I got that replaced. I drove the car hard today and haven't gotten any leaks. So hopefully this was the fix.

[dauble2k5]

Haha, I see.

I hope the plug was the last issue! Good luck, glad it was fixed and keep us posted.