Help with unidentified coolant leak, [pics included]

Hey guys, I have a coolant leak going on that almost got the best of my car. I was sitting in traffic, then without warning, the low coolant light came on. The engine temp stayed normal though, so I figured maybe the level was just a little low. Sitting at a red light, eyes on the temp needle like a hawk, I saw it start to creep up. I started to get nervous and pulled off to the side of the road when it was safe to, it was in the red zone for probably 30 seconds. I pulled over in a parking lot, opened the hood:

-No smoke anywhere, slight smell of coolant but not strong at all (supports my theory that it all leaked out onto the road)
- Completely EMPTY expansion tank, bone dry, some steam coming from that when the cap was off
- When I put bottled water into the ET, it emptied out onto the pavement at the same rate that I was putting it in up top. It was also pouring rain out, and I had no tools with me, so I couldn't get under there and see what the issue was, but I concluded that the ET exploded.

All of this resulted in this:


The next day, I got under the car with some tools, but couldn't see anything moist or wet, all looked normal, all hoses attached and such. I poured more bottled water into the ET, and this is what I saw:


That fluid is rippling down that black hose device there, not leaking right from that, and that is DIRECTLY beneath the expansion tank.


So today I take out my expansion tank... BIGGEST PITA in the world, this thing would NOT come out. After an hour of wrestling with it, I got it out, but not without breaking the bleed screw valve I know Mango would clap for me for saying I'm going to replace the ET regardless, but now I have no choice. Also, I'm looking at my ET in the sink under a light, and I can't see any noticeable stress fractures or holes or anything.

Anybody have part number or names for the bleeder screw that connects to the bottom of the ET?

If it wasn't my ET that blew up, what could have been the reason coolant just spilled out so quick?

Bump? I accidentally snapped the bleeder valve with the blue plastic screw taking out the ET. As I've said before, I find the ET the only feasible place where coolant could be pouring out at the same rate I poured it in from the top on the driver side right by the radiator. Opinions?

It's hard to tell what I'm looking at (maybe it's the beer??) but seems like there's a big hole. Do you have better pictures?

The usual failure mode for the expansion tank is a hairline crack--one that you won't usually see with the naked eye. But at the rate you're spilling, seems something came loose. any recent work on the system?

Also there's no bleed valve at the bottom of the et.

Tip for next time taking the expansion tank out, get a big heavy duty screwdriver and pry from the bottom of the tank (against the bracket) and you can get the tank out in less than 5 seconds using leverage

If it's pouring out as fast as you pour it in, I'd guess that the hose coming out the middle of the rear-facing side of the tank came loose. If the bottom fitting was compromised it would have been much easier to pop out.

Not that it matters much - when you pop in the new ET you'll find out very quickly whether it was the ET or something else

Hard to see what that is from the picture. It looks like a pressure pocket that exploded right though.

Remember though, plastic expands with heat, so you may not be able to see the crack or hole that easily if there is one in the ET. Either way, that looks to be the culprit.

Probably going to have to do a full flush after adding bottled water, including the heater core removal of coolant.

Originally Posted by 05graysport

Hard to see what that is from the picture. It looks like a pressure pocket that exploded right though.

Remember though, plastic expands with heat, so you may not be able to see the crack or hole that easily if there is one in the ET. Either way, that looks to be the culprit.

Probably going to have to do a full flush after adding bottled water, including the heater core removal of coolant.

That is a little drastic, considering that it leaked right out, and was never circulated.

Originally Posted by MJLavelle

That is a little drastic, considering that it leaked right out, and was never circulated.

To each his own.

1) Ratio is messed up

2) Trace minerals from water

3) Fresh coolant is always better

4) Its cheap.

Not a bad idea in my books

Originally Posted by 05graysport

To each his own.

1) Ratio is messed up

2) Trace minerals from water

3) Fresh coolant is always better

4) Its cheap.

Not a bad idea in my books

uhh okay. i agree with lavelle. but do what you gotta do. you would cringe if you knew how i treated my car and it's still running like new at 250k. here are some hints. hose water and conventional oil.

Originally Posted by Rotha

uhh okay. i agree with lavelle. but do what you gotta do. you would cringe if you knew how i treated my car and it's still running like new at 250k. here are some hints. hose water and conventional oil.

Probably should look into Honda's with those tactics.

Oil change at $2.00/quart every 3000 miles or $6.00/quart every 10,000 miles seems about the same to me, with the benefits of synthetic not breaking down.

I hope your car gives you great service, although I don't plan on driving a car with 250k.

whatever

Originally Posted by Rotha

uhh okay. i agree with lavelle. but do what you gotta do. you would cringe if you knew how i treated my car and it's still running like new at 250k. here are some hints. hose water and conventional oil.

Your engine still running at 250k is cool and all, but it doesn't mean it's healthy--especially on the inside. These powertrains have shown to take a good amount of abuse--something BMWs are known for. However, we've all seen the effects that tap water can have on an engine.

Also your conventionial oil likely doesn't meet BMW spec for high-performance driving as does the recommended Genuine BMW 5W-30 oil or other recommended oils.

So frequent oil changes and normal driving are likely fine with conventional oil.

Originally Posted by 05graysport

To each his own.

1) Ratio is messed up

2) Trace minerals from water

3) Fresh coolant is always better

4) Its cheap.

Not a bad idea in my books

To be clear, I was not saying that he does not need to drain it and refill with new coolant. That is just common sense when doing work on the car.
But telling him he needs to drain the heater core and every drop of coolant because of one bottle of non-distilled water (that leaked right out and was never circulated) is a bit drastic. But I would not think that the ratio is messed up to the point of being noticeable, and the amount of trace minerals introduced is also nearly at the point of being un-measurable.
He should drain the coolant and refill because he is working on the cooling system, and it makes sense to replace coolant that is more than a year old, if you are already working on the system. But worrying about ratios and trace minerals for such a small amount of water being introduced is over the top. It is a car. It is not a surgical environment. Small amounts of contamination are inevitable. If he has new coolant, he could get by without draining any of it, and still be fine. He certainly does not need to worry about flushing the heater core because he basically poured some bottled water through a hole in his expansion tank and never circulated. That is overkill to satisfy your own obsessive compulsive needs, not realistic advice.

Originally Posted by Schlag96

If it's pouring out as fast as you pour it in, I'd guess that the hose coming out the middle of the rear-facing side of the tank came loose. If the bottom fitting was compromised it would have been much easier to pop out.

Not that it matters much - when you pop in the new ET you'll find out very quickly whether it was the ET or something else

Thanks for the input guys! I have a new ET from bavauto arriving this week. I was pondering the idea of trying to repair my mounting bracket with the blue bleeder screw that the ET plugs into at the bottom myself, since that alone is like 60 bucks out there. But I'll probably play it safe and just buy that new unit as well.


To be clearer: The low coolant light came on, car was perfectly fine for about an hour. Then, all of the sudden cars empty and overheated. On the side of the road, water emptied out from directly beneath the expansion tank at the same rate I was pouring it in. But when I took out the ET, everything seemed to be intact. So I guess my next move is just to replace the ET and that bleeder valve I was stupid enough to break and put it all back together as secure as possible and see what happens.

I was thinking it was the bracket that cracked...and I trusted your assessment that ET was fine...but you could always pressure test it with a wet/dry vac blowing or something...just figure out a way to seal up the outlets. You have ET and bracket, so you should be good.

If I find out you've been contaminating the bmw system and using anything but distilled water from an ACEA A5/B8 certified source, you do not want to be in a thread with me again. I'll remember and will never forgive you. Neither will Mango or Gheybe.

Wooh! Nice brand new expansion tank arrived in 2 days from BavAuto! I figure it would be a good idea to thoroughly wash the new tank out with water to get all the cardboard and tiny deposits out of the tank before they infiltrate my cooling system and clog up everything. I picked up some coolant today, so tomorrow I'll attempt to fix and hope and prey that fixes my problems. I miss the car :/ she's been sitting for about a week now.


Updates will be provided!

I don't understand why people keep buying stuff from bavauto. last time i checked, they were worlds more expensive for everything. oh well.

Originally Posted by E46Mango

I don't understand why people keep buying stuff from bavauto. last time i checked, they were worlds more expensive for everything. oh well.

They have a few things that are hard to find but they are even more expensive than ECS Tuning and their site blows.

Originally Posted by WDE46

They have a few things that are hard to find but they are even more expensive than ECS Tuning and their site blows.

like?

And these people aren't buying hard to find things from them. expansion tanks, cooling parts, spark plugs, etc.

I got my expansion tank from bav auto for 45 shipped to my door. It has the same part number as my OEM one I just took out. BavAuto is about an hour from me, so shipping got here in essentially 36 hours. I do agree though, their prices on most other things are an absolute joke.

Originally Posted by E46Mango

like?

And these people aren't buying hard to find things from them. expansion tanks, cooling parts, spark plugs, etc.

Indeed. I don't understand that.

Originally Posted by bostonsc4

I got my expansion tank from bav auto for 45 shipped to my door. It has the same part number as my OEM one I just took out. BavAuto is about an hour from me, so shipping got here in essentially 36 hours. I do agree though, their prices on most other things are an absolute joke.

The part number will always be the same. The manufacturer may not be. $45 was probably a Meyle unit. The "Genuine" part runs about $80. I don't know who the OEM is.


I just discovered the multiquote button. Holy ****.

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